Cardiac Catheterization in Congenital Heart Disease: Pediatric and Adult - Part 6 ppt

With combined aortic stenosis and coarctation, the diameters of the aortic valve annulus and the coarctation with the appropriate adjacent aortic diameters are meas-ured from a left vent

completely The sheath is withdrawn and pressure

applied over the vessel manually As soon as all the

sheaths are out, the drapes over the patient are removed

completely so that the lower abdomen and upper thigh

areas adjacent to the entire inguinal area are visible While

holding pressure over the arterial puncture site with the

fingers of one hand, a pulse distal to the puncture site

(dorsalis pedis or posterior tibial) is palpated with the

fingers of the other hand The amount of pressure applied

over the arterial puncture site is varied or “titrated” so

that just enough pressure is applied to prevent bleeding

(or a subcutaneous hematoma formation) while at the

same time allowing the palpation of a peripheral pulse

continually In larger or heavier patients, it is better

to apply pressure over the arterial site with a firm “roll” of

“4 × 4s”, since the exact site of arterial puncture deep

within thick subcutaneous tissues does not correspond at

all to the site of the skin puncture and subsequent

pres-sure The pressure from the “roll” of bandage covers a

wider area deep within the tissues and is more likely to

control deep bleeding from the artery The same

tech-nique for monitoring the peripheral pulse is used while

pressure is applied with the “roll” of bandage

In addition to the care of the local puncture sites, these

patients are monitored systemically very closely in a

recovery area for at least six hours During this

observa-tion period, they should have a secure intravenous line

and receive a high maintenance infusion of 1/4 normal

saline or Ringer’s lactate The intravenous fluids are

con-tinued for twelve hours A patient following dilation of a

coarctation of the aorta usually has diuresed during the

procedure from both the contrast agents used and from

the increased renal blood flow as a consequence of the

relief of the coarctation Often these patients start out “dry”

from being NPO for a prolonged period of time before the

procedure begins The combination of these factors results

in a very significant volume depletion, which, in turn,

aggravates vagal or other vascular responses caused by

the changes in the distribution of arterial blood flow

Surprisingly, post-dilation patients rarely suffer from

the “post-coarctectomy” syndrome that is seen commonly

following surgery Dilation patients rarely have any

aggravation of their upper extremity blood pressure,

although the systemic pressures may not drop to normal

immediately13 Post-dilation patients essentially never have

abdominal discomfort and usually resume oral intake

within 6–12 hours after dilation There have been reports

of serious post-procedure complications following the

dilation of coarctations, so no matter how smoothly the

procedure went, these patients are observed overnight

Although they may exhibit pain during the actual balloon

inflation in the coarctation site, once the balloon is deflated,

the pain subsides Any persistent or recurrent pain should

be taken seriously and investigated thoroughly

Dilation of coarctation neonates and young infants

Coarctation of the aorta in the neonatal patient presentssome unique features These infants frequently present tothe cardiologist catastrophically ill with heart failure, inacidosis and in shock They frequently have additionaldefects, some of which complicate the catheter manage-ment and some of which actually help the catheter man-agement The identification of any additional defects ismade from the clinical examination and the echocardio-gram The echo cannot consistently provide the detailsabout the coarctation size, anatomy and severity, and fre-quently underestimates the size of the adjacent aortic seg-ments Decisions about therapeutic intervention for the

neonatal coarctation of the aorta should not be made

entirely on the basis of the echo

A vigorous, but brief attempt is made at stabilizinginfants who are less than three to four weeks old with vent-ilation, inotropics, volume support and prostaglandin.Stabilization attempts are continued only as long as the

infant improves If there is going to be any improvement in

the clinical condition, it is noticeable within one to twohours With, or without, the stabilization after that dura-tion of time, the infant is taken to the catheterization lab-oratory If the infant is not responding noticeably to theresuscitative efforts, more time only allows further deteri-oration If the infant is responding, the improvement willcontinue on the way to, and in, the catheterization labor-atory The exact procedure performed depends upon thepresence or absence of associated lesions and, when pres-ent, which associated lesions are present

Besides their general hemodynamic instability, the verysmall femoral arteries with the associated very weak orabsent femoral pulses represent the greatest challenge forballoon dilation of coarctation of the aorta in the verysmall infant In each individual case, the most expeditioustechnique possible is utilized to approach and treat thecoarctation Once the coarctation area has been reachedwith a catheter, the gradient is measured, the selectiveaortogram(s) performed and accurate measurements ofthe coarctation and adjacent vessels are made in order tochoose the proper balloon

When the infant responds to the administration ofprostaglandins with opening of the ductus arteriosus, thestabilization of the infant is usually rapid and very effect-ive The presence of the patent ductus indirectly facili-tates access to the coarctation by improving perfusion

to the lower extremities significantly, and increases theamplitude of the femoral pulses, which facilitates percuta-neous arterial access The presence of a patent ductus,however, compromises the results of balloon dilation of

a neonatal coarctation Without the patent ductus, the

balloon is constrained within the aorta and the “path of

least resistance” is to crush the abnormal ridge of tissue

within the aortic lumen A wide open ductus arteriosus,

on the other hand, allows the dilation balloon to move

away from the coarctation “ridge” into the “ampulla” of

the ductus rather than crushing or compressing the ridge

In addition, when the ductus does constrict during its

nor-mal closure, it probably also constricts some of the

adjac-ent aorta, recreating the coarctation

Most of the newborns and small infants with

coarcta-tion do have at least a potential interatrial communicacoarcta-tion

In all of these infants, venous access is obtained and an

angiographic catheter is introduced into at least the left

ventricle from the venous approach At the same time, in a

small sick infant, no prolonged effort should be made at

advancing this catheter from the left ventricle into the

aorta, as is utilized in coarctation dilation in the older

patient The chambers and vessels are very small and the

tissues “softer” and prone to puncture The catheter in the

left ventricle provides continual systemic pressure

mon-itoring before, during and immediately after the dilation

procedure The pressure in the left ventricle reflects the

severity of the coarctation unless there is associated aortic

stenosis or the infant is in terrible heart failure A left

ven-tricular angiocardiogram is performed which provides

some, and possibly, very good information about the

coarctation and the overall anatomy

Infants who do not respond to prostaglandins and who

have no associated lesions, and those who have associated

aortic stenosis, are the most difficult for coarctation dilation

The echocardiogram should diagnose associated aortic

stenosis and give an estimate of its severity, although

either one of the two lesions can mask the significance of

the other The prograde left ventricular catheter is useful

in these patients for monitoring pressures and for the

administration of fluid and medication, and is possibly

helpful in determining the relative severity of

com-bined lesions

Percutaneous entry into the artery is accomplished with

meticulous attention to detail, a very delicate single wall

vessel puncture technique, and patience (as described in

Chapter 4) The area around the expected arterial

punc-ture site is infiltrated with local anesthesia, being as

care-ful as possible not to puncture the artery with the needle

during the infiltration If the artery is punctured

inadvert-ently, pressure is held over the site for at least 2–4 minutes

before beginning the purposeful puncture of the artery

Special 21-gauge percutaneous needles and extra-floppy

tipped 0.018″ or 0.014″ wires are essential for the

percuta-neous entry into the artery in these patients Once the

artery has been entered with the guide wire, the area

sur-rounding the puncture site is re-infiltrated liberally with

local anesthesia A 3- or 4-French “fine tipped”

sheath/dila-tor is introduced into the artery The preliminary diagnostic

information about the coarctation is obtained with the trograde catheter If the infant is still very unstable, an endand side hole multipurpose catheter is used This type ofcatheter allows pressure measurements and quality aor-togram(s), and at the same time can be used to position theguide wire for the dilation without the necessity of evenone catheter exchange The second catheter previously

re-positioned in the left ventricle helps to confirm the

pres-ence of associated aortic stenosis However, with poor leftventricular function and an associated coarctation of theaorta, even very severe aortic stenosis can be masked

Once the coarctation has been identified as the only

significant lesion, it is measured accurately and the dilation

of the coarctation is carried out as expediently as possibleusing the single-catheter, retrograde technique It ispreferable to stabilize the distal end of the guide wire inone of the subclavian arteries, although an excessivelylong time or effort should not be taken to achieve this loca-tion The balloon for the coarctation dilation is chosen toequal the size of the smallest segment of the aorta adjacent

to the coarctation Once the dilation has been completedand the balloon removed over the wire, the end-holecatheter is re-advanced over the wire and very gently pastthe coarctation to the aorta proximal to the coarctation.The wire is removed and pressures are recorded simulta-neously through the catheter from the ascending aortaand through the side arm of the sheath from the femoralartery A repeat aortogram is recorded, injecting throughthe end-hole catheter proximal to the coarctation site.The catheter should not be withdrawn across the coarc-tation site until all post-dilation studies or any re-dilationhas been accomplished If the dilation was unsatisfactoryand a re-dilation is necessary, the wire is replaced throughthe catheter which is already across and well beyond thelesion in order that no catheter manipulation back acrossthe freshly dilated area is necessary When the catheterhas been withdrawn across the area, it should not bemanipulated back across the area3

Co-existent critical aortic stenosis and coarctation in infants

When there is significant aortic stenosis in associationwith the neonatal coarctation, it is preferable to addressthe aortic stenosis first In the presence of the combinedlesions, perfusion of the coronary and cerebral circula-tions is dependent, at least partially, on the increasedafterload in the ascending aortic pressure provided by thecoarctation Removing this afterload before opening theaortic valve could compromise the coronary and cerebralcirculations even further In addition, if the coarctation isdilated first, all of the manipulations (sometimes extens-ive) required for crossing the aortic valve, and the aorticvalve dilation, will have to be through the freshly dilated

coarctation site with the potential for traumatizing the

already damaged aortic intima in the coarctation site even

further

With combined aortic stenosis and coarctation, the

diameters of the aortic valve annulus and the coarctation

with the appropriate adjacent aortic diameters are

meas-ured from a left ventricular angiocardiogram or an aortic

root injection before an attempt is made to pass a catheter

across the stenotic valve A left ventricular

angiocardio-gram is obtained with injection through a prograde left

ventricular catheter, while the aortic root injection is

obtained with the retrograde multipurpose or

angio-graphic catheter that has been manipulated past the

coarc-tation and around the arch to the aortic root Once the

valve and coarctation measurements are obtained, the

appropriate dilation balloon for the aortic valve dilation is

prepared using the “minimal prep” technique but with

a prolonged attempt at removing all air No attempt is

made to cross the aortic valve until the balloon for the

dila-tion is prepared and “poised” for introducdila-tion These

infants are often so precarious that even a tiny 4-French

catheter crossing the stenotic orifice is enough to cause a

rapid decompensation in their hemodynamics

To cross these valves, a 0.018″ or 0.014″, very floppy

tipped, exchange length, torque-controlled, coronary

artery, guide wire is advanced through a multipurpose or

selective right coronary catheter which is already

posi-tioned in the aortic root The wire is advanced out of the

catheter and multiple, rapidly repeated, short probes are made

toward the aortic valve area with the very soft wire tip

Because even a very soft tipped wire exiting the tip of the

catheter can be very stiff for the first few millimeters out of

the tip, the tip of the catheter is kept a centimeter away

from the valve annulus during the probes with the tip of

the wire The tip of the wire is redirected within the aortic

root by simultaneously rotating the catheter (to change

the anterior to posterior direction) and moving the

catheter to and fro (to change the right to left side angle)

Unless another wire or catheter is already passing

through the valve, the exact location of the orifice really is

not known The more “probes” that are made with the

wire along with multiple changes in the angle of the wire,

the more likely is the chance of the wire passing through

the orifice of the “invisible” valve

If the wire does not cross the valve after trying for

several minutes using the original multipurpose catheter,

the multipurpose catheter is replaced with a preformed,

either right or left coronary catheter and the “probing” at

the valve repeated with similar changes in direction of the

catheter tip The tighter, preformed curves at the tips of

coronary catheters allow a greater ability to change the

angle of approach toward the small valve orifice

Once the wire crosses the valve, it is advanced as far as

possible into the ventricle, hopefully even looping the soft

tip within the left ventricle apex With the wire passed asfar as possible into the ventricle, the catheter is advancedover the wire into the ventricle If the infant’s hemody-

namics do not remain stable with the catheter across the valve, the wire is fixed in the ventricle and the catheter is immediately removed and replaced rapidly over the wire

with the previously prepared balloon dilation catheter.The dilation of the valve is carried out with as rapid aninflation and deflation as possible and while recordingangiographically or on “stored fluoroscopy” After theinflation/deflation, the balloon is immediately with-drawn out of the valve over the wire into at least theascending aorta

If the infant remains stable with the end-hole catheterpassed through the valve, the wire is removed A “pig-tail” is formed on the tip of the long floppy tipped, stiffer,exchange guide wire and a 180° curve is formed on thetransition zone between the long floppy tip and the stiffshaft of the wire This individually formed wire is re-advanced through the catheter into the left ventricle Thepreformed “pig-tail” on the wire keeps the wire from digging into the myocardium as it is manipulated in the

ventricle The 180° curve at the transition area of the wire

directs the tip of the wire back toward the left ventricular

outflow tract and allows the stiff portion of the shaft of the

wire to be positioned further across the valve With thewire maintained in position, the catheter is removed andreplaced with the already prepared balloon catheter Theballoon is positioned across the valve and the inflationperformed while recording the inflation angiographically

or on “stored fluoroscopy” The inflation/deflation is formed as rapidly as possible During the inflation the leftventricular pressure increases and the infant developsbradycardia As soon as the deflation of the balloon iscomplete, the balloon is withdrawn over the wire and out

per-of the aortic annulus The infant’s heart rate should returnand the left ventricular pressure will drop to normal levels.The return of a good heart rate and a good, but lower,left ventricular pressure are immediate indications of thesuccess of the dilation Ideally, there will be a lower leftventricular pressure, but in the presence of the associatedcoarctation, the gradient may be “moved downstream” tothe coarctation site with little lowering of the left ventricu-lar pressure The radiographic recording of the inflation/deflation is reviewed If a “waist” appeared on the balloonand then disappeared during the inflation, some true dilation of the valve orifice is assumed The balloon iswithdrawn back to the area of the coarctation If the dia-meter of this balloon is smaller, or, at least, no more than amillimeter larger, than the measurement of the smallestdiameter of the aorta adjacent to the coarctation, the coarctation site is dilated with the same balloon If the bal-loon is two or more millimeters larger than the adjacentaorta in the area of the coarctation, the balloon is replaced

with an appropriate diameter balloon and the

coarcta-tion dilated

After both the aortic valve and the coarctation have

been dilated the balloon is removed and replaced with a

catheter to re-evaluate the hemodynamics If there is a left

ventricular catheter in place, the “net” results of the

com-bined dilation are determined by measuring the left

vent-ricular and femoral artery pressures simultaneously using

the side arm of the sheath for the femoral artery If the net

left ventricular to femoral artery gradient is low, it is

assumed that both procedures were successful and the

procedure can be concluded A left ventricular

angiocar-diogram through the prograde catheter provides

visual-ization of both the aortic valve and the coarctation area

An end-hole catheter is passed over the wire to the left

ventricle and the retrograde wire removed Pressures are

recorded on withdrawal of the retrograde catheter from

the left ventricle, to the aorta and across the coarctation

site to quantitate the residual gradients at each area

If the net gradient is still significant, the culprit lesion(s)

is/are identified from the pressures and angiograms If

there is no prograde catheter in the left ventricle, the

results of the dilations must still be determined A

Multi-Track™ catheter provides the most “secure” way of

iden-tifying the major residual problem without having to

remove the wire from the left ventricle Pressures are

recorded and angiograms are performed through the

Multi-Track™ catheter anywhere along the course from

the left ventricle to the descending aorta and all without

having to remove the wire, which can be maintained

posi-tioned in the left ventricle A small, stiff wire is placed in

the true catheter lumen of the Multi-Track™ catheter to

stiffen and support the catheter shaft as Multi-Track™ is

being advanced over the exchange wire Once the

Multi-Track™ catheter is in the left ventricle, the wire within the

true lumen is removed Angiograms are performed where

appropriate and pressures are recorded as the

Multi-Track™ is withdrawn over the exchange wire When a

significant area of residual obstruction is identified, the

decision is made whether this should or can be treated

from the pressures, the review of the balloon dilations and

the current angiograms performed through the

Track™ catheter If a lesion is to be re-dilated, the

Multi-Track™ is removed over the wire and the appropriate

balloon dilation catheter reintroduced to the culprit lesion

If a Multi-Track™ catheter is not available or cannot be

used with the particular system, then an end-hole,

multi-purpose catheter is advanced over the wire to the left

ventricle and the exchange wire removed Pressures

are recorded and sequential angiograms are obtained

through this catheter as it is withdrawn from the left

vent-ricle to the ascending aorta and from the ascending aorta

to the descending aorta This, of course, removes the

pre-viously secure wire access back into the ventricle! If the

significant or predominant gradient is at the aortic valve,the catheter withdrawal is stopped in the aortic root and adecision is made as to whether further catheter therapy ispossible If the aortic valve is to be re-dilated, the softfloppy tipped wire is reintroduced through the catheterand manipulated across the aortic valve into the left ven-tricle The dilation procedure is repeated with a moreappropriate diameter balloon

If there is a significant net left ventricle to femoral arterygradient, but little or no gradient at the aortic valve, thecoarctation is still the culprit The previous coarcta-tion dilation is reviewed If a larger balloon can be used,the wire is reinserted into the catheter and positioned

in the aortic root before the catheter is withdrawn across the coarctation The end-hole catheter is removed over thewire, the appropriate diameter balloon is passed over the wire and the coarctation re-dilated Reassessment ofthe result depends upon which catheters are available,

as described above

Whenever an infant is found to have coarctation of theaorta with aortic stenosis, associated mitral stenosis ofsome type and degree should be suspected The Shone’scomplex of multiple left heart obstructive lesions includesvarious types of mitral valve stenosis along with thecoarctation and aortic stenosis, and frequently results

in an even sicker infant Any one, or all, of the levels ofobstructive lesions can be severe and require intervention,however usually the coarctation and aortic lesions are themost pressing and are the only ones that can be addressedreasonably in the newborn period Congenital mitralstenosis can be treated by balloon dilation in the slightlyolder child, and is addressed separately in Chapter 20.The most favorable associated lesions in an infant withcoarctation that need dilation are a ventricular septaldefect (VSD) and transposition of the great arteries AVSD provides access to the aorta from the right heart and

in turn from the venous access Although access to the

coarctation through the VSD is anticipated, these infantsshould have an indwelling arterial line for systemic pres-sure monitoring In these patients, a curved tipped, end-hole or multipurpose catheter introduced through a shortsheath from a percutaneous venous introduction is usedfor the “right heart” procedure In infants, when manipu-lating a venous catheter from the right ventricle towardthe outflow tract, as the catheter is torqued clockwise,

it frequently and, even preferentially, passes dorsallythrough the ventricular defect and, from there, into theascending aorta Otherwise, with purposeful manipula-tion of the catheter dorsally and cephalad from the rightventricle, entering the aorta almost always is accom-plished in infants with a significant VSD From there,approaching the coarctation around the arch is a straight-forward procedure with a wire and curved tip catheter

A selective aortogram is performed and the lesion and

adjacent vessels measured accurately The coarctation

is crossed with a prograde end-hole catheter and the

catheter is exchanged for the exchange length, stiff, guide

wire The balloon is introduced from the vein and

advanced through the right ventricle, through the VSD

and to the coarctation The dilation is accomplished all

prograde from the venous entry site without the need

for even a 3-French sheath in a femoral artery The

post-procedure measurements are carried out with an end-hole

catheter replacing the balloon catheter in the aorta before

the “prograde” guide wire is removed

The same ability to perform a dilation of a coarctation

from a venous access holds true for infants with

coarcta-tion of the aorta in associacoarcta-tion with transposicoarcta-tion of the

great arteries (with or without a ventricular septal defect

or aortic or pulmonary override) This is a particularly

common association in patients with the so-called Taussig–

Bing complex of transposition of the great arteries,

ven-tricular septal defect and pulmonary artery override A

standard end-hole or a balloon “wedge” catheter passes

easily from the right ventricle and out into the aorta With

minimal manipulation the catheter is maneuvered into

the descending aorta to the coarctation The diagnosis and

dilation are performed similarly to that in the infant with

an associated VSD

Intravascular stents in coarctation of the aorta

The use of intravascular stents for the treatment of

coarc-tation of the aorta has become the primary approach for

coarctation in the larger adolescent and adult The use and

advantages of intravascular stents in both native and

re/residual coarctation are covered in detail in Chapter

25 Their use in conjunction with dilation of coarctation of

the aorta has changed the approach to these lesions

dra-matically Intravascular stents not only support the

ves-sels at the maximal dilated diameter of the balloon, but

also, in doing so, eliminate the need for any over-dilation

of the vessel

However, the basic rules for the implant of

intravascu-lar stents in pediatric and congenital lesions apply even

more stringently to their use in coarctations In particular,

no stent should be implanted in the aorta if it cannot be

dilated up to the ultimate adult diameter of the aorta in that

particular patient This “rule” so far has precluded the

rea-sonable and/or sensible use of stents in coarctation of the

aorta in infants and small children The implant of a stent

that cannot be dilated to the diameter of the adult aorta,

creates a new, very fixed diameter coarctation as the

patient grows A coarctation with a stent in place, which is

too small for the aorta and which cannot be dilated

fur-ther, must be managed surgically There is a much higher

risk for surgery on a coarctation with a stent in place than

for the surgical repair of native coarctation, even in an

infant The narrow segment of aorta that contains thestent, at the very least, must be “filleted” open and thenpatched, if not totally resected or bypassed with a pros-thetic graft At the same time, this same patient whorequires such extensive surgery on the aorta, no longerhas the extensive collaterals to protect the spinal cord andthe lower half of his body Hopefully, the further develop-ment of “open ring” stents or some type of resorbablestent, will eventually make it possible to use stents in theinitial treatment of coarctation in infants and children

In the interim, balloon dilation of coarctation is veryeffective in infants and children Even if the obstruction ofthe coarctation is not eliminated totally with an initialdilation, or even with several balloon dilations, if the aorta

is not over-dilated and torn or ruptured, a successful loon dilation with a stent implant can be accomplishedwhen the patient reaches adolescence or adulthood Forthe infant and child, a “conservative” dilation of bothnative and re/residual coarctation should be the primaryapproach to these lesions

bal-Complications specific to coarctation dilation

The majority of the early dilations reported in theValvuloplasty and Angioplasty of Congenital Anomalies(VACA) registry were for re-coarctation of the aorta and,

as a consequence, the majority of the acute complicationswere in these re-coarctation dilations In the VACA series

of re-coarctation dilations there were five deaths (twovagal, one aortic rupture, one CNS death and one deathdue to shock)1

A better understanding of the effect of the post-dilationvasodilation and the exaggerated physiologic vasovagalresponse to the pressure drop associated with dilationshas helped to eliminate the extreme vasovagal response

to the procedure The patients are maintained on a highmaintenance volume of intravenous fluids during thedilation and this fluid infusion is maintained for six totwelve hours after the dilation The intravenous access

is left in place until after the patient is ambulated Withthese precautions, the vasovagal type reactions have been eliminated

Significant central nervous system (CNS) injuries and atleast one death attributed to CNS injury have beenreported following dilation of coarctation of the aorta The

exact etiology of all of the CNS injuries has never been

determined unequivocally Fortunately, with more tion to the position of the distal end of the guide wire forsupport of the dilation balloon and extremely stringentprecautions concerning emboli from the materials and/orthe procedure, the central nervous system complica-tions essentially have been eliminated It is critical that the

atten-distal end of the support wire is not positioned in a carotid

or vertebral artery or possibly even in the ascending aorta

Catheters passed over wires are maintained on a

contin-ual flush in order to eliminate any accumulation of blood

and clot around the wire within the catheter or at the

wire–catheter interface Flushing over the wire is

accom-plished by introducing the wire through a wire

back-bleed valve with a flush side port, which is attached to the

hub of the catheter The side port of the wire back-bleed

valve is maintained on continual flush from the

pres-sure/flush system In spite of the theoretical potential for

an aortic tear, patients undergoing coarctation dilation are

heparinized fully with the hope of eliminating clot

forma-tion on the wires or catheters

Although possible, acute, through and through tears in

the aortic wall from the dilation of coarctations have been

exceedingly rare One report early in the history of

dila-tion of coarctadila-tion of the aorta was in a patient with

re-coarctation of the aorta who had remarkably little or

no reaction or scar formation from the prior surgery and

apparently little or no reaction to the acute local injury

The patient had a through and through tear in the aortic

wall and eventually succumbed to the lesion Possibly,

aortic tears cannot be avoided unequivocally, however it

appears likely that aortic tears can be prevented by less

aggressive initial dilation of aortic coarctations and not

over-dilating any segment of the aorta adjacent to the area

of the coarctation by measuring that area of the aorta and

using that measured diameter to determine the diameter

of the balloon for the dilation Dilation of a typical “native”

coarctation presumably tears a “membrane” that lies

across the lumen of the aorta and does not extend the tear

significantly into the wall of the aorta Dilation of an

equally tight “re or residual” coarctation probably involves

dilation of the actual wall of the aorta which has

con-stricted down in the area of the previous therapy and, as a

consequence, these should be dilated more conservatively

Most patients exhibit pain acutely during the process of

inflating a balloon in the aorta, however the pain subsides

when the balloon is deflated If a patient has persistent pain

after acute dilation of the coarctation, the area of the

coarc-tation should be investigated carefully with selective

aortography or intravascular ultrasound in the area of the

dilation Even without identifying a tear, the patient

should be observed in the catheterization laboratory until

the pain subsides or for one or more hours if the pain

persists If a through and through tear with progressive

extravasation is detected, the balloon is reinflated at a low

pressure in the area of the tear The inflation is just enough

to “tamponade” the vessel and allow the patient to be

taken to the operating room for a repair Such a surgical

aortic repair certainly will require relatively prolonged

cross clamping of the aorta and in turn, may require

femoral vein to femoral artery bypass

There has been one report of paraplegia following a balloon dilation of a re/residual coarctation of the aorta in

a small infant with associated complex congenital heartdisease14 The prior surgery on the aorta had involved anuncomplicated end-to-end anastomosis There was no pro-longed ischemia, no evidence of aortic tear nor any evid-ence for embolic phenomena to explain the paraplegia

In the early reported series of coarctation dilation, therewas an 8.5% incidence of significant enough injury to thearterial introductory site to require intervention or havepermanent sequelae at the entrance site into the vessel Inthose early years of balloon dilation, the balloon dilationcatheters were very large and the balloons themselveswere large and grotesque by today’s standards All of theballoons greater than 6 mm in diameter were on 9-Frenchcatheter shafts, the balloons were relatively thick walledand they did not fold well around the catheter so that theballoon “mass” had a very large profile In order to beintroduced through a sheath these balloons required an11- or 12-French sheath! As a consequence to “reduce thesize” of the entry hole into the vessel most of these earlyballoons were introduced into the vessels directly over awire without a sheath in the vessel This in fact probablydid not reduce the diameter of the “hole” in the vessel

wall and certainly contributed to significantly more local

trauma to the vessel walls Considering the ballooncatheters used at that time, the incidence of arterial injuryactually was remarkably low!

Many refinements in the balloons with marked tion in the size of the catheter shafts and decrease in theballoon profiles have not only allowed a smaller “hole” for introduction into the vessel, but have also allowed dilation balloons routinely to be introduced throughindwelling sheaths With the combination of smaller balloon profiles, routine use of indwelling sheaths, verymeticulous care of the introductory sites into the arteries,liberal, repeated use of local anesthesia, heparinization(perhaps?), and personal attention to the site duringhemostasis after the balloon/sheath is removed, local vessel injury is now very rare

reduc-When an acute arterial injury does occur, it is treatedaggressively at the time of the catheterization With anabsent pulse, the patient is continued on heparin therapyfor one or two hours or until the pulse returns If there is

no return of a pulse within 1–2 hours the patient is eitherbegun on thrombolytic therapy with continued heparin

or is taken back to the catheterization laboratory for amechanical recanalization of the vessel, as described inChapter 34 on purposeful perforations

With only a 20-year history of balloon dilation of tion of the aorta, any long-term adverse sequelae from the procedure are as yet unknown The “longer-term”adverse sequelae that have occurred so far, seem to occurmore with the dilation of “native” coarctation of the aorta

coarcta-where the aorta is not “protected” by a surrounding area

of scar tissue, as is found around the re-coarctations The

most bothersome finding after coarctation dilation is the

creation of an “aneurysm” at the site of the coarctation

dilation The incidence of these aneurysms has varied

markedly in different series, but in general they are rare

The “aneurysms” are usually a small out-pouching in

the aortic wall in the area of the balloon dilation This

out-pouching is usually apparent immediately after the

dilation In most cases the out-pouching does not enlarge

and in fact seems to remodel into the aortic wall along with

the overall remodeling of the aorta The out-pouching of

the aorta is considered an aneurysm when the area

“remodels” into a persistent, discrete out-pouching There

are no reported long-term adverse consequences of the

aneurysms, however, in at least one series, several of

the patients with an aneurysm did undergo surgery for

it The indication for the surgery was not because of

any clinical problem due to the aneurysm, but because of

the fear of what might happen to the aneurysm over time

The pathology of those aneurysms that were operated

upon showed tears through the intima and media of the

vessel wall Some aneurysms have been followed for

as long as 18 years with no increase in their size and

no sequelae

Aneurysms of the aorta following surgical repair are not

uncommon These aneurysms are more frequent when

there is a persistent narrowing of the aorta proximal to the

coarctation repair site or when the surgical repair was

carried out with a patch angioplasty These post-surgical

aneurysms are large saccular dilations of the entire area

of the coarctation/aorta distal to the more proximal

“obstruction” Most of these aneurysms continue to

grow with time and most have been referred for surgical

revision

The total incidence of aneurysms following

coarcta-tion dilacoarcta-tion initially was small and actually seems to be

decreasing and, possibly, not occurring at all in more

recent series In the earlier days of coarctation dilation, the

measurements of the coarctation and the adjacent vessels

were less accurate, and less attention was paid to the

narrow adjacent structures Often, marked over-dilation

of these areas was carried out with balloons significantly

larger in diameter than the adjacent vessel, either because

of the inaccuracies in measurement or purposefully in an

attempt to achieve a more lasting result Perhaps the more

conservative dilations done with the knowledge that the

aorta can be dilated further later or can be held open

with an intravascular stent without the need for any

over-dilation will totally eliminate the aneurysms associated

with coarctation dilations When a discrete aneurysm

does occur, it should be followed closely, probably at

least every one or two years with repeated CT, MRI, or

angiographic imaging

A discrete aneurysm can be excluded by a stent graft(large covered stent) or covered with a standard intra-vascular stent to support the aortic wall in the area andthen to have coils packed into the aneurysm behind theintravascular stent

Conclusion

Balloon dilation is an accepted standard treatment forboth native and re/residual coarctation of the aorta inpatients of all ages in many major cardiovascular centersdealing with congenital heart disease The safety of theacute procedure now appears to be very good, perhapsbecause of a better understanding of the lesions and amore conservative approach to the dilation procedure

A patient who undergoes a conservative dilation of tation of the aorta and who has a less than optimal result,but at the same time has no complications, can always havethe dilation of the coarctation repeated with, or without,the implant of an intravascular stent to “complete” theprocedure

coarc-The success of dilation of coarctation of the aorta overthe years and the reduction in the complications and the difficulties with repeat surgery on patients withre/residual coarctation have made dilation of native andre/residual coarctation the procedure of choice in mostcenters Most centers stipulate that all patients who havedilation of any type of coarctation of the aorta should befollowed indefinitely In patients who are, or are at leastnear to, full-grown many centers now regularly performprimary intravascular stent implants along with dilation

of coarctation of the aorta The use of stents in coarctation

of the aorta is covered in detail in Chapter 25

References

1 Hellenbrand WE et al Balloon angioplasty for aortic

re-coarctation: Results of the Valvuloplasty and Angioplasty

of Congenital Anomalies Registry Am J Cardiol 1990; 65:

793–797.

2 Tynan M et al Balloon angioplasty for the treatment of native

coarctation: Results of the Valvuloplasty and Angioplasty

of Congenital Anomalies Registry Am J Cardiol 1990; 65:

790–792.

3 Finley JP et al Balloon catheter dilatation of coarctation of the

aorta in young infants Br Heart J 1983; 50: 411–415.

4 Lock JE et al Balloon dilation angioplasty of aortic

coarcta-tions in infants and children Circulation 1983; 68(1): 109–116.

5 Kappetein AP et al More than thirty-five years of coarctation repair An unexpected high relapse rate J Thorac Cardiovasc

7 Kalita J et al Evoked potential changes in ischaemic

myelo-pathy Electromyogr Clin Neurophysiol 2003; 43(4): 211–215.

8 John CN et al Report of four cases of aneurysm complicating

patch aortoplasty for repair of coarctation of the aorta Aust

NZ J Surg 1989; 59(9): 748–750.

9 Fletcher SE et al Balloon angioplasty of native coarctation of

the aorta: midterm follow-up and prognostic factors J Am

Coll Cardiol 1995; 25(3): 730–734.

10 Anjos R et al Determinants of hemodynamic results of

bal-loon dilation of aortic recoarctation Am J Cardiol 1992; 69(6):

665–671.

11 Bonhoeffer P et al The multi-track angiography catheter: a

new tool for complex catheterisation in congenital heart

13 Choy M et al Paradoxical hypertension after repair of

coarc-tation of the aorta in children: balloon angioplasty versus

surgical repair Circulation 1987; 75(6): 1186–1191.

14 Ussia GP, Marasini M, and Pongiglione G Paraplegia ing percutaneous balloon angioplasty of aortic coarctation: a

follow-case report Catheter Cardiovasc Interv 2001; 54(4): 510–513.

In most major pediatric centers balloon dilation of the

aor-tic valve in the cardiac catheterization laboratory is the

accepted standard for the primary treatment of aortic

valve stenosis Balloon dilation of aortic valve stenosis to

treat valvar aortic stenosis was first published in 19841

Balloon dilation of the aortic valve provides palliation that

is comparable to the palliation for similar aortic valve

stenosis achieved by a surgical aortic valvotomy, but

without the risks and morbidity of surgery2,3 Significant

improvements in the dilation balloons, guide wires and

techniques over the past 15 years have improved the

suc-cess rate and decreased, but not eliminated, the morbidity

and mortality of the aortic dilation procedure for infants,

children and adolescents The indications for dilation of

the aortic valve are similar to the indications for surgical

aortic valvotomy and, as with the indications for surgery,

the indications for balloon dilation vary with the age of

the patient

In the newborn the diagnosis of aortic valve stenosis

comprises a very heterogeneous spectrum of anatomy,

including everything from a nearly atretic aortic valve

with a small aortic annulus and/or an associated very

small, hypoplastic left ventricle, to an equally stenotic

valve, but with a large, dilated poorly functioning left

ventricle The exact anatomy and the resultant left

ventric-ular function determine the indications for balloon

dila-tion in this group The echocardiographic demonstradila-tion

of aortic valve stenosis with associated poor left

ventricu-lar function or low cardiac output, particuventricu-larly with an

otherwise “normal” sized left ventricle, is a major

indi-cation for intervention in a newborn regardless of the

measured gradient by either echo or catheterization4

After the clinical evaluation along with a quality

echocar-diogram, the definitive diagnosis of valvular aortic

steno-sis is established by the hemodynamics obtained in the

catheterization laboratory In the older infant and young

child with clinical findings of aortic valve stenosis, theindication for valvotomy is determined from the peak topeak hemodynamic gradient measured across the valve inthe catheterization laboratory In the absence of any signs

of “poor ventricular function”, aortic valve dilation is formed arbitrarily in very young children for a peak topeak gradient greater than 65 mmHg across the valve.Very young children do not participate in organized,severely strenuous, or sustained physical activities and donot create much additional gradient with their level of activ-ity In adolescent and adult patients, who are more likely

per-to participate in severely strenuous or sustained physicalactivity, symptoms referable to the heart or a measuredpeak to peak gradient across the valve of over 50 mmHg isthe arbitrary indication for valve dilation These criteria

were established for a surgical aortic valvotomy on the

basis of “natural history” studies, and probably are tooconservative for balloon dilation of the aortic valve

General anesthesia with intubation and controlled lation is used in newborns, in critically ill patients withaortic stenosis, and in any patient in whom the carotidartery approach is being used The same general proced-ure is used for the “diagnostic” cardiac catheterization of

venti-the patient who is not critically ill but who is undergoing

aortic dilation, as is used for the catheterization of anyother patient The catheterization is performed underdeep sedation and local xylocaine anesthesia with supple-mental sedation given intravenously periodically through-out the procedure A secure peripheral intravenous and

an arterial line are established and an indwelling “Foley”catheter placed in the bladder in all patients past infancywho are undergoing a balloon dilation of the aortic valve.There are several different approaches and techniquesutilized to accomplish balloon dilation of a stenotic aorticvalve The specific technique used depends upon the

19

particular circumstances of each individual patient and

also on the individual preferences of the operator and/or

the catheterization laboratory The aortic valve can be

approached retrograde from the femoral, brachial,

um-bilical, or carotid arteries The aortic valve can also be

approached prograde from the right heart after passing

into the left heart through either a patent foramen ovale

or by crossing through the intact atrial septum with a

transseptal puncture The atrial transseptal approach to

the left atrium is the preferred technique to acquire the left

heart hemodynamics and angiography when the atrial

septum is intact, while the retrograde approach through

the femoral arteries is the most commonly used approach

for the actual balloon dilation of the aortic valve A

double-balloon dilation of the valve using a retrograde approach

from both femoral arteries is preferred for most aortic

valve dilations5

Technique

For the combined prograde and retrograde approach to

the aortic valve dilation procedure, a short venous sheath

is introduced into one femoral vein and two very small

indwelling arterial cannulae are introduced into both the

right and left femoral arteries The right heart

catheteriza-tion is performed using an angiographic “marker” catheter

introduced through the short venous sheath When a

transseptal procedure is to be performed and there are

any concerns about or a peculiarity of any part of the

anatomy of the left heart, an angiocardiogram is

per-formed with injection into the pulmonary artery before

the transseptal puncture The recirculation of the contrast

through the left atrium and left ventricle clearly

demon-strates the exact positions and any peculiarities of the left

heart anatomy

The left heart hemodynamics are obtained by means of

a prograde left heart catheterization either through a

pre-existing interatrial communication or through a

trans-septal atrial puncture Using the prograde approach to the

left heart, all of the hemodynamics, as well as quality,

select-ive left ventricular or aortic angiograms, are obtained

before any “time” is incurred in the arteries with the larger

indwelling arterial sheaths When the necessary right

heart information has been obtained, the prograde venous

catheter is advanced into the left atrium and from there

into the left ventricle Pressures are recorded from the left

ventricle and the femoral arteries, and the left ventricular

angiography is obtained to determine the severity and

type of the aortic stenosis

In the absence of a pre-existing atrial communication,

the right heart catheter and short venous sheath are

replaced with a transseptal set of the largest French size

the patient can accommodate comfortably and safely The

long sheath of the transseptal set should have an attachedback-bleed valve with a side arm/flush port A trans-septal left atrial puncture is performed using the longsheath/dilator transseptal set as described in detail inChapter 8 Once the long sheath is positioned in the leftatrium and the sheath and its back-bleed valve apparatusare cleared meticulously of all air and clots, the side port

of the sheath is attached to the pressure/flush system Atthis time in the procedure, the patient is given 100 mg/kg

of heparin through the long sheath An angiographic

catheter one French size smaller than the sheath is advanced

through the sheath and manipulated from the left atriuminto the left ventricle Simultaneous pressures are re-corded from the left atrium, left ventricle and a femoralartery With the knowledge that the femoral artery pres-sure can be as much as 20 millimeters higher than the aor-tic root pressure as a result of the elastic recoil of thesystemic vasculature, this measured difference in pres-sures between the left ventricle and femoral artery gives

an estimate, but does not give an accurate measurement of

the true transvalvular aortic gradient

Following the transseptal puncture and when the initialpressures have been recorded, a selective biplane angio-cardiogram is performed with an injection into the leftventricle The angiocardiogram defines the preciseanatomy of the aortic root and the aortic valve stenosis,and demonstrates any associated left ventricular outflowtrack abnormalities At least one view of the angiocardio-grams should be as close to perpendicular to the valveannulus as possible The lateral (LAT) X-ray tube is placed

in a 60° left anterior oblique position with between 30° and60° cranial angulation The amount of cranial angulation

is determined by how horizontally the heart is situated

in the chestathe more horizontally the heart lies in the

thorax, the greater the cranial angulation The posterior–anterior (PA) X-ray tube is placed in a 30°, right anterioroblique position with 30+° of caudal angulation The PA

tube should be almost perpendicular to the LAT tube inboth planes If the valve is not cut precisely on edge withthe initial picture, the X-ray tubes are rotated appropri-ately and the angiocardiogram repeated Very accurate

angiographic measurements are made of the diameter of the

valve annulus at the base of the aortic sinuses where thevalve leaflets attach or “hinge” in the annulus The meas-urements are obtained from a systolic frame where theleaflets are open and the annulus is at its largest diameterduring the cardiac cycle The measurements must be cali-brated against a valid reference measurement system.Depending upon the measurement system in the particu-

lar laboratory, an exact determination of the actual

dia-meter of the valve annulus is made or calculated utilizing an accurate reference system for calibration of the measure-

ments As discussed earlier in Chapter 11, the use of thediameter of a catheter as the reference measurement is not

satisfactory, and, in fact, creates dangerous errors when

measuring large structures such as valves and large

ves-sels A calibrated “marker” catheter, which is positioned

exactly in the angiographic field, is frequently used and

represents a very accurate reference system for

calibra-tion The measuring “bands” on the calibrated catheter are

placed in the plane of the valve and aligned exactly

per-pendicular to the left ventricular outflow tract during the

injection for the valve measurement The catheter tip can

be either in the aortic root, left ventricular outflow tract, or

even in the left ventricular apex Often the catheter moves

during a pressure injection and as a consequence of this

movement, the “marker bands” on the catheter will

usu-ally align precisely on edge for the calibration

measure-ments during at least several frames of the angiogram If

not, the catheter is repositioned to align the marks on edge

before either the X-ray tubes, the table or the patient are

moved and a very brief “cine” of the exactly aligned marks

is recorded with the new catheter position

As an alternative, a “marker” catheter can be positioned

in the superior vena cava immediately adjacent to the

aor-tic root, and in this position it serves as a precise

calibra-tion reference in the same reference plane as the aortic

valve The separate marker catheter in the superior vena

cava, simultaneously with the use of the transseptal

tech-nique, necessitates the use of an additional venous line for

the marker catheter Similarly, a marker catheter can be

introduced into the esophagus with the “marks”

posi-tioned in a location immediately behind the cardiac

silhouette and adjacent to the aortic valve and, in that

position, used as an accurate reference system for

calibra-tion Some X-ray systems have calibration marks

embed-ded in the image intensifier screen The changes in the

distance of these marks to the “isocenter” of the image are

computed constantly and accurately by the sophisticated

computer system, which allows the use of these marks for

a very accurate calibration reference regardless of the

position and distance of the intensifier When such a

built-in calibration reference system is available and it is

verified against a grid or marker catheter reference

sys-tem, it is the most convenient and accurate calibration

system available

An external grid or a metal “sphere” of a known, precise

diameter placed in the exact plane of the valve as described in

Chapter 11 (Angiography) can also be used as the accurate

calibration reference The external grid or sphere is a very

accurate but very inconvenient reference system

Once the measurements of the valve annulus have been

completed, the X-ray tubes are placed in the positions that

will be utilized during the valve dilation Biplane records

of the best images of the valve from both planes of the

biplane angiograms in this same angulation are stored in a

“freeze frame” to be used as a “road map” during the

valve dilation If there is not a good “freeze frame” replay

capability available, it is useful to place tiny lead markers

on the chest wall exactly over the area of the aortic valveannulus on the fluoroscopic image Fluoroscopy is used toalign the “lead” marks on the chest wall according to thelocation of the valve as seen on the previous angiocardio-grams in the same X-ray views

The long transseptal sheath is advanced over thecatheter and into the left ventricle An “active deflectorwire” is introduced through a wire back-bleed/flushvalve into the original angiographic catheter and thecatheter is deflected 180° toward the aortic valve Whileholding the curve on the deflector wire and fixing the wire

in place, the catheter is advanced off the wire, through the

left ventricular outflow tract, and into the aorta This isaccomplished readily when an end-hole or angiographic

woven dacron catheter is used These catheters become

very soft and flexible after only a few minutes in the lation at body temperature, and as a consequence are relat-ively atraumatic and easily deflected

circu-An alternative technique for advancing a catheter fromthe left ventricle into the aorta is to use a floating ballooncatheter through the long sheath, which is positioned inthe left ventricle The original angiographic catheter isremoved from the long sheath while the long sheath ismaintained in position in the left ventricle The longsheath is cleared thoroughly of all air and/or clot The dis-tal end of a floating balloon angiographic catheter, which

is at least one French size smaller than the sheath, is “pulled”

or softened in heat and then formed into at least a 180°curve at the distal end The balloon angiographic catheter

is introduced into the long sheath and advanced throughthe sheath and into the left ventricle During the introduc-tion and the entire time the balloon catheter is beingadvanced within the sheath, both the sheath and the

catheter are maintained on a constant flush Once the

bal-loon tip is beyond the sheath in the left ventricle, the balloon catheter and sheath are switched to pressure monitoring, the balloon is inflated with CO2, and usually,using minimal manipulations, the balloon catheter floatsout of the left ventricle, across the stenotic valve, and intothe ascending aorta In the presence of a very tight steno-sis, the balloon must often be deflated partially, or evencompletely, just beneath the valve in order for the catheter

to pass through the stenotic orifice Occasionally the

“active deflector wire” is used along with the floating loon catheter in order to redirect the catheter tip 180° awayfrom the apex and toward the valve

bal-Once a catheter has passed into the aorta, simultaneousleft ventricular, aortic root, and femoral artery pressuresare recorded, with the left ventricle pressure recordedfrom the side arm of the sheath, the ascending aortic pres-sure from the catheter, and the femoral pressure from the femoral line These pressures provide the true peak-

to-peak hemodynamic gradient across the valve and a

comparison with the original left ventricle to femoral

artery pressures In order to obtain even better

visualiza-tion of the valve leaflets, an aortic root aortogram is

recorded through this prograde catheter The soft catheter

alone passing through the valve does not produce

significant artifactual aortic regurgitation When the

aor-tic root angiogram has been recorded, the prograde

catheter is advanced further out of the ventricle and the

tip advanced around the arch and into the descending

aorta (at least beyond the brachiocephalic trunk!) When

the hemodynamics have been recorded, both the catheter

and the transseptal sheath are placed on a slow

continu-ous flush The transseptal sheath remains in the left

vent-ricle and the catheter in the descending aorta before, during

and after the dilation procedure This allows

simultane-ous aortic and left ventricular pressure monitoring and

recording during and immediately after the dilation

proced-ure In addition, both the catheter in the aorta and the

transseptal sheath in the left ventricle serve as routes

for rapid infusions of intracardiac fluids or medications

Of equal importance, the shaft of the catheter that is

pass-ing through the stenotic orifice of the aortic valve serves

as a visible and definitive “guide” for the subsequent

introduction of the retrograde wires/catheters across the

valve

With the prograde catheters in place and the

measure-ments of the valve completed, the balloons for the dilation

are chosen and prepared Extra long balloons are used for

balloon dilation of the aortic valve For smaller patients

(and usually smaller 10 and 12 mm diameter balloons), a

4 cm balloon length is used, and for larger patients (and

usually larger balloon diameters), 6–8 cm long balloons

are used when available The combination of the

double-balloon technique, the use of super stiff wires, and the use

of longer balloons, virtually eliminates the problem of the

balloons squirting or bouncing in and out of the valve and

further damaging the valve during the balloon inflations

The combined inflated diameters of the two balloons for a

double-balloon dilation is equal to a maximum of 1.2 to 1.3

times the maximum accurately measured diameter of the

aortic annulus If a single-balloon technique is used, the

single balloon diameter to start with is no more than 0.9 to

1 times the diameter of the accurately measured annulus

For the usual balloon dilation of the aortic valve, the

balloons undergo a standard preparation in order to clear

them completely of any air before introduction into the

sys-temic circulation A “minimal balloon preparation”

simi-lar to the balloon preparation in very small and/or

critically ill infants is used when there is concern that the

standard balloon prep would increase the deflated

bal-loon profile enough to necessitate a larger arterial sheath

The “minimal balloon preparation” is intended to clear a

balloon of air completely, but at the same time not to

“unfold” it from its “factory wrap” around the catheter

With the prograde aortic catheter in place across thevalve and the dilation balloon(s) prepared, the inguinalareas around the arterial puncture sites are re-infiltratedliberally with 2% xylocaine The indwelling arterial can-nulae are replaced with sheath/dilator sets that willaccommodate the balloons chosen for the dilation Anend-hole catheter that accommodates a 0.035″ guide wire

is passed retrograde around the arch and into the aorticroot from one of the arterial sheaths

Crossing the stenotic aortic valve with the wire(s) andthen positioning the catheter(s)/wire(s) securely andsafely in the left ventricle is often the most difficult part ofthe aortic valve dilation procedure The aortic root is oftenvery dilated and distorted, with the stenotic orifice of thevalve located very eccentrically

The course of the prograde catheter passing through thestenotic valve from the left ventricle into the aorta pro-vides the most reliable technique for identifying the exactposition and “direction” of the stenotic orifice, and is avaluable asset for crossing the stenotic aortic valve fromthe retrograde approach The course of the catheter pass-ing through the valve orifice provides a visible “guide” tothe actual course from the left ventricle, through the nar-row and otherwise invisible orifice, and into the aorta

In the absence of a prograde catheter through the valve,the valve leaflets themselves and the valve orifice are

“invisible” on the fluoroscopy and are only identified bycomparing the fluoroscopic image to the “jet” of contrastpassing through the orifice on the previous angiographicrecording The “freeze frame” of that recording is used as

a guide in “finding” the valve orifice during the grade approach

retro-A torque-control catheter with a preformed, slightlycurved tip, together with a steerable wire with a slightlycurved soft tip, are used to maneuver across the valve Apreformed right or left coronary catheter is most useful fordirecting the tip of the wire toward the aortic valve orifice.Occasionally the preformed retrograde catheter itself can

be directed purposefully and precisely along the course ofthe prograde catheter and through the valve orifice.Usually crossing the stenotic orifice requires the use of thecombination of several catheters and wires, even with aprograde catheter serving as a guide Rotating the shaft

of a catheter clockwise or counterclockwise with the preformed tip positioned in the aortic root, moves the

catheter tip (and wire) anteriorly or posteriorly Moving

the shaft of the catheter forward and backward moves the curved tip of the catheter (and, in turn, the wire tip)

from side to side in the aortic root.

The prograde catheter passing through the valve orificeprovides the exact “route” through the valve orifice,which is visualized simultaneously as the wire is manipu-lated through the retrograde catheter The combination

of the known location of the orifice, which is delineated

precisely by the course of the prograde catheter through

the orifice, and the precise control over the direction of the

wire tip, allows the operator to maneuver the tip of the

wire purposefully, precisely along and immediately

adja-cent to the prograde catheter In contrast to the rapid,

repeated maneuvers used during a “blind” probing with a

wire at a stenotic aortic valve, the maneuvers with the

catheter and the wire when “following along the prograde

catheter” are carried out slowly and purposefully The tip

of the wire is observed frequently on both PA and lateral

fluoroscopy as the wire is “tracked along” the prograde

catheter This maneuvering of the wire into the ventricle is

still not “automatic” and may take several attempts, each

with a readjustment of the angle of approach of the wire to

the valve Occasionally, when the angle of the valve orifice

is very distorted, it is necessary to change to a catheter

with a completely different preformed curve at the tip in

order to angle the wire properly at the orifice A very soft

tipped wire can create a problem with this technique

With a very tight stenosis, the high velocity of the jet of

blood through the orifice, literally, blows the tip of a very

soft tipped wire away from the orifice When this problem

occurs repeatedly, a wire with a slightly stiffer tip is used

to accomplish the retrograde crossing of the valve The

technique of tracking along the “adjunct” prograde

catheter to guide the retrograde wire through the valve

represents the most definitive technique available for

cross-ing the stenotic aortic valve from a retrograde approach

Some operators prefer not to go through the extra

maneuvering for the adjunct prograde catheter technique,

and occasionally the prograde catheter from the left

ventricle into the aorta cannot be used or accomplished,

especially in very small, very sick infants Various other

“tricks” are described for crossing the stenotic aortic

valves from the retrograde approach without the adjunct

prograde catheter Most of the techniques first involve the

positioning of a precurved, end-hole catheter retrograde

into the aortic root An attempt is often made using the

retrograde catheter itself to probe at the “invisible” orifice

A soft tipped catheter is “bounced” gently, rapidly and

repeatedly off the valve and occasionally even “backs”

through a tight orifice with a 180° loop formed on the

catheter A catheter with a stiff tip should never be used

with this technique A stiff catheter tip repeatedly

bounced off of a stenotic valve can easily create an orifice by

perforating a leaflet!

When there is no prograde catheter through the valve, a

very soft tip, small diameter, spring guide wire is

maneu-vered toward the valve through a precurved, end-hole,

retrograde catheter, somewhat similar to the catheter/

wire maneuvers just described The main difference is that

the wire is advanced rapidly and repeatedly, in and out of

the catheter tip while the angle of the catheter tip is

changed repeatedly This, in turn, bounces, or backs the

wire tip in and out of the aortic sinuses until the tip or aloop of the wire eventually falls (somewhat accidentally)through the valve opening Since the valve leaflets and the

orifice are not visible at all, this requires rapid, but patient,

repetitions rather than any particular skill The more

repetitive “probes” at the valveaeach with a change in the

direction of the wire by changing the catheter tip position

athe more likely is the chance of crossing the valve This

is the opposite of tracking along a known course of a prograde catheter through the valve and is an instancewhere slow, meticulous catheter and/or wire manipula-

tions definitely are not indicated Slow maneuvers in this

situation increase the radiation used and, at the sametime, decrease the “chances” of hitting the valve orificeper unit time of fluoroscopy used If one particularwire/catheter combination does not accomplish crossingthe valve after several minutes of rapid “probing”, thewire and/or the catheter is/are exchanged A similar

“probing” at the valve with the new catheter/wire bination is used

com-Although a very soft tipped wire is unlikely to perforate

a valve cusp, there are potential problems associated with

the rapid probing technique With the rapid in and outmovements of the wire, occasionally the wire dropsthrough the valve, but is pulled back and out of the ventri-cle before the position is recognized because of the rapid-ity of the maneuvering This is even more likely in thepresence of a markedly distorted aortic root/valve or anunusual course into the ventricle A more serious problem

is the inadvertent and unrecognized cannulation of acoronary artery with the wire/catheter As the aortic root

is probed, the wire passes from the coronary sinus into

a coronary artery often more easily than through thestenotic valve In the presence of a markedly distorted aor-tic root, the abnormal wire position in the coronary arterycan go unnoticed When the soft tipped wire only isadvanced into the coronary artery, it usually does not create a problem, but if the wire is advanced far into thecoronary, particularly if the catheter is advanced over thewire deep into the coronary thinking it is in the ventricle,the coronary artery can be damaged The treatment forthis potential problem is awareness and prevention.Perforation of an aortic valve leaflet during the retro-grade probing of an aortic valve is a constant potential

problem When the tip of the retrograde catheter is deep into, or actually becomes buried in the aortic sinus and

then a wire is advanced out of the catheter tip, the wiredoes not have room to “buckle” or bend and the wire isthen more likely to perforate directly through the valve

tissue in front of itaparticularly the tissue of a thin valve

leaflet If a valve leaflet is perforated by the wire and then

a dilation balloon is passed over the wire through the foration, the valve will be destroyed rather than dilated!The stiffer the wire and/or the catheter that is used for the

per-retrograde probing of the aortic valve, the less ability the

wire and/or catheter has of “buckling away” from the

aortic sinuses and the greater the potential for this type of

leaflet perforation Even the “soft” tip of a “standard”

0.025″ spring guide wire is very stiff for the first few

mil-limeters as it extends out of the tip of a catheter

A Terumo™ (or Glide™) wire creates an equal or

prob-ably greater problem of perforation of the aortic leaflets

when it is used to pass retrograde across an aortic valve

Terumo™ wires become much stiffer and much sharper

when they have no room to “buckle” between the tip of

the catheter and the structure/tissue it is attempting

to cross The Terumo™ wire also “glides” through the

tissues easily once it does perforate, and as a consequence

an abnormal course of the wire within tissues can go

unrecognized

The “blind” retrograde probing technique for crossing

the valve usually and eventually is successful, however, it

has obvious drawbacks Crossing the valve depends more

on chance and multiple repeated attempts than on any

skill The use of biplane imaging to help “identify” the

location of the orifice in “three dimensions” is essential to

the success of this as well as all of the other techniques for

crossing the aortic valve Even when the valve, and

particu-larly the orifice of the valve, are not visible, the second

plane of fluoroscopy allows the operator to know when

the catheter/wire is repeatedly probing in a totally

inap-propriate or non-productive area of a valve sinus

Once the left ventricle has been entered with the

retro-grade catheter and/or wire using whatever combination

of retrograde wires, special catheters or special curves

happen to work most effectively in the particular patient,

a soft, curved tipped, spring guide wire is advanced

retro-grade as far as possible into the ventricle When this wire

has been secured in the ventricle, an angled, end-hole

catheter is advanced over the wire into the ventricle With

a combination of pushing and backing maneuvers of both

the wire and the catheter, the tip of the retrograde catheter

in the ventricle is deflected and directed 180° back toward

the aortic valve When the angled end-hole catheter

can-not be directed fairly expeditiously back toward the aortic

valve, the original angled catheter is exchanged for a

pig-tail catheter over the original wire positioned in the left

ventricle Once the pig-tail catheter passes over the wire

and the pig-tail curve is positioned securely in the left

ven-tricular apex, the original wire is removed and replaced

with the larger, long floppy tipped, preformed, stiff,

exchange length wire, which should almost automatically

point toward the left ventricular outflow tract when it is

advanced out of the catheter tip

The largest diameter exchange wire that the balloon

catheters chosen for the dilation will accommodate is

introduced at this time In larger patients, the exchange

wire is a 0.035″, Super Stiff™ exchange length wire with

a long floppy tip This wire should have a “J” or, even, a

> 360° pig-tail curve formed manually at its distal floppy tipand a second more proximal, smooth, but short 180° curveformed at the “transition area” between the rigid part andthe floppy portion of the wire The preformed 180° curve

at the transition area of the wire will allow the stiff portion

of the wire to be completely across the valve when the180° curve at the transition area is seated in the apex of theventricle Either the original retrograde, angled, end-holecatheter looping 180° toward the outflow tract or the pig-tail catheter in the apex of the left ventricle directs the tip

of the Super Stiff™ wire back toward the left ventricularoutflow tract and allows the 180° curve on the stiff portion

of the wire to “seat” in the apex of the left ventricle The tip

of the wire is then directed back toward the LV outflowtract or even back across the aortic valve

When the double-balloon aortic dilation technique isused, the catheter is left in position over the first wire and a slow flush is maintained around the wire while thesecond wire/catheter is positioned5 Once the first stiffwire is in a stable position, the opposite groin is infiltratedliberally with xylocaine A second sheath/dilator set isintroduced into the opposite femoral artery An angled,end-hole catheter, identical to the catheter which was ini-tially used to cross the valve, is introduced into the secondarterial sheath and passed retrograde around the arch.The second catheter is maneuvered retrograde throughthe orifice and into the left ventricle “following” the firstcatheter/wire precisely while using the course of the firstwire/catheter through the valve orifice to serve as a vis-ible guide for introducing the second wire even if anadjunct prograde catheter was not used Once the secondwire has passed into the ventricle, the angled end-holecatheter is advanced into the ventricle and curved backtoward the outflow tract similar to the positioning of thefirst catheter When an 180° curve cannot be formed in theventricle with the angled end-hole retrograde catheter, it

is replaced with a pig-tail catheter, which is positioned inthe left ventricular apex adjacent to the first wire A sec-ond teflon-coated stiff exchange wire is pre-shaped, ident-ical to the first exchange wire, passed through the secondcatheter, and positioned in the left ventricle adjacent toand in a similar position to the first wire

Once the two stiff wires are in a satisfactory, stable position within the ventricle, the end-hole catheters areremoved over the wires and the previously prepared bal-loons are introduced over the wires It is important thatthe wires are observed continuously and maintained pre-cisely and securely in their positions during the introduc-tion of the balloons through the sheath and during theprocess of advancing the balloon catheters retrogradearound the arch The portions of the wires that are outside

of the body are maintained straight and are fixed against afirm structure on the table (or against the patient’s leg)

while the wires and the balloon catheters within the body

are observed frequently with fluoroscopy The wires

out-side of the body are adjusted in or out slightly in order to

keep the left ventricular wire loops from being withdrawn

from, or pushed further into (through!) the ventricle

dur-ing the various manipulations of the balloon catheters

This is important particularly when the balloon catheters

are being maneuvered next to each other The balloons are

maneuvered over the wires to a position just above the

aortic valve The two wires are advanced toward the apex

of the ventricle until all “slack” is out of the wires and the

wires are pushed against the outer circumference of the

course from the descending aorta, around the aortic arch,

and into the ascending aorta

Once all of the preparations are ready for the controlled

pressure inflation of the two balloons, the two wires are

fixed in position and the balloons are advanced one at a

time over the wires and across the aortic valve The

posi-tion of the balloons in the aortic valve is compared with

the “freeze frame” image of the valve With the balloons in

their proper position, the area of the valve leaflets should

be exactly in the center of the two markers at the end of

each balloon This positions the center of the parallel

sur-faces of the balloons at the narrowest portion of the valve

If the balloons are unstable in the initial position across the

valve, they are advanced further over the wires toward

the apex of the ventricle while maintaining the parallel

walls of the balloons in the narrow portion of the valve

and keeping the curved wires in the apex of the left

vent-ricle This readjustment is easier and safer when using

longer dilation balloons If a balloon is too far within the

ventricle, the wire is advanced gently in order to push the

balloon back rather than withdrawing the balloon This

maneuver maintains the wires at the “outer

circumfer-ence” of the course around the arch and maintains better

control over the wires

In very severe valve obstruction, the passage of the first

deflated balloon across the narrow orifice can cause a

sud-den and dramatic deterioration in the patient’s

hemody-namics In this circumstance, the first balloon is positioned

rapidly in the valve, inflated, deflated and withdrawn

back into the aortic root The patient is allowed to stabilize

(or is resuscitated) before attempting to position the

sec-ond balloon The subsequent positioning of the two

bal-loons is accomplished as rapidly as possible and followed

immediately by simultaneous rapid inflation/deflation of

the two balloons All inflations/deflations of the balloons

during a dilation procedure are recorded on either biplane

angiography or “stored fluoroscopy”

During the dilation, the balloons are inflated until the

indentations or “waists” in the balloons caused by the

stenotic valve disappear or until the balloons reach their

maximum advertised pressure, whichever comes first As

soon as the balloons reach this full inflation, they are

deflated as rapidly as possible During the balloon inflation

in the aortic valve, almost total obstruction of all cardiacoutput is created by the fully inflated balloon(s) The heartrate slows, the systemic arterial pressure (monitoredthrough the prograde arterial catheter still passingthrough the valve or through the side arm of one of thearterial sheaths) drops, and the left ventricular pressure(monitored through the transseptal sheath still positioned

in the ventricle) increases markedly With a successful

dila-tion of the valve, these hemodynamic parameters rapidly

return to “normal” once the balloons are deflated, ever, the balloons should be withdrawn rapidly over thewires and back into the aortic root to be sure of, and tofacilitate, this recovery

how-The inflation/deflation of the balloons is repeated eral times, changing the positions of the balloons beforeeach subsequent inflation by moving them in and out ofthe valve slightly and, if possible, changing their relativeanterior/posterior/lateral relationships in the process.With the pressures available through the long sheath inthe left ventricle and through the prograde catheter posi-tioned in the aorta, the hemodynamic results of the dila-tion are known as soon as the balloons have been deflatedand without moving the balloon catheters The end point

sev-of the dilation is the absence sev-of any “waist” on the

bal-loons during the initial phase of subsequent inflations and

a reduction of the gradient across the valve to less than

25 mmHg The left ventricular pressure should approachnormal or near normal as monitored by the indwellingtransseptal sheath(s)

Occasionally, the heart rate and blood pressures do notreturn to normal very rapidly after the inflation/deflation.When this return of heart rate/blood pressure is slow, orappears non-existent, if not already accomplished, the bal-loons are withdrawn over the wires, out of, and awayfrom, the valve The patient is given atropine through theleft ventricle sheath and if necessary given several exter-nal manual compressions to stimulate cardiac function.With even partial relief of the aortic obstruction the heartrate and pressure do return

Before making the final post-dilation hemodynamic

measurements, both balloons are withdrawn back overthe wires into at least the descending aorta so that the only

“equipment” passing through the valve is the two grade wires and the prograde balloon catheter, which ispositioned in the aorta The residual gradient across thevalve is recorded from the pressure in the left ventricle(through the sheath) and the pressure in the aorta(through the prograde catheter) and/or one of the femoralartery pressures through the side arm of the femoralartery sheath The pressure gradient and the contour ofthe pulse curves give an excellent immediate indication ofthe results of the procedure before the removal of anycatheters or wires With a very successful relief of the

retro-obstruction, the left ventricular systolic pressure

approx-imates the aortic systolic pressure, the left ventricular

end-diastolic pressure is less than 15 mmHg, the gradient

across the aortic valve is abolished or reduced to less than

20 mmHg and there is little or no aortic valve regurgitation

When mild, or no aortic regurgitation is produced, the

pulse pressure is 25–30 mmHg even with the prograde

catheter and the wires still across the valve An aortic root

angiocardiogram to assess aortic regurgitation is recorded

with injection through the prograde catheter This

injec-tion helps to assess the aortic regurgitainjec-tion, particularly if

there is a wide pulse pressure If there is significant aortic

regurgitation but good relief of the obstruction, nothing

further therapeutic is performed in the catheterization

laboratory at this time If there is a significant residual

gradi-ent and significant aortic regurgitation as demonstrated by

the post-dilation pulse pressure or the aortogram, the

wires are removed from across the aortic valve in order

to assess the aortic regurgitation more accurately

Occa-sionally, a stiff wire is forced against one side of the

annu-lus and “holds the valve open”, creating false aortic valve

regurgitation Once the wires across the annulus have

been withdrawn, the aortic regurgitation is reassessed

with repeat pressure measurements and a repeat aortic

root aortogram The prograde catheter passing through

the valve alone does not, or very rarely, produce

signi-ficant aortic regurgitation However, if signisigni-ficant aortic

valve regurgitation is demonstrated from the injection

through the prograde catheter, the prograde catheter is

withdrawn into the ventricle and a repeat aortic root

angiocardiogram performed with an injection in the aortic

root through a retrograde catheter If there is still

signific-ant aortic regurgitation, regardless of any residual gradient,

no further dilation is performed

If dilation with the original balloons did not produce

sufficient relief of the obstruction, but also did not produce

significant aortic valve regurgitation, the angiographic

images of the balloon inflations and the post-dilation

angiograms are reviewed The diameters of the inflated

balloon(s) and valve annulus are re-measured accurately

on these angiograms of the inflations If angiographically

the balloon diameters are the same or smaller than the

diameter of the annulus, the combined balloon diameters

are increased up to 1.2 times the annulus diameter and the

dilation repeated If the balloon diameters are 1.2 times (or

more) larger than the aortic annulus on the angiographic

images of the balloon inflation, no further dilation is

attempted If a single balloon is used for the dilation and

the balloon is exactly the same diameter as the annulus on

the inflation images, the balloon diameter is increased by

at most 10% and the dilation is repeated

When the transseptal sheath and prograde catheter

were not used during the procedure, there are several

alternative techniques to record the postdilation pressures

before the wires are removed A separate, new transseptal

procedure can be performed to enter the left heart and leftventricle The left ventricular pressure through thetransseptal catheter is compared with the femoral arterypressure measured through the side arm of one of thefemoral artery sheaths Another alternative technique is toremove one balloon dilation catheter over the wire Thewire is maintained in the left ventricle and the balloondilation catheter is replaced over this wire with a Multi-Track™ catheter The Multi-Track™ catheter is advancedretrograde over the wire all the way to the left ventricle.Pressures from the Multi-Track™ catheter can berecorded from any location along the course of the wireduring either the introduction or the withdrawal of theMulti-Track™ catheter and with the wire remaining inplace Angiograms can also be recorded at any locationthrough an angiographic Multi-Track™ catheter By usingthe Multi-Track™ catheter, the retrograde wire is still inplace in the ventricle without any further manipulations

of the wire if a new balloon dilation catheter must be duced for a repeat dilation

intro-The third, and least attractive alternative to either ofthese previous techniques for reassessment of the hemo-dynamics post-dilation is to withdraw one of the retro-grade balloon dilation catheters over the wire andcompletely out of the body while leaving the wire in theleft ventricle The balloon catheter is replaced with an end-hole diagnostic catheter, which is passed over the wire,retrograde, all of the way to the left ventricle The wire isthen removed completely The left ventricular pressure ismeasured through this catheter and compared with thefemoral arterial pressure measured through the side arm

of the other arterial sheath If the simultaneous pressuresfollowing the dilation demonstrate an unsatisfactoryrelief of the obstruction, an aortic root aortogram to assess

aortic regurgitation cannot be obtained without

with-drawing this catheter out of its position in the ventricle

Once the catheter is withdrawn and if the dilation does

need to be repeated, one retrograde wire still is passingthrough the valve and into the ventricle This wire serves

as a “guide” along which the wire/catheter is directedduring the reintroduction of the retrograde catheter backinto the ventricle Once the catheter is positioned back

in the ventricle, the stiff exchange wire is re-advanced

through this catheter and repositioned in the ventricle for

introduction of the new balloons

Once it is determined that a satisfactory relief of the aortic obstruction has been obtained, the balloon catheters are withdrawn slowly over the wires and out of the vessels As they are withdrawn, the balloon cathetersare rotated in the direction of the balloon folds and

the negative pressure to the balloons is released during

the withdrawal through the aorta and out through thesheaths

Occasionally the retrograde wires, with their

pre-formed loops and curves, become entangled in the

ven-tricular structures Once the balloon catheters have been

withdrawn out of the sheaths, end-hole catheters are

advanced over the wires and into the ventricle While

observing on fluoroscopy, the wires are removed through

these catheters Withdrawing them through catheters

pre-vents the wires from damaging or disrupting chordae or

papillary muscles around which they may have been

entrapped

There is an additional technique for the guaranteed

introduction of a balloon dilation catheter retrograde

across even the most stenotic aortic valve This technique

is used only when the aortic valve is particularly difficult

or impossible to cross with any of the previous retrograde

catheter/wire techniques This technique is most suitable

for a single-balloon dilation technique but can be used for

a dilation using double balloons The technique is a

varia-tion of the use of the prograde catheter along with the

ret-rograde technique, but does add some additional complex

maneuvering to the procedure An end-hole, floating

bal-loon catheter is introduced prograde into the left ventricle

through a long transseptal sheath The end-hole balloon

catheter is advanced (floated) prograde across the aortic

valve and into the descending aorta An extra long (400 cm),

exchange length, spring guide wire is passed through

the prograde catheter and into the descending aorta A

snare catheter is introduced retrograde from a femoral

artery and the distal end of the prograde wire, which was

advanced through the prograde catheter, is snared with

the retrograde snare and withdrawn out through the

femoral artery sheath This produces a “through and

through” wire from the femoral vein to the right atrium,

left atrium, left ventricle, through the aortic valve, into the

aorta, and out through the femoral artery The desired

bal-loon dilation catheter is introduced over the arterial end of

the wire, through an arterial sheath, advanced retrograde

over the through and through wire and through the aortic

valve For a double-balloon technique this procedure is

repeated from the other femoral artery and a second

femoral vein The position(s) of the balloon(s) in the aortic

valve is/are adjusted with the catheters and wires and the

dilation of the valve carried out similarly to any other

bal-loon dilation of the aortic valve

This technique guarantees that the balloon dilation

catheters cross the aortic valve orifice and provides the

maximum control over the position and movement of the

balloons during the inflation/deflation At the same time

it does add some complexity to the procedure The

femoral artery and left ventricular pressures can be

mea-sured simultaneously before, during and immediately

after the dilation through a side arm of the transseptal

sheath and a side arm of the arterial introductory sheath

since, in order to accommodate the passage of even the

deflated dilation balloon, the sheath lumen is always

larger than the shaft of the balloon dilation catheter.

With the through and through wires in place, the loon dilation catheters are easily exchanged or removed.Once the dilation of the aortic valve is completed success-fully, the balloon dilation catheters are withdrawn overthe wires and replaced with end-hole catheters, which areadvanced retrograde over the wires and into the left ven-

bal-tricular apex Once the catheters are in place over the wires

the wires are withdrawn through the long sheaths fromthe venous end The retrograde catheters prevent the stiffwires from cutting intracardiac structures when they

“tighten” as they are withdrawn

When the catheters and wires have been withdrawn out

of the sheaths, more local anesthesia is administered ally around the sheaths at the arterial puncture sites, andthe sheaths are withdrawn Direct manual pressure isapplied over the arterial puncture sites to stop local bleed-ing Either the dorsalis pedis or the posterior tibial pulse inthe same extremity as the puncture is palpated simultane-ously while holding pressure on the artery, being sure thatthe peripheral pulse is not obliterated by the pressureapplied to obtain the hemostasis Pressure is maintainedbalancing the control of bleeding vs the peripheral pulseuntil hemostasis is achieved The systemic heparin is notusually reversed, so achieving hemostasis safely after theremoval of a large sheath can take up to an hour or more

liber-After hemostasis is achieved, a very light bandage just to

cover the puncture site is applied The bleeding should becontrolled before the bandage is applied A tight compres-

sion pressure bandage is not used over the artery The

bandage is left in place for 4–6 hours The patient isobserved in a monitored recovery bed for a minimum offour hours and until they are fully awake Particular atten-tion is paid to the puncture site and the pulses in the

extremity peripheral to the puncture site The “Foley”

catheter is left in place until males are awake and untilfemales are moved out of the recovery ward Patients whoundergo aortic valve dilation are observed in the hospitalovernight On the assumption that all of the adrenergicstress and any volume load from the catheterization aredissipated by the following morning, these patients usu-ally undergo an echocardiogram before discharge on theday following the catheterization This echo informationserves as the baseline, non-invasive value for subsequentfollow-up evaluations The patient is discharged with no

imposed limitations because of the catheterization.

Infant and/or critical aortic stenosis dilation

The diagnosis of aortic stenosis is made from the clinicalfindings and is based more on the appearance of the valve

by echocardiogram and the associated poor left lar function rather than on a “gradient”4 Dilation of aortic

ventricu-stenosis in the newborn or small infant is one of, if not

the most difficult and dangerous procedures performed

by pediatric interventional cardiologists The dilation of

infant aortic stenosis is not just a “small version” of any

other aortic valve dilation The newborn or small infant

requiring treatment of aortic stenosis is usually very sick,

often is on prostaglandin and requires inotropic support

before and during the valve dilation procedure The

vas-cular access is small, partivas-cularly in proportion to the

sheaths, catheters, wires and balloons that are available

for small infants

These patients usually do have a patent interatrial

com-munication allowing the introduction of a prograde

venous catheter into the left ventricle A left ventricular

catheter remaining in place throughout the procedure is

invaluable for pressure monitoring and, occasionally, for

a left ventricular angiocardiogram In the very sick and

small infant, once the left ventricle is entered with the

pro-grade catheter, this catheter is not advanced further into

the aorta at this time unless a prograde approach for the

dilation is anticipated When there is no naturally

occur-ring atrial communication, the decision is made at the

onset of the procedure as to whether acquiring the

hemo-dynamic information from the left ventricle before it is

entered retrograde is worth the extra effort and slightly

increased risk of a transseptal puncture in a very small

infant

With meticulous attention to detail, patience, very

delic-ate technique, and some special instrumentation,

percu-taneous entry into a femoral artery essentially always is

accomplished, even in small infants Small, sick infants are

the patients in whom the special 21-gauge percutaneous

needles and the extra floppy tipped 0.018″ wires are

invaluable for entering the artery (Chapter 4) A

“single-wall” puncture technique is always attempted Once the

artery is cannulated with the guide wire, the surrounding

area to the puncture site is re-infiltrated liberally with

local anesthesia A 3- or 4-French (depending upon the

balloon to be used), fine or “feathered” tipped sheath/

dilator set is introduced into the artery Once the sheath is

secured in the artery and cleared of any air, an end-hole,

pre-curved right coronary catheter is introduced through

the sheath and advanced retrograde to the aortic root

The aortic pressures and aortic root angiocardiograms

are performed with the retrograde catheter This catheter

allows baseline pressure measurements, and satisfactory

aortic root aortogram(s) can be obtained with end-hole

catheters in these small infants At the same time, an

angled, end-hole catheter is the most useful for

manipula-tion of the guide wire across the stenotic valve for the

sub-sequent dilation, all without an unnecessary exchange of

catheters Only one arterial catheter is necessary since a

single-balloon, retrograde approach is used for dilation of

the aortic valve in small infants However, if the other

femoral artery is entered inadvertently during the ture of the vessels, it is cannulated with a 20-Gauge, teflonQuick-Cath™ for continual arterial monitoring through-out the procedure

punc-The “venous” catheter previously positioned in the leftventricle along with the arterial line allows recording ofsimultaneous left ventricular and aortic pressures This

helps to confirm the severity of the aortic stenosis,

how-ever, in these infants with poor left ventricular function,the gradient, particularly in very severe aortic stenosis, isoften minimal A left ventriculogram is not usually neces-sary and potentially is dangerous in a critically ill infant If

a ventriculogram is desired, it is recorded with injection inthe left ventricle through the prograde catheter When theleft ventriculogram is accomplished before the valve is

crossed, it helps to localize the area of the valve orifice.

The diameter of the aortic valve annulus is measuredvery accurately from the aortic root injection or the leftventricular angiocardiogram Once the valve measure-ments are obtained, the appropriate dilation balloon for

the aortic valve dilation is chosen and prepared before an

attempt is made at crossing the valve The balloon chosen

is equal in diameter to the aortic annulus measured at thevalve hinge points The preferred balloons for very smallinfant and neonatal aortic valve dilations currently are thevery small Tyshak Mini™ (NuMED Inc., Hopkinton, NY)balloons The Tyshak Mini™ balloons up to 8 mm indiameter pass through a 3-French sheath while the 9 and

10 mm Mini™ balloons require a 4-French sheath TheMini™ balloons, however, accept only a 0.014″ wire TheHi-Torque Iron Man™ wire (Guidant Corp, Santa Clara,CA) is as effective a wire as any available for supportingthese balloons The dilation balloon is prepared using a

“minimal prep” technique The stenotic aortic valve iscrossed only after the balloon has been prepared and isready to be introduced These infants are so precariousthat the 3- or 4-French catheter alone crossing the stenoticorifice is enough to occlude the orifice and cause the infants

to decompensate acutely and occasionally irreversibly

A 3- or 4-French, pre-curved right or left Judkins™coronary catheter or a 3- or 4-French curve-tipped multi-purpose catheter is advanced retrograde into the aorticroot from the femoral artery To cross the aortic valves in aneonate, a 0.014″ or a 0.018″ very floppy tipped exchange

length, torque-controlled guide wire is used The wireused depends upon what the balloon chosen for the dila-tion will accommodate When a 0.018″ wire can be used, aPlatinum Plus™ (Boston Scientific, Natick, MA) or a V-18Control™ (Boston Scientific, Natick, MA) wire is veryuseful both for crossing the valve and for supporting thedilation balloon across the valve A very slight curve isformed at the tip of the wire to allow changes in directionwhen torquing the wire The wire is advanced through thepre-curved catheter positioned in the aortic root

Crossing the aortic valve in the neonate is similar to

the “blind” crossing in an older patient except that all

structures are much smaller and, in turn, all catheter

manipulations are much finer Occasionally, the

pre-curved catheter will pass through the stenotic orifice

when maneuvered directly at the valve Crossing with the

catheter is attempted several times while simultaneously

rotating and moving the catheter in and out in the aortic

root When the catheter does not cross the valve, the

catheter tip is positioned at least one centimeter above the

valve and the very soft tip of a fine guide wire is

manipu-lated out of the catheter The wire is directed toward the

aortic valve orifice by almost continuously rotating the

catheter while simultaneously moving both the catheter

and the wire to and fro Multiple, rapidly repeated, short

probes are made with the wire toward the aortic valve

orifice rather than any slow, methodical maneuvers The

exact location of this orifice really is not known unless

another wire or catheter is already passing through the

valve The more “probes” that are made with the wire

during the simultaneous, multiple changes in the angle/

direction of the wire, the more likely is the tip of the wire

to cross the valve If the wire does not cross the valve after

several minutes of trying with the first angled catheter

and wire, the catheter and/or the wire are replaced with

either the right or left coronary catheter or the

multipur-pose catheterawhichever was not used initiallyaand the

“probing” with the wire is repeated during continual

changes in the direction of the catheter tip Eventually,

more by chance than skill, the wire crosses the valve into

the ventricle

Once the wire crosses the valve, it is advanced as far as

possible into the ventricle, hopefully even looping the soft

tip of the wire within the apex of the left ventricle With

the wire advanced as far as possible into the ventricle, the

catheter is advanced over the wire to the ventricular apex

If the infant remains stable with the end-hole catheter

passed through the valve, the catheter is fixed in the

ven-tricle and the wire is removed Preferably, the original

fine, soft tipped wire is replaced through the catheter

posi-tioned in the left ventricle with a stiffer, exchange length

wire of the largest diameter that the prepared balloon will

accommodate The stiffer wire should be pre-shaped

before introduction into the catheter/ventricle A

“pig-tail” curve is formed on the long floppy tip of the new

guide wire and a 180° curve, which conforms to the cavity

size at the ventricular apex, is formed at the transition

zone of the wire between the long floppy tip and the

stiff shaft of the wire This specifically formed wire is

advanced through the catheter into the left ventricle The

pre-formed “pig-tail” keeps the wire from digging into

the myocardium as it is manipulated within the ventricle

The 180° curve at the transition area of the wire prevents the

stiffer wire from perforating the left ventricle and, at the

same time, directs the tip of the wire 180° back toward the left ventricular outflow tract This position allows the

stiff portion of the wire proximal to the curve at the

trans-ition area to be postrans-itioned completely across the valve and deeper within the ventricle With the wire maintained

in position, the catheter is removed and replaced with the already prepared balloon catheter The balloon is positioned precisely across the valve and an inflation/deflation is performed as rapidly as possible The inflation/deflation is recorded on biplane angiography or onbiplane “stored fluoroscopy”

During the inflation of the balloon, the left ventricularpressure increases, the systemic arterial pressure drops,and the infant develops bradycardia As soon as thedeflation of the balloon is complete, the balloon is with-drawn over the wire and out of the aortic valve On relief

of the obstruction, the infant’s heart rate returns and theleft ventricular pressure decreases toward normal Therapidity of the stabilization of the infant is a partial indica-tion of the success of the dilation The infant’s heart rateshould return to a rate faster than the baseline rate and theleft ventricular pressure should be lower than predila-tion A very sick infant may require some medical ormechanical assistance for return of the cardiac output

When the infant does not remain stable with even the small end-hole catheter across the valve, the original wire

used to cross the valve is stabilized rapidly and the

catheter is immediately withdrawn over the wire and out of

the valve orifice while leaving the wire in place The

end-hole catheter is rapidly replaced with the previously

pre-pared balloon dilation catheter, which is passed over the

wire and positioned across the valve as expeditiously, but

at the same time as accurately, as possible Dilation of thevalve is carried out with as rapid an inflation/deflation ofthe balloon as is possible The balloon inflation/deflation

is recorded on biplane, stored fluoroscopy or ically After the inflation/deflation, the balloon is immedi-ately withdrawn out of the valve, over the wire and into atleast the ascending aorta to allow the infant to stabilize.The wire is kept securely in place in the ventricle when-ever possible

angiograph-Once vascular access is obtained and the aortic valve iscrossed with a retrograde catheter, aortic valve dilationfrom the femoral route usually is very successful.However, femoral arterial access is the most difficult andthe most hazardous part of the procedure in the neonateand small infant The vessels are very small relative toeven the smallest catheters/dilating balloons available foraortic valve dilation As a consequence, arterial complica-tions are relatively common in this group of patients.Although extreme occlusive problems with necroticischemia of a limb are extremely rare, cool extremitieswith poor perfusion of the extremity immediately after

a retrograde catheterization are common and usually

represent compromise, if not total loss of the deep femoral

artery of the involved limb These patients usually acutely

regain perfusion and warmth of the extremity but often on

subsequent attempts at access, the deep femoral artery is

totally occluded or occasionally the patient has a relative

growth failure of that extremity As a consequence of the

femoral access problems several other routes for aortic

valve dilation have evolved

Carotid artery introduction for the retrograde

approach

Transapical balloon dilation of the aortic valve in neonates

set a precedent for direct collaboration between the

car-diovascular surgeon and the interventional cardiologist

for performing aortic valvotomies in critically ill infants

Because of the difficulties with arterial access and then

entering the ventricle from the femoral approach,

particu-larly with the earlier balloons, several centers performed

balloon dilation of the neonatal aortic valve in the

operat-ing room through a thoracotomy and a controlled, apical,

left ventricular puncture, but without the necessity of

car-diopulmonary bypass Although this approach avoided

cardiopulmonary bypass, it did not avoid deep general

anesthesia, the thoracotomy, the ventricular perforation,

and all of the inherent problems of these particular

proced-ures The improvement in balloons and balloon

tech-niques soon put this particular collaborative technique

to rest

An alternative, unique and, initially, seemingly radical

collaborative approach for aortic valve dilation was

devel-oped as a consequence of the ongoing technical problems

with balloon dilation of the infant aortic valve and, at the

same time, other vascular technology which had been

developing concurrently The continuing difficulties with

the arterial access site when using the femoral artery

approach in neonates and the persistent difficulties with

the catheter manipulation around the arch and across the

aortic valve from both the femoral artery and the

umbili-cal artery approaches made these approaches less than

ideal At the same time the expanded use of

extracorpo-real membrane oxygenation (ECMO) led to almost

“rou-tine” cut-downs and repairs of the carotid artery by pediatric

vascular surgeons

The combination of the persistent problems with the

femoral/umbilical catheter approaches and the proficiency

of the surgeons with the carotid cut-downs resulted in the

consideration of a carotid artery approach to the balloon

dilation of the aortic valve6 The carotid artery itself has

considerable appeal as an approach to the aortic valve Of

most importance the approach to the aortic valve from the

entrance into the carotid artery is a very short, very

straight shot! With this “straight line” from the right

carotid artery to the left ventricle, minimal catheter

manipulation is required to cross even a severely stenoticaortic valve and to enter the left ventricle with a wire orcatheter The carotid artery is approached and entered

by a cut-down procedure performed and repaired by avascular/cardiovascular surgeon The carotid approachcombined with essentially no vascular or central nervoussystem sequelae when a skilled vascular surgeon exposesand repairs the artery, makes the carotid approach seemlike the ultimate solution to a major problem

Patients undergoing a carotid cut-down approach foraortic valve dilations are anesthetized with general anes-thesia to ensure that they are maintained absolutely stillthroughout the procedure They undergo endotrachealintubation for control of their respiration and to keep thehead and face out of the “operating” field in the neck Thecarotid approach for the dilation is usually used in con-junction with a prograde catheter from a systemic veinand a separate indwelling femoral arterial monitoringline The majority of the hemodynamic and anatomicinformation is obtained through these lines before thecarotid cut-down is initiated The venous catheter isadvanced through the patent foramen ovale (PFO) andinto the left ventricle in almost all of these infants Thevenous catheter and femoral arterial line are introducedsimultaneously while the surgeon is introducing thesheath into the carotid artery and usually the progradecatheterization and femoral lines do not add any over-all time to the procedure The prograde catheter andindwelling arterial line actually simplify and add to thesafety of the procedure The venous prograde catheter inthe left ventricle and the separate indwelling femoral arte-rial line provide continuous left ventricular and systemicarterial pressure monitoring before, during and after thedilation without having to cross the aortic valve repeat-edly with a retrograde catheter

A vascular surgeon performs a cut-down on the neckover the mid portion of the right carotid artery and iso-lates the right common carotid artery A floppy tippedwire that will accommodate the balloon dilation catheter

is introduced into the artery either through a small sion performed by the surgeon or through a needle intro-duced by the pediatric cardiologist

inci-The surgeon introduces a short 4-French sheath/dilatorwith an attached back-bleed valve/flush port into thecarotid artery over the soft tipped wire, and advances

it just to the base of the carotid artery as observed onfluoroscopy All further introduction and positioning ofthe sheath tip are performed by the pediatric cardiologistand are visualized continuously on fluoroscopy If even ashort sheath is introduced to its hub in the carotid artery in

a small infant, the tip of the sheath extends to (or past) thearea of the aortic valve If the tip of the sheath does not

pass through the orifice of the valve, it potentially

pro-duces catastrophic damage to the aortic valve Rarely, the

sheath/dilator/wire passes into the descending aorta

from the right carotid artery cut-down and has to be

with-drawn and maneuvered specifically back into the aortic

root Alternatively, the wire may pass directly into the left

ventricle during its initial introduction When the sheath

is in the proper position in the ascending aorta, the dilator

and wire are removed and the sheath is cleared

meticu-lously of any air or clots before flushing The sheath is

secured in the artery by means of a purse string and

sub-cutaneous sutures so that the tip of the sheath is fixed at

least 1–1.5 cm above the aortic valve An aortic root

aor-togram is performed with an injection directly through

the sheath or through a catheter introduced into the

sheath Accurate measurements of the valve annulus are

carried out using one of the reference calibration

tech-niques described in Chapter 11, “Angiography” The

appropriate balloon for the valve dilation is chosen from

these measurements exactly as it is chosen for the femoral

approach The balloon is prepared with a “minimal prep”

in order to eliminate all air from the balloon

A soft tip exchange wire, with a very slight curve at

the tip, which will accommodate the prepared balloon

dilation catheter is introduced through the sheath The

wire is introduced either directly through the sheath or

through an end-hole catheter introduced into the sheath

first A catheter within the sheath provides more control

over the tip of the wire and allows this catheter to be

advanced over the wire into the ventricle as soon as the

wire enters the ventricle At the same time, the catheter

adds considerable “length” outside of the introductory

site into the carotid artery, and it extends well above the

infant’s head for the manipulations The wire is

manipu-lated through the aortic valve into the left ventricle This is

usually accomplished with only a few “probes” and

mini-mal readjustment in the direction of the wire tip Once

through the valve, the wire is advanced deep into the

ventricle until the stiff portion of the guide wire is entirely

across the valve The wire is fixed in position in the

ven-tricle while the catheter is removed over the wire from

the sheath

The balloon catheter is advanced over the wire, into the

sheath, and to the area of the valve The balloon is

cen-tered precisely across the valve annulus as previously

identified by angiography or as visualized on a

trans-esophageal, or even a transthoracic, echocardiogram, and

a rapid balloon inflation/deflation is performed The

inflation/deflation is recorded on a biplane angiogram or

on “stored fluoroscopy” The balloon is withdrawn over

the wire and back into the sheath immediately after it is

deflated As with any other aortic valve dilation, the

in-fant’s hemodynamics deteriorate during the balloon

infla-tion in the valve, but usually return rapidly to “normal”

(or better) with the deflation of the balloon and its

with-drawal from the valve When the prograde left ventricular

and indwelling femoral arterial lines are in place, thehemodynamic results of the dilation are available imme-diately The patient is allowed to stabilize while therecording of the inflation/deflation is reviewed particu-larly for the balloon position and the appearance/dis-appearance of a waist on the balloon When the infant’shemodynamics have stabilized, the balloon is reintro-duced across the valve and the inflation/deflation isrepeated at least one more time Before each reinflation,the balloon is repositioned forward or backward in thevalve slightly The balloon is observed for any persistent

“waist” on it during subsequent inflations, particularlyduring the very initial phase of the inflation After a successful dilation, no residual waist should appear onthe balloon, even during the early phases of subsequentinflations

When satisfied with the appearance of the inflationsand the resultant hemodynamics, the balloon is with-drawn over the wire and out of the sheath, and the sheath

is passively cleared very carefully of any air or clot The

balloon dilation catheter is replaced with an end-holecatheter, which is advanced into the ventricle over thewire that is still positioned in the left ventricle The wire isremoved slowly through the catheter, the catheter cleared

of air/clot and the simultaneous left ventricle and femoralartery pressures are recorded If a femoral line was not inplace or there was no prograde catheter in the ventricle,the pressures are obtained following the dilation by either

a pull-back of the end-hole catheter across the valve or,preferentially, with the left ventricular pressures obtainedthrough the catheter still positioned in the ventricle andthe arterial pressure obtained simultaneously from theside port of the carotid artery sheath In this case, thesheath which is in the carotid artery/aorta must be at least one French size larger than the catheter When the

stenosis is not relieved by the initial dilation and aortic

insufficiency is not significant, a wire is repositioned inthe ventricle (either through the catheter still in the ven-tricle or by manipulating a wire/catheter back through avalve), and the dilation repeated with a larger balloon orwith repositioning of the balloon If a very wide pulsepressure is recorded or massive aortic regurgitation isvisualized by echocardiogram, either the procedure isconcluded or the catheter is withdrawn into the aorta and

an aortic root angiogram is performed to verify the sence and amount of aortic regurgitation

pre-When the prograde catheter is already in the ventricle,the pressures are recorded simultaneously from thiscatheter, the femoral arterial line, and the sheath in theaortic root When there is no prograde catheter in the ven-tricle, an end-hole catheter is advanced over the wire intothe left ventricle, the wire is removed, and the pressurefrom the left ventricle is recorded through the catheterwith a simultaneous femoral artery pressure from the

femoral arterial line If the resultant pressure in the left

ventricle appears satisfactory compared to the femoral

arterial pressure, a “pull-back” pressure is recorded as the

catheter is withdrawn from the left ventricle into the aorta

A follow-up aortic root aortogram is recorded with

injec-tion through the “retrograde” carotid catheter The

deci-sion for any further ballooning of the valve is made

exactly as for other aortic valve dilations When satisfied

with the results of the dilation, or if significant aortic

regurgitation was created regardless of the residual

gradi-ent, the sheath is withdrawn from the artery and the artery

repaired meticulously by the vascular surgeon

There are growing data indicating that the retrograde

approach to the aortic valve from the carotid artery may

be the safest and, in turn, the preferred approach for

bal-loon dilation of the aortic valve in very small infants Once

the sheath is secured in the carotid artery, the carotid

approach represents the most expedient way of crossing

and dilating a severely stenotic aortic valve in an infant

The results of the dilation are comparable to other dilation

techniques and there are no reported acute

complica-tions from the properly performed carotid approach The

repaired carotid arteries have good Doppler flow

immedi-ately following the dilation and on short-term follow-up

of the carotid repairs Whether this technique is used

rou-tinely in any particular center depends upon the

availabil-ity and co-operation of the surgeon, the surgeon’s skill at

vascular access and repair, and the working relationship

between the surgeon and the interventional cardiologist

When all of these “elements” fall into place, this is the

pre-ferred approach to the dilation of critical aortic valve

stenosis in the newborn and small infant

Umbilical artery introduction for the retrograde

approach

In the newborn infant, at least one of the umbilical arteries

is potentially patent for up to a week (or more) after birth

In a newborn infant with severe aortic stenosis who

requires aortic valve dilation, an umbilical artery

ap-proach for the retrograde catheter provides a potential

arterial access without compromise of a femoral or the

carotid artery7,8 The newborn with severe aortic stenosis

should have a venous catheterization with a prograde left

heart cardiac catheterization After the first few days of

life, the umbilical vein often is not accessible, in which

case the usual femoral vein approach is used for the

venous catheterization

The infant with severe aortic stenosis usually is critically

ill and frequently already has an end-hole polyethylene

“umbilical artery” catheter positioned by the

neonato-logist in the abdominal aorta from one of the umbilical

arteries! In that situation, a fine, very small diameter, but,

preferably, relatively stiff, exchange length, teflon-coated

wire is passed through the umbilical catheter and as far

as possible into the thoracic aorta, ascending aorta

and, with the ultimate luck, even into the left ventricle.

Unless the wire ends up in the left ventricle, the ethylene umbilical artery catheter is replaced over this wire with a 4-French angled tipped (right coronary)catheter

poly-When there is no pre-existing umbilical artery line, the

umbilical cord stump is scrubbed very thoroughly and then

“amputated” parallel with and close to the abdominalwall This exposes the stumps of the two umbilical arteriesand the umbilical vein The two arteries are smaller indiameter, rounder and thicker walled than the single,larger diameter and irregular vein Usually, all three ofthese umbilical vessels are obliterated with thrombi, however, patency of the arteries can often be restored

by “probing” the arterial lumen with a small diameter,smooth and blunt tipped metal probe One edge of theexposed wall of the end of one of the arteries is graspedwith a small forceps and the occluded lumen of the artery

is probed with a very small, blunt, metal, vessel probe afew millimeters at a time until the probe passes severalcentimeters into the lumen The probe usually stayswithin the walls of the vessel as it dissects through thethrombus With the stump of the vessel opened in thismanner, an end-hole “umbilical artery catheter” is intro-duced into the channel that was created with the probe,and advanced into the newly opened vessel lumen whileplacing some “counter tension” on the exposed edge ofthe vessel with the forceps As the catheter is introduced

into the lumen, it is directed posteriorly and caudally

toward the posterior pelvis Once the catheter hasadvanced several centimeters into the artery, it is visual-ized on fluoroscopy to determine whether the catheter isbeing directed to the right or the left inguinal area Withthat information, the catheter is pushed in that directiontoward that groin and the “counter traction” on the

“stump” is pulled away from that direction

Once the catheter has advanced one to two centimeterswithin the artery, the vessel often seems to “open up” andallow the catheter to move more freely through the umbil-ical artery Simultaneously, there may be blood returninto the catheter Usually resistance is encountered inmaneuvering the catheter around the sharp 90–130° curve

at the junction of the umbilical artery and the iliac artery.Occasionally, advancing the umbilical catheter is facilit-ated by advancing a fine, floppy tipped, torque wire or a

fine, curved Terumo™ wire through, and slightly in

advance of, the umbilical catheter Once the umbilicalcatheter has advanced into the descending aorta, anexchange length wire is advanced further into the thoracicaorta, the ascending aorta and, as before, with consider-able luck, into the left ventricle If the wire does notadvance all of the way to the ventricle, the soft umbilical

catheter is removed over the wire and replaced with a

4-French right Judkins™ coronary catheter

From the descending aorta, the combination of the wire

and right coronary catheter is advanced/manipulated

around the aortic arch into the aortic root This maneuver

is often very difficult and requires several exchanges of

different wires and/or catheters Once the catheter has

reached the aortic root, the wire is removed, the aortic

pressure recorded, and a biplane aortogram is recorded

with the X-ray tubes angled to “cut the valve on edge”

(some degree of LAO–Cranial and RAO–Caudal) with

the two planes Accurate measurements of the valve

annulus are made using one of the various accurate X-ray

calibration techniques A “marker catheter” can be placed

in the superior vena cava adjacent to the aorta or even the

left ventricle when there is prograde venous access If

there is no venous line, a calibration marker catheter

can be inserted gently into the infant’s esophagus and

advanced to the area behind the cardiac silhouette as the

reference for the angiographic calibration system When

positioned just behind the center of the heart shadow, the

calibration marks on the catheter in the esophagus are in

the plane of, and very close to, the aortic valve

Once the measurements are complete, a very soft tipped,

fine torque wire is inserted into the catheter and the

stenotic aortic valve is probed with the catheter/wire

combination The technique is exactly as with any other

isolated retrograde approach to the aortic valve with the

exception that it is far more difficult from the umbilical

artery By the time the catheter/wire has been advanced

into the aortic root, the combination catheter/wire has

made two fairly acute and nearly 180° curves (passing

from the umbilical to the iliac artery and from the

des-cending to the asdes-cending aorta) As a consequence, torque

control and to-and-fro control over the catheter are

re-stricted markedly In addition, the “push” on the proximal

shaft of the catheter entering the umbilical artery must be

toward the groin and, counter-intuitively, “away” from the

direction of the aortic root Finally, there frequently is

significant arterial spasm along the course of the catheter,

which restricts catheter manipulation even further

If the wire can be manipulated across the valve and well

into the ventricle, and depending on which wire is used to

cross the valve, an attempt is made at passing the catheter

into the ventricle If the shaft of the original wire is

relat-ively soft, and depending upon the lumen diameter of the

dilation balloon catheter that is to be used, the initial wire

usually must be replaced with a wire which the dilation

balloon catheter can accommodate and which is stiffer in

order to support the delivery of a balloon/catheter

through the circuitous course Once the proper wire is in

place, the catheter that is over the wire is placed on a

con-tinuous flush through a wire back-bleed valve and the

appropriate balloon is prepared

When the dilation balloon is ready, the original catheter

is withdrawn over the wire leaving the wire positionedsecurely in the left ventricle The balloon dilation catheter

is advanced over the wire into the umbilical artery andthrough the circuitous course to the aortic valve This fre-quently cannot be accomplished or is only accomplishedwith one or more exchanges of wires When the bal-loon is positioned accurately across the valve, a rapidinflation/deflation is performed while recording the pro-cedure on biplane angiography or stored fluoroscopy.When the infant stabilizes after the balloon deflation,

if possible, the balloon is left in place across the valve until the angiograms of the inflation are reviewed Theinflation/deflation is repeated at least one more time Thereinflation/deflation verifies that the “waist” on the bal-loon does not reappear with the initial reinflation of theballoon If the infant does not stabilize rapidly after thedeflation with the balloon still across the valve, the bal-loon is withdrawn into the ascending (or descending!)aorta while simultaneously advancing the wire to main-

tain the wire’s position in the ventricleaif at all possible.

Once stabilized, an attempt is made at re-advancing thedilation balloon across the valve for at least one moreinflation/deflation

When the dilations have been completed, the balloon iswithdrawn over the wire, still leaving the wire in the ven-tricle The balloon catheter is replaced with an end-holecatheter, which is advanced over the wire into the ven-tricle If there is no prograde catheter in the left ventricle,the wire is withdrawn from the catheter, pressures arerecorded from the ventricle, and a biplane left ventricularangiogram is performed through this catheter Eventhough the retrograde umbilical catheter is an end-holecatheter, satisfactory left ventricular angiograms can beobtained through these catheters in a neonate A with-drawal pressure tracing from the left ventricle to theascending aorta is recorded, following which an aor-togram is performed in the aortic root to assess the move-ment of the valve leaflets and the degree of aorticregurgitation The catheter is removed and the umbilicalartery stump is oversewn When there is a progradevenous catheter positioned in the left ventricle during theprocedure, the pre- and post-left ventricular pressuresand any left ventricular angiograms are obtained throughthis catheter The prograde catheter obviates the necessity

of multiple recrossing of the valve with the umbilical/retrograde catheter

Because of the difficulties in maneuvering the catheters,wires and balloons from the umbilical artery approachand now with the much smaller balloon dilation cathetersthat can be introduced into the femoral arteries throughvery small (3- or 4-French) sheaths, the umbilical arteryapproach is no longer attempted in our center, although it

is still used as the preferred approach in some centers

Prograde approach to aortic valve dilation

There still are difficulties, particularly in smaller patients,

in using any arterial approach for aortic valve dilation

The various potential problems from the different arterial

approaches led to the development of techniques for the

venous approach for the prograde delivery of the dilation

balloon(s) to the aortic valve for aortic valve dilation The

usual prograde approach to the left heart is with catheters

introduced from the femoral veins, although the

umbil-ical veins have been used in neonates and the jugular/

brachial veins have been used in the presence of a

pre-existing interatrial communication These approaches

obviate virtually all of the particular problems with the

arteries that occur with the arterial approaches, but they

do have some significant difficulties of their own9,10

Prograde catheterization of the left ventricle and the

aorta through a pre-existing intracardiac communication

or by means of a transseptal atrial puncture are techniques

that are used very commonly The use of a diagnostic

catheter which is advanced prograde into the aorta after it

has been introduced into the left heart through a

trans-septal atrial puncture is part of the routine procedure for

dilation of the aortic valve in the older patient as described

earlier in this chapter When a prograde dilation of the

aortic valve is anticipated, two additional measures are

necessary First, when the transseptal puncture is

per-formed, the transseptal sheath (set) that is used must

be large enough in diameter to accommodate the largest

dilation balloon catheter that is to be used for the prograde

aortic valve dilation Secondly, the passage of the catheter

from the left atrium to the left ventricle initially is

accom-plished using a “floating” balloon catheter The inflated

balloon of a floating balloon catheter is more likely to float

preferentially through the true, central orifice of the mitral

valve, cleanly between the papillary muscles, and away

from any chordae This is essential in order to avoid the

eventual passage or expansion of the relatively large

dila-tion balloons through narrow channels in, or entangled

with, these valve structures

The hemodynamic data are recorded and angiography

performed in both the left ventricle and the aorta through

the prograde catheters as described earlier in this chapter

Once the hemodynamics and angiography are completed

and it is established that aortic valve dilation is indicated,

a long transseptal sheath is advanced over the floating

bal-loon catheter and positioned securely in the left ventricle as

near to the apex as possible If a double-balloon technique

is to be used, a second, appropriately sized, long

trans-septal sheath is introduced into the left atrium and the left

ventricle in a similar fashion to the first long sheath Either

an end-hole, floating balloon or torque-controlled catheter

is advanced through each long transseptal sheath As the

catheter tip reaches the tip of the sheath, the sheath is

withdrawn very slightly to allow the tip of the catheter

to exit the sheath without digging into the ventricularmyocardium The catheter(s) is(are) manipulated fromthe left ventricle, 180° into the aorta, around the arch and well into the descending aorta using the techniquesdescribed earlier The end-hole catheter used for this can

be either a soft, torque-controlled catheter or an end-hole,floating balloon Swan™ type catheter A floating ballooncatheter is usually easier and safer to use for this manipu-lation, although the smaller floating balloon catheters donot accommodate a 0.035″ guide wire

When the end-hole catheter(s) has/have been advancedwell into the descending aorta, an exchange length guide

wire is introduced into each catheter through a wire back

bleed valve With the catheter on a slow continuous flush,

the wire is advanced through the catheter and positionedsecurely in the descending aorta The exact wires useddepend a great deal on the size of the patient and the typeand size of balloons to be used Whenever possible, a relat-ively stiff wire is desirable in order to provide support forthe passage of a balloon catheter around the two 180°curves en route to the aortic valve and to hold the bal-loon(s) in place during the dilation At the same time, thewire cannot be so stiff that it holds the mitral valve openand that it “straightens” the normal 360° course from theright atrium to the aorta into a straight line! Occasionallythe stiff wire will not traverse around the curves throughthe original prograde catheter to the aorta or, even if thewire can be positioned in the aorta, it is so stiff that it holdsthe mitral and/or aortic valves open or “splints” the ven-tricular walls apart Any of these difficulties with the wireinterferes with the ventricular function to such a degreethat it cannot be left in place for even a few minutes Thewires in their course from the left atrium, through the ven-tricle, to the aorta must have a long loop, deep into the

apex of the left ventricle and must not pass across the

ven-tricular cavity The wires must be maintained in that tion throughout the dilation procedure in order to preventdamage to the mitral valve

posi-Once the appropriate wires are in satisfactory, stablepositions and the patient still remains stable, the catheter(s)remain(s) over the wire(s) while all of the catheter(s)and/or the long sheath(s) in the left ventricle are main-tained on a slow continuous flush while the dilation balloon(s) are prepared The dilation balloon for the pro-grade approach should be shorter than those used for aretrograde aortic valve dilation The shorter balloons facil-itate the delivery of the relatively stiff “balloon segment”

of the balloon dilation catheter through the tight curves

in the circuitous prograde course to a position across theaortic valve The shorter balloons also help to ensure that

the proximal ends of the balloons are positioned entirely in

the left ventricular outflow tract and well away from themitral apparatus when they are inflated After a balloon is

prepared, the original catheter is removed over the wire

while maintaining the wire in its position well into the

descending aorta and through the long sheath and, at the

same time, the tip of the sheath is maintained near the left

ventricular apex

Each balloon dilation catheter is introduced over the

wire into the long sheath in the femoral vein and

advanced to the aortic valve, all of the time maintaining

the sheath and the catheter lumen on a continuous flush

This circuitous route through two 180° curves within the

heart usually takes considerable and meticulous

manipu-lation of both the catheters and wires while maintaining

the sheath in position securely within the left ventricle

Care must be taken that the wire loops neither tighten nor

elongate excessively on themselves When the wires begin

to tighten, they pull against, and cut into, the valvular

structures and begin to pull the tips of the wires back out

of the aorta When the loops of wire elongate excessively

they “stent” the valvular structures open or cut into the

valves along the “outer circumference” of the loops The

long sheath maintained in position deep within the left

ventricular apex makes the balloon passage from the

left ventricle to the aorta slightly more difficult, but this

position of the sheath is essential to help prevent mitral

valve damage

When a wire repeatedly pulls back from the aorta

and cannot be maintained in the descending aorta as

the balloon dilation catheter is advanced over it, a snare

introduced retrograde is used to hold the wire in place A

Micro Vena™ snare catheter is introduced into a femoral

artery through a 4-French sheath The distal end of the

prograde wire in the descending aorta is grasped with a

10 mm Micro Vena™ snare introduced retrograde The

wire is held securely with the snare in this position,

which secures the distal end of the prograde wire in the

descending aorta Alternatively, the distal end of the

pro-grade, exchange length wire is withdrawn through the

descending aorta and “exteriorized” through the femoral

arterial sheath Either the snare catheter holding the

prograde wire or the exteriorized distal end of the wire is

secured on the table outside of the artery When a

pro-grade, double-balloon dilation is being performed, the

second wire also is grasped with a retrograde snare This

can be performed through the same femoral artery with

the same snare grasping the two wires simultaneously or

with a second snare through the opposite femoral artery

When a single snare catheter is used, unless the first wire

or both wires is/are “exteriorized”, the exact tension on

the separate wires cannot be controlled separately

If a retrograde sheath/catheter cannot be introduced

into a femoral artery for the snare catheter, or the

intro-duction is contraindicated, an attempt is made at

manipu-lating the prograde wire all the way around the arch, to

the descending aorta and into one of the femoral arteries,

advancing the tip of the wire to a position well beyond theinguinal ligament The prograde wire can often be fixed

in this position by firm, manual, finger pressure directlyover the artery, compressing the artery and, in turn, secur-ing the wire in the inguinal area This fixes the wire butdoes not allow any “counter traction” or other change inposition or tension on the wire from the distal end

The through and through control on the wire with theretrograde snare keeps the wire from being pulled out ofthe aorta and back into the left ventricle as the balloon isbeing advanced At the same time, the loops in the wirepassing through the heart with traction at both ends of thewire, can “tighten” the loops dangerously about the struc-tures in the heart For many reasons, significant tightening

of the wires must be avoided If the bare wires tighten,

they cut into the structures “within” the loopsain

particu-lar the medial leaflet of the mitral valve, the mitral dae, the left ventricular outflow tract and/or the aorticvalve itself As the loops of the wires tighten, the wires

chor-pull across the sub-valve apparatus of the mitral valve

If the wires remain across the sub-valve apparatus of the

valve as the balloon is advanced, the larger diameter,rougher surfaced, balloon also passes through or isexpanded in the sub-valve mitral apparatus causing dis-ruption of the apparatus The long sheath across the mitralvalve helps to protect the mitral valve but does not guar-antee that the mitral valve cannot be severely damaged.Even when the tightening loops do not cause injury, the

“tightening” and, therefore, narrower loops in the wire

create more resistance to the movement of the balloon

catheter over the entire course of the wire The tighter thecourse of the wire loops, the more difficult the passage ofthe balloon becomes The most extreme and dangerousdegree of “tightening” of the loops of the wire results inthe wire starting from its previous 360° course while pass-ing from the inferior vena cava, to the right atrium, leftatrium, left ventricle and out into the aorta, actually

straightening into an entirely straight course through the

same structures! This occurs with a sudden “flip” of thewire and unequivocally will damage intracardiac struc-tures This very dangerous phenomenon is prevented bythe continual observation of the course of the wires andnever allowing the “loops” in the wires to begin to tighten.The significant difficulties with the passage of a balloondilation catheter over the wire require an exchange of theoriginal wire for a smaller diameter wire or a wire withentirely different characteristics The prograde delivering

of the balloon on the balloon dilation catheter to the valve

is the most difficult part of this procedure

Once the balloon is positioned across the aortic valve,any wire loops or curves that were tightened excessively,are “loosened” by advancing the wire very carefully The

proximal end of the prograde balloon across the aortic

valve must be positioned cephalad in the left ventricular

outflow tract and away from the mitral valve apparatus A

long smooth loop of the wire is formed proximal to the

balloon in the left ventricular apex so that the wire will be

positioned well away from the mitral valve Initially the

balloon is inflated very slowly and only partially to be sure

that there are no unexpected or unwanted, additional

“waists” appearing from entrapment in part of the mitral

valve apparatus When the partial inflation appears

“clear” of abnormally located indentations, the balloon is

inflated and deflated rapidly as with any other aortic

valve dilation

In addition to the difficulty in delivering the balloon to

the aortic valve, there are some additional disadvantages

to the prograde technique for the dilation of the aortic

valve The smaller the patient or the smaller the heart, the

tighter the 180° curves or loops of wire/catheter become

and the more difficult it is to advance the balloons around

the multiple curves When the patient is

hemodynamic-ally unstable to begin with, all of the balloon/wire

manip-ulation is not tolerated These problems are compounded

in critically ill infants and particularly in small infants

with a relatively small left ventricular cavity where it is most

appealing to avoid the arterial approach If the patient

does not tolerate the balloon inflation or the balloon across

the valve per se, it is more difficult to withdraw the balloon

quickly from the valve and into a stable location than it is

from the retrograde approach In addition to the risk of

damage of the mitral valve and/or valve apparatus from

the wire/balloon catheter alone, and during the balloon

inflation, there also is a higher incidence of left bundle

branch block or complete heart block created during the

prograde procedure

Considering both the technical challenges and the

added risks of the prograde approach, the benefits of the

prograde approach for the dilation of the aortic valve must

be weighed heavily against the disadvantages before

embarking on this approach for aortic valve dilation

Complications of aortic valve dilation

The inability to complete an adequate dilation of the aortic

valve is not a “complication”, but is a failure of the

pro-cedure The failure of the procedure is not, in itself, an

adverse event for the patient unless there is an additional

separate complication from the procedure The

underly-ing disease and not the failure of the procedure itself,

cre-ates the necessity for further intervention At the same

time, complications specifically related to aortic valve

dilation are more common than with most, if not all, of the

other therapeutic catheter procedures

One of the most common complications specifically

associated with aortic valve dilation is injury to a

periph-eral artery Although the incidence of arterial injury has

decreased as a result of improvements in both the niques and in the available equipment for the procedure,arterial spasm, clots, tears and disruptions of the arterystill occur Prevention using meticulous technique and theuse of the least traumatic equipment possible preventsmost arterial injuries (Chapter 4) Early recognition of

tech-an arterial problem with early intervention ctech-an preventpermanent sequelae The availability and use of specificcatheter interventions and of more effective thrombolyticsfor arterial thrombi are discussed in Chapters 2 & 35 It

is now extremely rare for a patient to require a surgicalarterial repair or have any permanent sequelae as a consequence of a retrograde arterial procedure even in

a small infant

The most serious complications from aortic valve tions are injuries to the central nervous system As withany procedure on the “systemic side” of the circulation,the potential for embolic events to systemic organs, par-ticularly the head, is always present during aortic valve dilations There are innumerable opportunities for theintroduction of air and/or clots into the circulation prox-imal to the head vessels during the multiple manipula-tions in the aortic root, left ventricle, and left atrium Airembolization absolutely should be preventable by the use

dila-of meticulous technique

Solid particle embolization is a different story Thrombieasily form on guide wires, on and within catheters and sheaths and specifically on balloon dilation catheterswithin the folds of collapsed balloons Patients undergo-ing these procedures are always anticoagulated with hep-arin during the procedure Unfortunately, even this is notsufficient to prevent thrombus formation unequivocally.The best that can be done to prevent thrombi is to keep thepatient’s ACT level above 300 seconds, to be as expedient

as possible with manipulations in the systemic circulation,and to keep all catheters and wires through catheters on

a continuous flush “Parking” catheters and, particularly,balloon catheters in the descending aorta as opposed tothe ascending aorta when they are not being used forrecordings/procedures specifically in the aortic root,reduces the likelihood of a “head” event

The most unpredictable, frustrating and probably, themost common complication of aortic valve dilation is

the creation of significant aortic valve regurgitation It is

the most frustrating complication because the specificcause of the regurgitation in any one patient is still not

known although it is a potential risk, as a consequence of

every balloon dilation of the aortic valve Significant aortic

regurgitation occurs in approximately 10% of all balloondilations of the aortic valve This number is comparable

to its occurrence following surgical aortic valvotomy, but whether it is a problem in the same patients whetherthey undergo surgery or catheterization is not known Itappears that over-sizing of the balloon for the aortic valve

annulus is one predictor for the creation of aortic

regurgi-tation, however aortic regurgitation certainly is created

even when using a precisely measured balloon to annulus

ratio of less than one Unquestionably, the wire and then

the balloon passage through a valve leaflet rather than

through the commissures/orifice of the valve results in

significant regurgitation This problem may not be

recog-nized until after the fact This particular cause of

regurgi-tation is avoided by gentle retrograde probing of the valve

with very soft, floppy tipped wires and by directing the

retrograde wire along the precise course of a previously

positioned catheter that is passing prograde through the

valve orifice.

Once even a moderate amount of aortic regurgitation

is created during a balloon dilation procedure, no further

dilation of the aortic valve is attempted regardless of

the residual obstruction Fortunately, patients with very

significant aortic stenosis and, particularly, those with

significant chronic aortic stenosis tolerate even moderate

to severe degrees of acutely created aortic regurgitation

without the immediate need for valve repair or

replace-ment Massive aortic regurgitation with acute left

ventric-ular decompensation does occur, particventric-ularly in patients

who have only moderate aortic stenosis with no

ventricu-lar hypertrophy before the dilation, and whose ventricles

are “unprepared” for the sudden volume load This is the

major contraindication to dilation of mild or moderately

severe aortic valve stenosis Facilities must be available

for urgent surgery and acute valve replacement in the case

of such an occurrence in any patient undergoing aortic

valve dilation

Mitral valve damage during the prograde approach

for aortic valve dilation has been discussed previously

Avoiding the prograde approach for dilation of the aortic

valve is the best method of preventing this complication

However, the mitral valve apparatus can be disrupted

even during a retrograde dilation of the aortic valve It is

possible for the retrograde wire and then the balloon to

pass through and become entrapped in the mitral valve

chordae If this is not recognized, the mitral valve can be

damaged An indicator of this potential problem is a very

posterior and “less mobile” position of the retrograde wire/

balloon in the ventricle A left ventricular

angiocardio-gram or a transesophageal echocardioangiocardio-gram demonstrates

the errant wire/balloon position in the mitral apparatus

Perforation of the left ventricle is possible during

dila-tion of the aortic valve A straight wire, particularly with

a shorter, straight “floppy” tip is more likely to perforate

the myocardium as it is extruded out of the tip of a

catheter, although even a wire with a long floppy tip can

perforate if enough forward force is placed on the wire

when the tip of the catheter is “buried” in the myocardium

and cannot bow or bend away from the tip of the catheter

If there is a very sharp kink or angle on the stiff portion of

the wire when a “curve” on the stiff or transition zone ofthe wire is positioned in the apex of the left ventricle

and the balloon “milks” into the ventricle during inflation,

the balloon pushes the acute, sharp angle on the wire

fur-ther into the ventricle A straight wire with no curve on the

transition zone can kink acutely and be driven throughthe ventricular wall by a rapid forward force on the wirecaused by a “squirting” balloon This is true particularlywith small sick infants

A problem that is more likely to occur in, but is nottotally limited to, sicker patients is the inability of theheart to recover and the patient to stabilize after the totalobstruction of cardiac output by the balloon inflation/deflation in the aortic valve Usually, the relief of theobstruction by the dilation is sufficient to allow the rapidreturn of the heart rate, blood pressure and, in turn, a bet-ter cardiac output with rapid stabilization of the patientimmediately after the balloon(s) is/are deflated On rareoccasions, the myocardium initially is so damaged and is

“stunned” even further by the acute and total obstruction

of coronary flow during the balloon inflation that whenthe balloon is deflated, there is no return of cardiac func-tion in spite of all resuscitative efforts This may not beentirely preventable It is less likely to happen if the patientwas pretreated adequately and heart failure, shock andacidosis were corrected before the dilation procedure The double-balloon technique allows some forward flowthrough the valve when the balloons are at full inflation,which reduces the adverse heart rate and blood pressureeffects

The so-called “hooded coronary” orifice can result in acatastrophic outcome in association with balloon dilation

of the aortic valve With this lesion the orifice of a coronaryartery lies low or deep in the coronary sinus While thevalve is stenotic, the “tethering” or doming of the leafletsholds the leaflets away from the abnormally locatedorifice, but when the valve is dilated successfully, particu-larly if one leaflet becomes partially flail, the leaflet thenfolds completely against the wall of the sinus and, in turn,over the orifice of the coronary artery, acutely obstructingflow into the coronary The best indicator of this abnor-mality is a very low position of the coronary orifice andthe closeness of the aortic leaflet to the coronary orificebefore the valve undergoes dilation Recognition andimmediate surgical intervention are the only managementfor this rare abnormality

Rupture of the aortic valve annulus is another trophic event that can occur during aortic valve dilation,but probably is preventable This complication is unlikely

catas-to occur unless the balloon(s) is/are oversized markedlyfor the annulus size or the patient has underlying aortic wall disease such as the medial necrosis as seen inMarfan’s syndrome As a consequence, this problem theoretically should be avoidable by meticulous attention

to the measurements of the annulus, using valid reference

calibration measurements, and by thorough knowledge of

the patient’s history

In spite of the numerous potentially serious

complica-tions of balloon dilation of the aortic valve, the benefits of

dilation of the aortic valve still outweigh the risks of the

catheter procedure and the risks of the alternative

man-agement/therapy as long as meticulous attention is given

to the details of the performance of the procedure

References

1 Lababidi Z, Wu JR, and Walls TJ Percutaneous balloon aortic

valvuloplasty results in 23 patients Am J Cardiol 1984; 53:

194–197.

2 Rocchini AP et al Balloon aortic valvuloplasty: Results of the

Valvuloplasty and Angioplasty of Congenital Anomalies

Registry Am J Cardiol 1990; 65: 784–789.

3 Justo RN et al Aortic valve regurgitation after surgical versus

percutaneous balloon valvotomy for congenital aortic valve

stenosis Am J Cardiol 1996; 77(15): 1332–1338.

4 Zeevi B et al Neonatal critical valvar aortic stenosis A parison of surgical and balloon dilation therapy Circulation

com-1989; 80(4): 831–839.

5 Mullins CE et al Double balloon technique for dilation of

valvular or vessel stenosis in congenital and acquired heart

disease J Am Coll Cardiol 1987; 10(1): 107–114.

6 Fischer DR et al Carotid artery approach for balloon dilation

of aortic valve stenosis in the neonate: a preliminary report

9 Magee AG et al Balloon dilation of severe aortic stenosis

in the neonate: comparison of anterograde and retrograde

catheter approaches J Am Coll Cardiol 1997; 30(4): 1061–

In the more developed countries of the world, mitral

stenosis in children is predominately congenital in origin

and, fortunately, is a relatively rare abnormality1 The

stenosis in the congenitally malformed mitral valve has

multiple variations and involves all parts of the mitral

valve apparatus The “characteristic” congenital mitral

stenosis has a single papillary muscle, the valve leaflets

are fused into a funnel-like or “parachute” deformity, and

there are no real commissures of the valve The leaflets

alone can be fused without the fusion of the papillary

muscles or vice versa There also often is a “supra-valve”

obstructive membrane within the left atrium just above

the mitral valve annulus with or without the other

abnor-malities of the mitral valve apparatus In spite of the

com-plexity of these lesions, some of these valves are amenable

to balloon dilation2,3

The success of either balloon dilation or reconstructive

surgery for congenital mitral valve stenosis depends a

great deal upon the initial anatomy of the stenosis A

suc-cessful balloon or surgical dilation opens the stenosis and

relieves the obstruction, but still only represents

palliat-ive therapy This palliation hopefully delays the almost

inevitable mitral valve replacement Dilation of

congeni-tal mitral valve stenosis by any technique is likely to

pro-duce some mitral regurgitation Fortunately, the degree of

insufficiency usually is not great, is tolerated moderately

well and certainly is tolerated better than a very tight

stenosis Because of the relative difficulty and the risks

and the lack of predictability of the results of dilation

of congenital mitral stenosis, the criteria for performing

balloon dilation of congenital mitral stenosis are more

stringent than for most other therapeutic procedures in

the congenital cardiac catheterization laboratory Even

moderate mitral stenosis symptomatically is tolerated

quite well and the presence of the stenosis per se is not

an indication for intervention Patients with congenital

mitral stenosis are considered for intervention only whensymptoms become significant or when secondary pul-monary hypertension develops When balloon dilation

of a congenital mitral valve stenosis is anticipated, thedefinite possibility of creating significant mitral regurgita-tion, which will require a mitral valve replacement, mustalways be included in the decision for and the discussionsabout the balloon valvotomy

In the developing countries of the world where acuterheumatic fever is still rampant, rheumatic mitral valvestenosis is very common and does occur in young children.Because the rheumatic stenosis represents the fusion of whatwere previously normal, bicuspid, mitral valve leaflets,the dilation of the acquired fusion is far more successfulthan the dilation of the congenitally deformed valves As aconsequence, the indications for catheter intervention forrheumatic mitral stenosis are much more lenient than forthe congenital mitral lesions The presence of rheumaticmitral stenosis with any symptoms or with even the sug-gestion of an increase in right ventricular and pulmonaryartery pressures is an indication for intervention for rheu-matic mitral stenosis in children, adolescents and adults4.Balloon dilation is considered the standard primarytherapy of rheumatic mitral stenosis at virtually any age,however, in the older patient with mitral stenosis, the deci-sion for valve dilation is weighed against the amount ofacquired degenerative changes in the valve5 In the child

or adolescent with rheumatic mitral stenosis, the ative changes in the valve that produce the contraindications

degener-to balloon therapy are usually not present In the youngerage group the mitral valve stenosis must be distinguishedfrom congenital mitral stenosis, which may represent acontraindication to balloon dilation of the valve

The applicability of a stenotic rheumatic mitral valve for

a transcatheter mitral valvuloplasty is determined on thebasis of a combined echocardiographic and X-ray gradingsystem The thickness of the leaflets, the restriction in the valve motion, the sub-valvular thickening due to thefusion of the chordae or the papillary muscles and the

20

amount of calcium in the valve on X-ray are all

determin-ates in the “mitral valve score” Each of these factors is

graded 1 through 4 according to the worsening degree

of severity, and when the numerical grades are added

together, give the “score” The higher the score, the less

likely the procedure is to succeed and the greater the

chances of complications6 Thrombi or masses within

the left atrium are relative contraindications to balloon

dilation of the valve regardless of the other findings

The balloon types and sizes used for mitral valve

dila-tion vary according to the size of the mitral valve annulus,

whether the dilation is with a single “standard” balloon, a

double-balloon technique or with the Inoue™ balloon

The dilation technique and type of balloon(s) used are

mostly chosen according to the preference of the

particu-lar operator and the availability of the particuparticu-lar

neces-sary equipment in the catheterization laboratory There is

a great variability in how the mitral annulus diameter is

measured and, in turn, how the balloon sizes are

deter-mined for balloon dilation of the mitral valve The mitral

annulus is not actually measured in some adult series, but,

instead, the balloon diameter is chosen arbitrarily

accord-ing to the patient’s body size Other series utilize a

for-mula or a graph according to the patient’s measured

height and/or body surface area to “calculate” the balloon

size to be used

The size of the Inoue™ balloon is frequently

deter-mined according to the patient’s height using the formula:

Inoue™ balloon size = patient’s height (in cms) ÷ 10 + 10

This diameter is the maximum diameter of the

particu-lar balloon With the variability in the diameter of the

Inoue™ balloon possible during the dilation, this allows

the operator to begin the dilation using a diameter 4 mm

smaller than the maximum for that balloon and then

sequentially increasing the diameter up to the calculated

end or maximal diameter of that balloon, all without

hav-ing to exchange balloons

For the double-balloon techniques it is better to

meas-ure the various diameters of the mitral valve annulus

angiographically using several angled views or by

echo-cardiography in several different planes When actually

measured, the dimension of the mitral annulus in the

lat-eral projection usually is 25–30% longer than the posterior–

anterior dimension The longest annulus diameter is used

in choosing the two balloons The combined diameter

of the two balloons used is usually equal to, or up to, 1.3

times the longest measured diameter of the mitral

annu-lus Occasionally, when there is very gross malformation

of a congenitally stenotic mitral valve, the balloon dilation

is started with smaller diameter balloons If the annulus

diameter is not adequately measured by either modality,

then a graph of normal valve diameters according to body

surface area is used to determine the balloon sizes7

Techniques for balloon dilation of the mitral valve

With the exception of one of several retrograde proaches for balloon dilation of the mitral valve and theextremely rare incidence of either transhepatic or trans-

ap-jugular access to the atrial septum, most balloon dilation

procedures of the mitral valve are performed from thefemoral venous approach The usual, as well as the alter-native approaches, to transcatheter dilation of the mitralvalve are discussed in this chapter

The mitral valve can be dilated using a single, large,

“standard” angioplasty balloon, with one of several ferent double-balloon techniques or, in larger patients,dilation with the Inoue Balloon™, which is designed spe-cially for mitral valve dilation All of these procedureshave advantages and disadvantages Each procedure hasits advocates The double-puncture, double-balloon tech-nique and the Inoue Balloon™ procedure are discussed

dif-in detail The sdif-ingle-balloon technique usdif-ing a large

“standard” balloon and the double-balloon using a singletransseptal puncture are mentioned only in comparison tothe other two, more preferred techniques

The safest technique (and the standard of care in oped countries) is to use biplane fluoroscopic guidance forcontrol of the transseptal procedure(s) as well as the actualmitral valve dilation procedure The actual dilation of thevalve also is supported with echocardiographic guidancecontrol Transthoracic echo (TTE) can be used particularly

devel-in the smaller patient, but now the trend is to use esophageal echo (TEE) or intracardiac echo (ICE) for guid-ance of the procedure In addition to the more reliableimages of the valve, both TEE and ICE have the advantagethat the transducer and the echocardiographer’s handsare out of the fluoroscopy field during the dilation pro-cedure The TEE procedure has the disadvantage that itrequires general anesthesia for most patients to toleratethe TEE probe, and at the same time to hold still for theduration of the procedure The experience with ICE is still

trans-limited, and it still requires the presence of an additional

large venous sheath

The catheterization and dilation of the mitral valve can

be performed with deep sedation and local anesthesia

when transesophageal echocardiography is not used to

guide the procedure If transesophageal graphic monitoring is used during the dilation procedure,then general anesthesia is used for the whole procedure

echocardio-Double-balloon, double transseptal puncture technique

A separate venous sheath is introduced percutaneouslyinto both the right and left femoral veins, and a small

indwelling arterial cannula placed percutaneously into

one femoral artery As mentioned in the description of

the transseptal technique in Chapter 8, it is imperative that

the catheter course from the femoral puncture passes

through the true femoral vein and not through pelvic

col-lateral veins, which pass deep into the posterior pelvic

and perirectal venous system Right heart pressures and

cardiac output determinations are obtained with a right

heart catheterization Pulmonary artery and pulmonary

arterial wedge pressures obtained during this part of the

procedure help to substantiate the severity of the mitral

stenosis Following the acquisition of the “right heart” data,

the transseptal left heart catheterization is performed

When the double-balloon, double transseptal technique is

used, separate transseptal punctures are performed with

an approach from both inguinal areas The exact severity

of the stenosis and the anatomy of the valve and valve

apparatus are determined after the left heart is entered

transseptally

A double-balloon technique through two separate

transseptal punctures introduced from separate groins

is preferred for children as well as for smaller adults

This allows the introduction of two smaller balloons

into smaller peripheral veins and the passage across

the intra-atrial septum through two smaller and widely

separated holes in the atrial septum With the current

bal-loon technology, both balbal-loon catheters are introduced

through long sheaths The two punctures in the atrial

sep-tum are separated from each other by at least a centimeter

to prevent the two openings from coalescing and creating

one large and permanent hole in the septum! In a large

patient with a large mitral annulus, the double-balloon

technique allows the use of two balloons of adequate

combined diameter without the necessity of using one

very large, very bulky, and irregular, single, mitral

“angio-plasty” balloon with its very rough and traumatic deflated

profile

The two transseptal punctures are performed from

catheters introduced from the separate right and left

femoral veins (The transseptal technique is described in

detail in Chapter 8.) In the adult and in the moderate, or

large sized child or adolescent, both transseptal sheath/

dilator sets can be introduced through separate punctures

into the same femoral vein in either inguinal area when

there is an access problem from one side When using

bilateral femoral veins, it is preferable to perform the first

transseptal puncture with the catheter that is introduced

into the left groin The transseptal procedure from the left

groin usually requires bending the patient’s thorax to the

right in order for the needle to align more perpendicular

to the septum and to engage or impinge on the septum

during the actual puncture Performing the first

punc-ture from the left femoral vein allows freer bending

and movement of the patient during the first transseptal

puncture without fear of dislodging a previously tioned transseptal sheath by the movement of the patientduring the second puncture

posi-Although certainly not essential (or maybe even able!), the use of TEE guidance is popular for needle guid-ance during the transseptal puncture It is complementary

desir-to the fluoroscopy, but should not replace the use of biplane

fluoroscopy as the primary means of visualizing the tures Once the tip of the needle and the transseptal set isimpinged on the septum, TEE, then, is helpful for localiz-ing the site of the puncture on the septal surface and helps

punc-to ensure that the two puncture sites are separated fromeach other by at least a centimeter The TEE image of theneedle on the septum also provides a security check inavoiding the aortic root and the atrial septum–posteriorwall junction during the puncture, particularly whenthere is a small left atrium

When the right heart catheterization is performed fromthe left inguinal area or if sheaths are in both femoral

veins, the left venous catheter and sheath are replaced

over a wire with a 7- or 8-French transseptal set Thetransseptal set has a sheath with a back-bleed valve with aflush port and a radio-opaque marker band at the distaltip of the sheath The transseptal set is advanced over thewire into the superior vena cava and, preferably, into the left innominate vein The wire is withdrawn from thetransseptal set, the dilator cleared of air and flushed, the transseptal needle is introduced into the dilator,

advanced to just within the tip of the dilator and then

attached to the pressure/flush system The patient’s rax is angled (bent, not twisted!) to the patient’s right Thisbending creates a more perpendicular angle between thetip of the transseptal needle and the atrial septum once thetip of the needle has been withdrawn into the right atrium.With the pressure from the needle displayed on a 20 or

tho-40 mmHg scale, the sheath/dilator/needle is withdrawn/rotated from the superior vena cava and along the rightatrial surface of the interatrial septum, as described indetail in Chapter 8 (“Transseptal Technique”)

The transseptal puncture is performed as low on theatrial septum as is possible For these low positions for

puncture through the septum, TEE is useful to ensure that

the needle tip and, in turn, the puncture is not originatingfrom within the coronary sinus After the needle tip passesthrough the septum into the left atrium, visualization of

the posterior wall of the left atrium by TEE helps, but usually

is unnecessary, in avoiding puncture through the ior wall into the pericardium While observing pressurecontinuously through the needle, the needle/dilator/sheath are advanced through the septum and into the left

poster-atrium until the tip of the sheath is well within the poster-atrium.

With any loss of pressure, advancing the needle/longsheath/dilator is stopped, the tip of the needle is rotatedhorizontally slightly and the location of the needle tip is

determined precisely with a small injection of contrast

through the needle

Once the tip of the sheath is well into the left atrium, the

needle first and then, separately, the dilator are removed

slowly from the sheath The dilator is allowed to bleed

back and drip fluid/blood out of the end of its hub as it is

withdrawn The sheath is then cleared meticulously of

any air and clots by allowing passive free flow of blood out

of the side arm of the back-bleed device while tapping and

rotating the back-bleed valve chamber The long sheath

in the left atrium along with the wire/dilator/catheter

exchanges through the sheath positioned in the left heart

represent the greatest potential hazards of the procedure

The wire/catheter manipulations through the long sheath

with the sheath tip positioned within the left atrium create

a huge potential for the introduction of air or clot into the

left heart Meticulous attention must be taken in clearing

the sheath to avoid this Once the sheath, including the

hub/chamber of its back-bleed valve, unequivocally is

cleared of any air or clot, the side arm of the sheath is

attached to the pressure/flush system At this point in the

procedure the patient is given 100 mg/kg of heparin

intra-venously through the long sheath When pressures are not

being recorded through the sheath, the sheath is

main-tained on a slow flush of heparinized flush solution

Once the first transseptal sheath has been secured in the

left atrium, the hemodynamics and anatomy of the mitral

stenosis are confirmed An accurate left atrial pressure is

recorded through the side arm of the sheath or through

a catheter introduced through the sheath into the left

atrium When the catheter is at least one French size

smaller than the sheath, pressures can be recorded

through both the catheter and the sheath simultaneously

The two simultaneous pressures from the left atrium

serve as an extremely reliable method of documenting the

accuracy of the two transducers (Chapter 10) The two

pressure tracings should produce a single line on the

mon-itoring screen Once the pressure in the left atrium is

recorded, angiocardiograms can be performed in the left

atrium to define the valve anatomically and to localize

various left heart structures An angiographic catheter is

advanced into the left atrium through the long sheath In

order to obtain the most useful anatomic information

about the valve, the X-ray tubes are positioned at angles

that are as perpendicular to the annulus of the valve as

possible The mitral valve usually is “cut on edge” with a

right anterior oblique/caudal (RAO/caudal) angulation of

the posterior–anterior (PA) X-ray tube A very steep left

anterior oblique/cranial (LAO/cranial or “four

cham-bered”) angulation of the lateral tube provides the closest

to perpendicular view of the valve from the lateral X-ray

plane However, it often is impossible to obtain a steep

enough cranial angulation with the lateral X-ray system to

cut the valve absolutely “on edge” from the LAO/cranial

angle Even though the entire valve may not be “on edge”with the LAO/cranial view, this view does give a seconddimension for measurement of the diameter of the valve

annulus and the sub-valve apparatus Since no two

patients and valves are the same, frequently several leftatrial angiocardiograms with changes in the X-ray tubeangulations are needed to position the mitral valve optim-ally “on edge”

From the left atrial angiocardiograms, the exact size,anatomy and position of the orifice of the mitral valve aredetermined During the angiocardiograms, either a cali-brated marker catheter, some type of external referencegrid, or large diameter calibration system built into the X-

ray system is used in each plane of the angiocardiograms

for accurate measurements of the valve annulus The urements should be recorded in as many views as pos-sible including specifically where the valve attachmentsare visualized within the ventricle The maximum meas-ured diameter of the valve annulus is used to determine the combined balloon diameters for the dilation TEE/ICE

meas-is used along with the angiocardiogram to define thevalvular anatomy and for a corroborative measurement ofthe annulus

A frame of the angiocardiogram from both planes of theX-ray is placed in a “freeze frame” image to be used as a

“road map” during the dilation If quality “freeze frame”

or image storage capabilities are not available, an externalradio-opaque marker can be placed on the skin surfacecorresponding to the location of the valve as visualized onthe angiogram This marker is used to identify the level ofthe valve orifice during the dilation A lead shot (#5!) or alead number 1 from a radiographic film “labeling set”,taped onto the chest wall in both planes, serves as anexcellent reference marker

With the left atrial pressure recorded and the mitralanatomy defined and measured accurately angiographi-cally, an angiographic catheter at least one French sizesmaller than the long transseptal sheath is manipulatedfrom the left atrium into the left ventricle With the angio-graphic catheter positioned in a stable location in the leftventricle and the tip of the larger French sized sheath still

within the left atrium, very accurate, simultaneous

pres-sure tracings of the left atrial and left ventricular prespres-suresare recorded from the side arm of the sheath and thecatheter, respectively These pressures provide the exactgradient across the stenotic mitral valve The valve areacan be calculated using this gradient along with the car-diac output determinations obtained during the rightheart catheterization

Once accurate and simultaneous left atrial and left ricular pressures are recorded, the X-ray tubes again arepositioned into the angles that are the most perpendicular

vent-to the valve annulus and a biplane left ventricular diogram is performed Often the negative shadow of the

angiocar-mitral valve in a densely opacified left ventricular image

gives more information about the exact location of the

opening, size and excursion of the mitral valve leaflets

than the left atrial angiocardiogram If so, a frame of the

left ventricular angiocardiogram in the exact position

that will be utilized during the valve dilation procedure

is stored on the “freeze frame” to serve as a reference for

positioning the dilating balloons once they are exactly

within the lesion

After accurate measurements have been made of the

mitral annulus, the balloons are chosen for the dilation

The combined balloon diameters should be equal to or

1.2–1.3 times greater than the measured largest diameter

of the mitral valve annulus Relatively long balloons

are used, but, at the same time, balloons with short

“shoulders” and short tips are necessary Some balloons

are available with a “pig-tail” curve at the tip rather than

a short stubby tip The “pig-tail” is designed to keep the

balloon tip from driving into or through the ventricular

wall if the balloon is displaced into the ventricle during

inflation The longer balloons are necessary to span the

entire “depth” of the mitral valve and the valve apparatus,

and to help keep the dilating surface of the balloons from

moving in and out of the valve during the inflation

Once the angiocardiograms are completed, the

meas-urements obtained, and the size of the balloons chosen,

the angiographic catheter is withdrawn from the left

ven-tricle and from the body through the sheath Preparations

are made for the second transseptal puncture The two

balloons will be delivered through the septum through

two separate long transseptal sheaths If a larger sized

sheath than the one already in the left atrium is necessary

to accommodate one or both of the balloons that are to

be used for the dilation, the initial transseptal sheath is

exchanged for the appropriate larger sized sheath/dilator

at this time The exchange is made over a wire passed

through the first sheath into the left atrium or

pulmon-ary vein Once the new, larger sheath is secure in the left

atrium, the second transseptal puncture from the opposite

femoral vein is carried out using a second larger

trans-septal sheath/dilator set that will accommodate the

dilation balloon

The exact location on the septum of the second puncture

will depend upon where on the septum the earlier

punc-ture was made The second puncpunc-ture should be at least a

centimeter away from the first puncture and can be above,

below, in front or behind the first punctureawherever

there is the most room and distance from the first

punc-ture The location of the second puncture on the septum in

relation to the first puncture site and the rest of the septum

is identified from the earlier left atrial angiograms and by

TEE/ICE interrogation The second transseptal puncture

is carried out identically to the first transseptal procedure

except that when approaching from the right inguinal

area, the patient’s body usually does not have to be bent toalign the septum better

After both transseptal sheaths are secured in the leftatrium and cleared of air/clot, the side arms of bothsheaths are attached to the pressure/flush system andplaced on a slow continuous flush When the two longsheaths are placed on their separate pressure recordings,the two simultaneous pressures from the left atrium againserve to document the accuracy of the two transducersand, in turn, the reliability of the previous hemodynamics

The two pressure tracings should produce a single line on

the screen

In order to position the guide wires across the mitralvalve for the dilation, an end-hole catheter is advancedthrough one of the sheaths that are positioned in the leftatrium, and maneuvered through the mitral valve andinto the left ventricle It is safer, usually easier and alwaysbetter to “float” an end-hole, floating balloon catheterthrough the mitral valve than to maneuver a standardend-hole catheter from the left atrium to the left ventricle.The inflated balloon has a better chance of passingthrough the “center” and/or the largest orifice of themitral valve apparatus and not through a narrow slit in aleaflet and/or fused chordae of the valve TEE/ICE, aswell, is very helpful in determining the exact course of thecatheter through the valve apparatus

When the opening in the mitral orifice tolerates it, thesheath is advanced over the catheter and into the left ven-tricle Once the sheath and the end-hole catheter are in theleft ventricle and well past the mitral valve apparatus, thetip of the catheter is advanced out of the sheath andmaneuvered toward the left ventricular outflow tract Theexact mechanism of this maneuver depends upon the sta-bility of the patient, the type of catheter in the left ventricleand the preference of the operator The sheath over thecatheter and through the mitral valve into the left vent-ricle helps to support the more proximal shaft of a floatingballoon catheter in this maneuver As the balloon catheter

is pushed forward through the sheath, the sheath holdsthe shaft of the catheter in the left ventricle and keeps

it from backing up while the tip of the balloon cathetergenerally is forced to turn or deflect cephalad more or less,toward the LV outflow tract

When the long sheath cannot be maintained across themitral valve or the tip of the balloon catheter does notdeflect toward the outflow tract on its own in the small leftventricular cavity, a controllable deflector wire is used todeflect the catheter tip toward the outflow tract The activedeflector wire also provides an effective technique for deflecting a standard, “non-floating” end-hole catheter or

a floating balloon catheter that is not passing through asheath, toward the outflow tract The deflector wire, orany other wire introduced through the catheters in the

left heart, are introduced into the catheters through a wire

back-bleed valve and the catheters are maintained on a slow

continuous flush around the wire The tip of the catheter

in the apex of the left ventricle is deflected into a 180°

curve with the deflector wire The catheter is advanced off

the wire toward, and well into, the left ventricular outflow

tract (LVOT) or even out through the aortic valve If the

catheter tip deflects in the direction of the aortic valve, but

the catheter cannot be advanced into the outflow tract,

the deflector wire is removed and replaced with a

torque-controlled, exchange length, guide wire with a slightly

curved, very floppy tip While keeping the catheter tip

directed toward the outflow tract, the curved floppy tipped

wire is passed through the catheter and maneuvered

out of the catheter and into the ascending aorta using

the torque mechanism on the wire to direct the tip Once

the wire has been secured in the aorta, the catheter is

advanced over the wire

In a small patient or in a patient with a small left

ventricu-lar cavity, the catheter passage into the left ventricuventricu-lar

outflow tract/aorta often cannot be accomplished with

a catheter large enough to accommodate the larger Super

Stiff™ wire (Boston Scientific, Natick, MA) that is to

be used for the balloon dilation of the mitral valve In that

circumstance, the deflection into the outflow tract is

per-formed with a smaller catheter, using a smaller deflector

wire, and then is exchanged for a smaller diameter

exchange length wire The smaller exchange length wire,

however, will not support the balloon dilation catheters

adequately for the dilation procedure The smaller gauge

wire is advanced through the smaller catheter and into the

aorta Once the smaller exchange wire is well into the

aorta, the original catheter is withdrawn over the smaller

exchange wire and replaced with a 6- or 7-French,

end-hole, either woven dacron, extruded polyethylene, or

even a Toray™ “Glide” catheter These catheters are large

enough to accommodate a 0.035″ wire, but at the same

time are malleable enough to follow the smaller wire into

the aorta These larger catheters positioned in the aorta

are rigid enough to guide a larger, pre-curved, Super

Stiff™ wire through the circuitous route from the venous

entry site to the apex of the left ventricle Once the larger

catheter has been advanced over the smaller gauge,

exchange length wire and into the ascending aorta, the

smaller wire is withdrawn, the catheter cleared of all

debris and placed on a slow continuous flush through a

wire back-bleed/flush port

Alternatively, a 6- or 7-French “pig-tail” catheter can be

used to position the larger Super Stiff™ wire in the left

ventricle The “pig-tail” catheter is introduced into the

left atrium directly through the long sheath and then

deflected from the left atrium into the left ventricle The

loop of the “pig-tail” passing through the mitral apparatus

has the same effect as a floating balloon catheter, as the

diameter of the “loop” of the “pig-tail” “backing” through

the valve obligates the catheter to pass through the largest

orifice of the stenotic mitral valve If a small exchange wire

already had been introduced into the aorta or left lar outflow tract, the pig-tail catheter is advanced over thesmaller wire, through the long sheath and into the leftatrium The pig-tail catheter is advanced through themitral valve and the curved tip or “loop” is pushed into

ventricu-the apex of ventricu-the left ventricle When ventricu-the pig-tail is passed

over the small wire, once the curve of the pig-tail is fixed

in the apex, the smaller wire is withdrawn completelyfrom the catheter The pig-tail curve seated in the left ventricular apex will usually deflect the long tip of a SuperStiff™ wire 180° when it is advanced into, and through,the loop and, in turn, directs the floppy tip of the wiretoward the left ventricular outflow tract This allows thetransition zone and curved stiffer portion of the wire to

“seat” in the apex of the ventricle

Once the first larger end-hole catheter is positionedsecurely across the mitral valve with the tip directed intothe LVOT, the procedure is repeated through the secondlong transseptal sheath The second long transseptalsheath already is positioned in the left atrium The mitralvalve is crossed with a second floating balloon catheterpassed through the second long sheath The catheter ismaneuvered into the LVOT or aorta using a techniquesimilar to that used for the first catheter as described

above The patient usually tolerates the two catheters

across the mitral valve and into the LVOT better than evenone of the Super Stiff™ wires within those catheters acrossthe valve

With the prograde catheters in place and ready for theinsertion of the Super Stiff™ wires, the indwelling femoralartery line is replaced with a small arterial sheath Anangiographic catheter is introduced through the femoralartery sheath and advanced retrograde into the left vent-ricle This retrograde catheter in the left ventricle was not

an absolutely essential part of the procedure up to thispoint, but during the rest of the procedure, the retrogradecatheter facilitates the assessment of the results of the balloon dilation immediately after the mitral dilationwithout the need for removing or exchanging either balloons or wires

Once all of the catheters are in place, two Super Stiff™ exchange length wires with long floppy tips (7 cm)

(Boston Scientific, Natick, MA) are pre-shaped specifically

for the mitral dilation and specifically for the particularpatient The wires used must be able to pass through theballoon dilation catheters that have been chosen for thedilation An exchange length, teflon-coated, 0.035″ Super

Stiff™ wire with a long floppy tip is used to support each of

the balloons during a double-balloon mitral valve tion Preferably, the long floppy tip should have a tight “J”

dila-or “pig-tail” curve fdila-ormed at the very end of the floppytip If only straight, long, floppy tipped Super Stiff™ wires

are available, a J or tight pig-tail curve is formed on the

entire floppy portion of the wire The J or pig-tail curve at

the tip of the wire keeps the wire from digging into the

myocardium during the manipulations within the left

ventricle An additional fairly tight but smooth 180° curve

is formed just at the “transition” zone between the stiff and

floppy portions of the Super Stiff™ wire Regardless of the

other curves in the wire, this curve at the transition

between the end of the rigid portion of the wire and the

beginning of the “floppy” portion is essential to keep the

wire from kinking and becoming a “perforating” weapon

when “seated” in the apex of the left ventricle outside of a

catheter The diameter of the curve formed at the

“transi-tion zone” should correspond to the transverse diameter

of the particular patient’s left ventricular cavity distal to

the mitral valve During the dilation, this curve in the

transition/stiff area of the catheter will “seat” in the apex

of the left ventricle The 180° smooth curve helps to fix the

wire in the left ventricular apex while at the same time

preventing the wire (and the balloon tip, which is over the

wire) from perforating the left ventricle This 180° curve is

particularly important if a balloon “milks” forward

dur-ing the inflation of the balloons The straight portion of the

wire, which is proximal to the transition curve, should

direct the dilation balloon toward the apex rather than

across the ventricle and/or into the outflow tract of the

left ventricle The floppy portion of the wire distal to the

transition curve is directed 180° away from the inflow

of the ventricle and toward the left ventricular outflow

tract/aorta

An alternative curve and position for the support wire

is to form a 360+° “circular” loop or coil on the entire long

floppy tip of the wire, beginning with the transition zone

of the wire The wire still should have the 180° curve at the

transition zone just proximal to this 360+° looping of the

long floppy portion The “coil” of floppy wire remains

looped in the body of the ventricle as opposed to

extend-ing toward/into the left ventricular outflow tract This

positioning of the wire is simpler than directing the wire

specifically into the outflow tract, and gives just as much

stability, control and safety for the wires during the

inflation It is slightly harder to keep track of the separate

wires/balloons when two wires are looped around in the

ventricular apex

The first pre-curved Super Stiff™ wire is advanced

through one of the pre-positioned catheters and fixed with

the “transition zone” curve of the stiff wire seated in the left

ventricular apex and with the tip of the wire heading

toward the LVOT or aorta When the pig-tail catheter is

used to place the Super Stiff™ exchange wire, the pig-tail

loop of the catheter first is seated securely into the apex of

the left ventricle The Super Stiff™ wire is introduced into

the pig-tail catheter and advanced into the left ventricle

As the wire tip passes through the catheter, ideally, the

stiff “pig-tail curve” at the tip of the catheter “uncoils”

par-tially and deflects the soft tip of the wire 180° and towardthe direction of the LVOT as the wire passes through theloop of the catheter The Super Stiff™ wire is advanced

further into the pig-tail catheter until the preformed curve

at the transition zone of the wire reaches the pig-tail curve at the distal end of the catheter This results in the transition

curve of the stiff wire “seating” in the apex of the left tricle still within the pig-tail catheter

ven-It is imperative to have the straight and stiff portion ofthe Super Stiff™ wire extending entirely through the

mitral valve and to the apex of the ventricle At the same

time, the distal “end” of this stiff portion of the wire must

be protected by the bend or curve at the transition area ofthe wire, which directs the stiff straight wire away fromthe apex The placement and positioning of this wire maytake a variety of maneuvers with the sheath and/orcatheters and often is time consuming but, like most otherwire positioning for balloon dilation procedures, this par-ticular position of the wire is critical for the successful andsafe balloon dilation of the mitral valve Although it is notabsolutely necessary to have the tip of the wire in theaorta, it is desirable to have the soft portion of the wire,which is distal to the “transition” curve, heading at leasttoward the left ventricular outflow tract This positionhelps to stabilize the balloons in the correct area of thevalve and reduces ventricular ectopy due to the wires.The first catheter remains in place over the wire thatwas positioned first and maintained on a slow flushthrough a wire back-bleed valve, while the second SuperStiff™ wire is maneuvered into position in the apex of the left ventricle through the second catheter, which isalready positioned across the mitral valve and into theapex of the left ventricle The wires passing through thevalve can be visualized with TEE and/or ICE TEE/ICEwill show the position of the wires relative to the valveorifice and verify that they are passing through the center

of the orifice of the valve, and ensure that they are notpassing through some unwanted structure in the valve

or valve apparatus Once the second wire is in positionthrough the catheter, the patient is ready for the introduc-tion of the balloons and for the dilation of the valve

If not already across the mitral valve, the two longsheaths are advanced over the catheters and wires andinto the left ventricle The patient’s blood pressures andheart rate are observed closely for several minutes for anycompromise due to the increased diameters of the sheathscrossing the valve When the hemodynamic status of thepatient tolerates the two sheaths across the valve, thesheaths are maintained across the valve for the delivery

of the dilation balloons If the patient does not tolerate the two sheaths positioned across the mitral valve, the

sheaths are withdrawn back into the left atrium and tained in the left atrium The catheters that were used for

main-the introduction of main-the wires are withdrawn over main-the

wires, through the sheaths and out of the body from each

groin while the wires are maintained fixed in place and

visualized continuously on fluoroscopy Extra care must

be taken to maintain the wires in their exact positions with

the 180° “transition” curve seated in the left ventricular apex

during the withdrawals of the catheters off the wires

With both wires positioned securely across the septum

and preferably, if tolerated, through the long sheaths

passing through the mitral valve, with the “transition”

curves of the wires in the left ventricular apex and the tips

directed into the left ventricular outflow tract, the

intro-duction of the balloons is accomplished

A double-balloon mitral dilation requires at least three

experienced personnel to be scrubbed while all of the

per-sonnel in the catheterization laboratory assisting with the

dilation procedure prepare for the balloon inflations

Recording of the monitored pressures from the left

ven-tricle and left atrium are started on a continuously running,

slow-speed, permanent recording The first balloon is

passed over the wire, through the long sheath and across

the area of the mitral valve In very severe mitral stenosis,

particularly if the long sheaths could not be maintained

across the mitral valve and were withdrawn into the left

atrium, the first balloon is “parked” over the wire in the

left atrium just proximal to the mitral valve The second

balloon catheter is introduced into the second long sheath

and advanced to the left atrium or the mitral valve

depending upon where the sheaths are positioned When

the sheaths are across the mitral valve, both balloons are

advanced across the valve still within the sheaths The two

balloons are positioned side by side exactly within the

valve as compared to the earlier “freeze frame” of the left

atrial or left ventricular angiograms of the valve and as

visualized on TEE and/or ICE The sheaths are

with-drawn off the balloons and back into the left atrium The

positions of the balloons in the valve again are compared

to the earlier “freeze frame” image and/or to a hand

injec-tion angiocardiogram through one of the long sheaths

and/or a left ventriculogram through the retrograde

catheter TEE or ICE gives a good image of the balloons

across the valve and helps verify their proper position in

the valve

If the sheaths had to be withdrawn into the left atrium

from the mitral orifice before the balloons were

intro-duced, the two balloons are advanced one at a time from

the left atrium, over the two separate wires, into the mitral

valve orifice The first balloon is advanced into position

across the mitral valve If the patient tolerates this balloon

across the valve at all, the second balloon is advanced

quickly over the other wire and immediately adjacent to

the first balloon The introduction of the two balloons

across the valve is performed smoothly, but as rapidly as

possible since as soon as even the deflated balloons reach

their appropriate positions across the mitral valve, thedeflated balloons themselves produce significant obstruc-tion The centers of each balloon (between the marks at theends of the balloon) are positioned at the stenotic area ofthe valve orifice As described above, the positioning can

be verified with TEE and/or ICE when utilized The loon positions can be documented further by a hand injec-tion through one of the two long sheaths in the left atriumand compared to the earlier “freeze frame” angiogram ofthe valve, or the positions of the two balloons relative to

bal-the valve and bal-the structures within bal-the left ventricle are

visualized on a left ventriculogram performed by tion through the retrograde catheter This angiocardio-gram is also important for assessing the amount of mitralregurgitation that is present with the stiff wires (and bal-

injec-loons) across the valve prior to dilation of the valve with the

balloons

Not only should the balloons be across the mitral valve, but the proximal ends of the balloons must be wellaway from the atrial septum while the opposite ends aredirected toward the apex of the left ventricle Neither balloon should be bent or turning across the ventricularcavity either posteriorly toward the mitral apparatus oranteriorly, “across” the ventricle and toward the outflowtract If the balloons are inflated in either of these abnor-mal positions, disruption of the mitral apparatus is likely

to occur

When both balloons are in their proper positions acrossthe valve, the two balloons are inflated simultaneouslyusing pressure-monitored and controlled indeflators.Unless the patient is very unstable with the deflated bal-loons across the valve, the balloon inflations are relat-ively slow and very controlled The balloon inflations are

visualized continuously fluoroscopically and recorded on

either slow-frame-rate biplane angiograms or biplane

“stored fluoroscopy” The inflation of the two balloons iscontinued until the recommended maximum inflationpressure of each balloon is reached or the “waist” in the

balloons created by the stenosis disappearsawhichever

comes first The balloons should not move in their tions within the valve during the inflations and a single,discrete “waist” should appear around the two balloons

posi-at the level of the stenotic valve The appearance of the

“waist” on the balloons and then the opening of the valve with the disappearance of the waist are also visibleand can be observed on TEE or ICE performed during theballoon inflation If either of the balloons begins to moveeither further into, or out of, the ventricle or if an unusual

or second “waist” appears on either balloon, especially deepwithin the ventricle, the inflation is stopped instantly, theballoons are deflated immediately and rapidly and, oncethey are fully deflated, withdrawn out of the valve

A very forceful displacement of the balloons into the

ventricle during the pressure inflation could continue to

push the balloon tip, along with the stiff wire, even with

the curve at its transition zone, into, and actually through

the ventricular wall!! If a balloon that is displaced into the

ventricle does not push the wire with it, but follows the

stiff curve on the “transition” zone of the wire, it “turns”

toward the outflow tract and tracks perpendicularly across

the mitral apparatus Further inflation in this position

could disrupt the mitral apparatus An “abnormal waist”

on a balloon is created by a balloon that is positioned

abnormally through a chorda or in a fused papillary

muscle in the left ventricle The presence of any abnormal

waist should result in the immediate stopping of the

inflation of the balloon Further inflation of the balloon in

such abnormal positions very likely will disrupt the mitral

apparatus Displacement of the balloons backwards into

the left atrium pushes the balloons actually into the

intera-trial septum Continued inflation with the balloon pushed

backwards dilates a large and possibly permanent

open-ing in the atrial septum

If the inflation is interrupted, the inflation angiogram

and the TEE/ICE during the inflation are reviewed and

the balloons and/or the wires are repositioned to more

stable locations When comfortable with the new

posi-tions of the balloons and wires, the inflation is repeated

The inflation again is slow, is recorded on biplane

angio-graphy and observed on TEE/ICE following the same

precautions concerning abnormal positioning and/or

movement during each subsequent inflation of the

bal-loons Once the maximum pressures of the balloons are

reached or the “waists” on the balloons disappear, the

bal-loons are deflated as rapidly as possible and the patient’s

hemodynamics (vital signs) are allowed to stabilize

During the inflation of the balloons, the systemic blood

pressure drops dramatically as a result of the almost

com-plete obstruction of the forward flow of blood through the

mitral valve even when using the double-balloon

tech-nique If the systemic pressure does not begin to return

immediately with just the deflation of the balloons, the

bal-loons are withdrawn over the wires, which remain fixed

in place, and out of the valve orifice in order to allow freer

prograde flow through the valve Once the patient has

stabilized either with the balloons still across the valve

or after reinserting the balloons across the valve, the

inflation/deflation cycle is repeated two to four more

times By either advancing the balloons further into the

ventricle over the wire or withdrawing them slightly

back toward the left atrium by pushing the wires forward,

the position of the balloons is changed slightly during

each repeat inflation of the balloons This maneuver is

to ensure that the maximum parallel surfaces of the

balloons are inflated simultaneously and exactly in the

narrowest portion of the stenotic valve The positioning

is verified with TEE or ICE during each change of the

balloons’ position

In very severe mitral valve stenosis when even onesheath positioned across the valve cannot be tolerated oreven the first deflated balloon crossing the valve causes

a significant drop in systemic pressure, preparations are

made for an initial, rapid, single-balloon dilation in order

to open the valve partially before the double-balloon dilation The partial opening of the valve created by thesingle-balloon inflation allows the patient to tolerate thetwo deflated balloons across the valve for a subsequent,double-balloon dilation The wire(s) is (are) already inplace across the valve With the previous “freeze frame”images aligned with the bony landmarks of the thorax andone of the two balloons ready for immediate inflation, theballoon is advanced across the mitral valve and a rapid,but controlled inflation with biplane angiographic and

TEE or ICE recording is started Exactly as with the

con-trolled double-balloon inflation, if there is any

displace-ment of the balloon or the “waist” does not appear in its proper (expected) location as seen on angiography orTEE/ICE, the inflation is stopped and the balloon isdeflated rapidly and withdrawn out of the valve Thepatient is allowed to stabilize and the procedure repeatedwhen the balloon/wire position and inflation appears correct and stable Very rarely, a single-balloon dilation

must be accomplished before even the second wire can be

positioned for the double-balloon dilation When a “goodwaist” appears on the single balloon and the “waist” issuccessfully abolished with the balloon inflation, usuallythe procedure can be continued with a double-balloondilation as described above

How the results of the dilation are assessed ately after the dilation depends upon the placement of the

immedi-various catheters prior to the actual dilation procedure and

on whether TEE or ICE imaging is utilized With the grade catheter already positioned in the left ventricle,simultaneous left ventricular and left atrial pressures areobtained immediately through the retrograde catheterand the side arm of one of the long sheaths that are in theleft atrium The estimate of any residual gradient and

retro-of the diameter retro-of the valve orifice is also available fromthe TEE or ICE If the gradient across the mitral valve

is abolished or minimized, then the dilation procedure has accomplished the opening of the valve The variouscatheters are removed regardless of the other findings

If there still is a significant gradient across the valve, thedecision must be made whether further dilation of thevalve can and should be accomplished An estimate of the degree of mitral regurgitation is made with the TEE

or ICE imaging A left ventricular angiocardiogram is performed to “quantitate” any mitral valve regurgitationvery roughly If significant mitral regurgitation was pro-duced by the dilation, regardless of any residual gradient,

no further dilation is performed If there is no, or minimal,mitral regurgitation and still a residual gradient, the

angiograms of the balloon inflations and the TEE

informa-tion are analyzed to determine if further dilainforma-tion is

pos-sible The diameter of the valve annulus and the combined

diameters of the fully inflated balloons in the annulus are

remeasured accurately and together in the same

angio-graphic sequence and by TEE or ICE If the combined

diameter of the two balloons is less than 1.6 times the

diameter of the mitral annulus in its largest diameter and

the dilation did not produce significant mitral regurgitation,

then larger diameter balloons are used for further dilation

The larger diameter balloons are introduced with the

same technique used for the initial balloons Occasionally

when a larger diameter balloon is used, the diameter of

the long sheath will also have to be increased In that

situ-ation the original sheath is withdrawn over the

support-ing exchange wire, which is maintained in place across the

mitral valve and in its position in the left ventricular apex

The new, larger French sized sheath with its dilator is

advanced over the wire, into the left atrium and, if

toler-ated, across the mitral valve This is repeated with the

other sheath if two larger balloons are to be used The

larger diameter balloons are introduced through the new

larger sheaths The dilation procedure is carried out with

the larger balloons exactly as with the initial dilation

balloons Usually when the valve is being dilated further

during the same catheterization procedure, the patient

remains more stable with the sheaths across the valve and

during the subsequent balloon inflations

Reassessment of the results of the dilation is repeated

exactly as after the initial dilation Once the gradient has

been eliminated or the waists on the larger balloons no

longer reappear during early balloon inflation, the

dila-tion procedure is completed and the diladila-tion balloons are

removed When there is a residual gradient or there is the

possibility of further dilation of the valve, the presence of

mitral regurgitation is assessed with a repeat left

ventricu-lar angiocardiogram and TEE/ICE before the wires and

balloons are removed from the valve TEE or ICE is more

sensitive at detecting tears and other disruption of the

valve leaflets and valve apparatus than angiograms If

there is significant mitral regurgitation and no valve

dis-ruption, but with the wires and balloons still across the

mitral valve, the balloons are withdrawn back into the

sheaths in the left atrium The TEE and the left ventricular

angiocardiogram are repeated If there still is significant

mitral regurgitation, the dilation balloons are removed

from the sheaths and replaced with end-hole catheters,

which are advanced into the left ventricle over the wires,

and the wires are withdrawn carefully through these

catheters The wires with their preformed curves readily

catch on the mitral valve apparatus, and must be

with-drawn through catheters that are fixed in the ventricle.

Once the wires are removed, the catheters are withdrawn

back into the left atrium/sheaths TEE/ICE and the

angiocardiogram are repeated once all balloons, wiresand catheters are out of the mitral valve

TEE or ICE interrogation of the valve and the left

ven-tricular angiocardiogram are repeated with nothing across

the mitral valve The presence of mitral regurgitation with

nothing crossing the valve represents real mitral valveinsufficiency! No further dilation of the valve is con-sidered in the presence of significant mitral regurgitation

If, however, the mitral regurgitation disappears, or even isreduced markedly when the wires are removed from thevalve, then the decision is made on the basis of the resid-ual gradient and the valve anatomy seen on TEE or ICEwhether the dilation needs to be repeated If the dilation

is to be repeated, it means almost starting from scratch,except that the transseptal sheaths are still in place acrossthe atrial septum The catheters and then the wires arereplaced across the mitral valve, larger balloons inserted,and the dilations repeated as described above

Once the final dilation is completed, pressure ments are recorded, a left ventricular angiocardiogram,preferably in the same view as utilized for the original leftventriculogram, and a repeat TEE or ICE analysis of thevalve are performed ICE imaging of the valve can nowprovide a direct image of the valve orifice facing it fromthe left atrial side through one of the large long sheathsthat are still in the left atrium A repeat left atrial angiocar-diogram, again in comparable views to the pre-dilationleft atrial angiogram, is recorded to demonstrate the change

measure-in the diameter of the valve orifice, the change measure-in valvemotion, changes in the emptying of the left atrium, andthe size and amount of leak across the interatrial septum

as a result of the transseptal approach

Occasionally and although it is not advocated, when verylarge balloons and, in turn, large sheaths must be used toaccommodate the balloons, some operators utilize a double-

balloon technique for dilation of the mitral valve without

the long sheaths remaining in the left atrium In that cumstance, the two venous punctures and two separatetransseptal punctures are performed with 7- or 8-Frenchtransseptal sets It still is important that the two transseptal

cir-punctures are at least one centimeter away from each other

so that the two holes do not “coalesce” into one Once thetransseptal puncture is completed, the end-hole cathetersand wires are positioned exactly as for a double-balloondilation through long sheaths Once the wires are in posi-tion, the original transseptal sheaths are removed over the wires and the dilation balloons introduced directlythrough the skin over the wires When very large “profile”balloons are necessary for the dilation, the holes in theatrial septum often first must be dilated with a smaller,6–8 mm diameter angioplasty balloon before the deflated,large dilating balloons will pass through the septum Oncethrough the septum, the dilation is carried out exactly aswith two balloons delivered through two long sheaths

The only “advantages” of not introducing the two

bal-loons through long sheaths are of not having the long

sheaths in the “left heart” for as long and that the “factory”

folded balloons introduced directly over the wires initially

are smaller in outside diameter than the outside diameter

of the sheaths which they otherwise would be passing

through However, once the balloons are inflated and

deflated in the body their deflated “profiles” and

dia-meters are much larger than the comparable sheaths

There are multiple disadvantages of not using long

sheaths, no matter how much larger they might be The

large dilation balloons have horrible deflated profiles, and

when withdrawn through the atrial septum they make

excellent “septostomy” devices, which are very likely to tear

and extend the openings in the septumaresulting in very

large communications or tearing the two puncture sites so

that they coalesce into a single very large opening in the

septum The deflated large balloons are equally traumatic

to the smaller more peripheral venous structures and

often disrupt the introductory veins as the balloons are

withdrawn, resulting in later total occlusion of the vein

When the balloons are delivered directly over the wires,

there is no way of measuring left atrial pressure

immedi-ately after the dilation for assessment of the results of

the dilation while still keeping the two wires in position

across the mitral valve and while still keeping the two

balloons in the left atrium Either one balloon must be

removed over a wire, replaced with an end-hole catheter,

and then the wire completely removed, or a third

trans-septal puncture must be performed to introduce a third

catheter into the left atrium for the measurements The

third transseptal is possible with an additional long

transseptal sheath/dilator introduced “piggy-back”

adja-cent to one of the other femoral venous punctures

This third transseptal system can be as small as a 6-French,

since it will only be used for pressures and possibly

angiography

With the major disadvantages and much greater

poten-tial for long-term complications when the balloons are

not delivered through long sheaths, it is now standard

practice to use the long transseptal sheath technique for

double-balloon dilation of the mitral valve Regardless

of how large the diameters of the long sheaths are, they

always are less traumatic to the atrial septum and venous

structures than “bare” deflated balloons

Single standard balloon dilation of mitral valve

The single “standard” balloon dilation of the mitral valve

is still advocated by some operators for mitral dilations

The single standard balloon technique certainly is useful

for the very rare mitral valve dilation when the approach

is not from the femoral veins, and particularly the hepatic

and jugular vein approaches, which involve significantly

different transseptal and dilation procedures A single

balloon also is used in very small infants where the mitral

annulus is less than 10 mm in diameter The technique forthe transseptal puncture, the acquisition of the hemody-namics, performance of the angiography and the position-ing of a single stiff support wire for the procedure, all arethe same for a single balloon dilation approached from the femoral vein as described for the first wire of the double-balloon technique

For a mitral valve dilation using a single, standardangioplasty balloon, the diameter of the balloon usedshould be the same as the diameter as the mitral annulus.Because of the relatively large diameter of the mitral

annulus, this of course necessitates a very large balloon

re-lative to the patient’s body size Because of the necessarylong “taper” of the ends of these very large balloons, they

are also extremely long compared to the usable, parallel

walled sections of the balloons When the usable length

of these large balloons is “centered” in the valve annulusfor the inflation, the two ends of the balloon often

extend from the apex of the left ventricle back into the

atrial septum!

Because of the very large diameter of the balloon that isnecessary in the larger child or adult for a single-balloondilation of the mitral valve, these balloons have very large

deflated profiles, and there often is not a large enough long

sheath available to accommodate the larger balloon evenwith the initial “factory” fold on the catheter As a con-sequence, the balloon dilation catheter is usually passed

directly over the wire and not through a long transseptal

sheath or even a short venous sheath A separate dilation with a separate smaller balloon of the introduc-tory site into the subcutaneous tissues, into the vein andacross the atrial septum, often is necessary before the verylarge sized mitral dilation balloon can be advanced to themitral valve The pre-dilation of the subcutaneous tissuesand the vein is accomplished with a separate dilator ordilation balloon that is larger than the deflated diameter ofthe mitral dilation balloon The atrial septal opening isdilated with a 6 or 8 mm, low-profile, dilation balloon,which is advanced to the septum over the same wire Afterthe opening in the septum is enlarged, the large single mitraldilation balloon is advanced over the pre-positioned wire,through the septum and across the mitral valve

pre-In the very small infant, the single balloon for mitralvalve dilation is delivered through a long transseptalsheath In that specific circumstance, the long sheathremains in the left atrium and is available for immediatehemodynamic measurements after the dilation The longsheath also protects the intracardiac and venous struc-tures from the rough profile of the deflated balloon duringits withdrawal

Similar techniques and precautions are observed ing the inflation of the single balloon as are used in the

dur-double-balloon technique The single balloon has to be

inflated and deflated as rapidly as possible and carefully

but rapidly withdrawn from the valve back into the left

atrium over the wire immediately after its deflation to

allow the return of the systemic cardiac output The large

single balloon inflates and deflates much slower than two

separate balloons used for the same dilation so that the

obstruction of cardiac output is much longer during the

dilation procedure As a consequence there usually is a

very significant drop in heart rate and blood pressure, and

a more prolonged recovery period or even a transient

“resuscitation” of the patient is required after the single

balloon is deflated

The single, standard balloon technique superficially

appears simpler than any of the other mitral valve dilation

techniques It does avoid the second venous puncture, the

second transseptal puncture, and the positioning of two

wires across the valve and in the left ventricular outflow

tract This appears as an advantage to very inexperienced

operators, however, to gain this small advantage, there

are many and significant disadvantages, which have

already been described The slower inflation/deflation of

the larger balloon has already been mentioned In larger

patients, the very large diameter single dilation balloon

catheters cannot be delivered or positioned through a long

sheath Reassessment of the hemodynamics immediately

after the single-balloon dilation can be performed only

by echocardiography or by placing a second catheter in

the left atrium from a second venous puncture and second

transseptal puncture! Without the second catheter in the left

atrium, the balloon catheter must be removed completely

out of the body and replaced with a catheter through

which pressures can be recorded By the use of a

Multi-Track™ catheter for this post-dilation assessment, at least

the wire does not have to be removed as well! If the results

indicate that further dilation is required, an even larger

balloon would have to be introduced

A much greater problem with the single standard

bal-loon dilation technique for the mitral valve is that a much

larger hole is purposefully made in both the femoral vein

and the atrial septum to introduce the large diameter,

large-profile balloon Even worse, when these very large

dilation balloons are deflated, they develop an even

larger, horribly irregular and rough profile This profile is

guaranteed to tear the septum further as the deflated

bal-loon is withdrawn directly through the septum, and can

be very traumatic to the iliofemoral venous system when

withdrawn out of the vein Because of these

disadvant-ages, this technique is not recommended

Bifoil balloon dilation of the mitral valve

For a while, with the idea of creating a more linear dilation

profile as occurs with a double-balloon dilation, but at the

same time, still being able to use a single puncture and single wire system, “bifoil” balloon catheters were de-veloped and used for valve dilations These bifoil ballooncatheters had two balloons side by side attached to thesame single catheter shaft and central lumen The bifoilballoon catheter was passed over a single wire similar to

a single standard balloon technique, however once the

“balloon” was in position in the orifice of the valve, thereactually were two balloons side by side, which were fixedsecurely in their side-by-side relationship

Unfortunately, all the advantages of a single punctureand single wire are obviated by the multiple disadvant-ages of the bifoil balloons The bifoil balloons could not

be introduced through any sheaths of any length Because

of the large and irregular profiles of the bifoil balloonseven before they are inflated, it was necessary to pre-dilate

the introductory venous tract, the atrial septum, and even the mitral valve itself with a 10 mm angioplasty balloon before

the bifoil system could be introduced The bifoil balloonshad problems with unequal inflation and the inability todeflate one or both balloons After the dilation, there is nomeans of measuring left atrial pressure without removingthe balloons completely Even when deflated properly,bifoil balloons had an even worse and more traumatic,deflated profile than even one large, single standard balloon As a consequence bifoil balloons were almostguaranteed to leave a permanent atrial septal defect andpermanently traumatize the introductory vein Because ofthe real disadvantages compared to any possible advant-

ages, these balloons faded from use and production and

fortunately are no longer available

Double-balloon, double-wire, through single

vein and single transseptal puncture: (Block™)

technique of mitral dilation

The double-balloon dilation over two wires introduced

through a single venous and single transseptal puncture

was developed to “simplify” and expedite the procedure

by eliminating one venous and one transseptal puncture.The special double-lumen Block™ catheter was developedspecifically for this procedure to carry the two wiresthrough the single puncture A single catheter was intro-duced percutaneously into one femoral vein The rightheart catheterization and cardiac outputs were obtained

A single transseptal procedure using a Mullins transseptalset was performed The hemodynamics and angiocardio-grams were recorded from the left heart using the catheterthrough the transseptal sheath as described previously

in this chapter

Once the anatomy and hemodynamics were obtained,

an end-hole catheter was maneuvered through the mitralvalve, into the left ventricle and to the left ventricularoutflow tract A stiff exchange length guide wire was