Ebook Reoperations in cardiac surgery: Part 2

(BQ) Part 2 book Reoperations in cardiac surgery has contents: Reoperations after mustard and senning operations, reoperations after arterial switch operation, aortic valve reoperations, aortic root replacement, reoperations for atrioventricular discordance,... and other contents.

Reoperations After Mustard and Senning

Operations

J Stark

Introduction

Senning introduced the physiological repair of

transposition of the great arteries in 1958

(Senning 1959) and Mustard published his

experience with the atrial switch in 1964

(Mustard 1964) The Mustard operation soon

became the operation of choice, and survival

rates of over 90% for patients with simple

transposition were reported (Waldhausen et al

1971; Lindesmith et al 1973; Ebert et al 1974;

Stark et al 1974a) The original concept of the

Mustard operation was a two-stage correction

A Blalock-Hanlon atrial septectomy enabled

a sick infant to survive Because of the fear

that the small size of the atria would preclude

successful repair, the Mustard operation was

often delayed into the second or third year

of life The balloon atrial septostomy was

introduced by Rashkind and Miller in 1966

(Rashkind and Miller 1966) This considerably

improved the survival of infants with

trans-position of the great arteries However, the

improvement achieved by a balloon sept ostomy

did not usually last as long as the improvement

following a surgical septectomy Attempts,

therefore, were made to lower the age for an

elective Mustard operation, and soon results

which were comparable with or better than the results achieved in older children were reported (Aberdeen 1971; Stark et al 1974a; Bailey et

al 1976; Oelert et al 1977; Turley and Ebert 1978) The advantage of early balloon septostomy followed by a Mustard operation during the first year of life rapidly became apparent

Reports of complications of the Mustard operation such as SVC obstruction (Mazzei and Mulder 1971; Stark et al 1974b) and pulmonary venous obstruction (Stark et al 1972; Driscoll et al 1977; Oelert et al 1977) led to several technical modifications of the original Mustard operation Although some

of these modifications reduced postoperative complications, others actually increased them Brom reintroduced the Senning operation in

1975 (Quagebeur et al 1977); the incidence of complications was reduced significantly but not completely eliminated Today, both the Senning and Mustard operations offer excellent early and good medium-term results Recent reports of the arterial switch operation for neonates with simple transposition (Jatene et

al 1975; Castaneda et al 1974; Quaegebeur

et al 1986) suggest that the J atene operation may become the operation of choice for this group of patients

As is often the case in surgery of infants and

young children, some complications may be

growth-related, manifesting themselves only

years after the original operation For this

reason, it is important to follow these patients

for many years It is equally iinportant to be

familiar with the diagnosis of the complications

and with the surgical techniques of their repair,

even though the original operation may not be

in use any more

Problems

Mustard Operation

The following problems/complications have

been reported after the Mustard operation:

1 Systemic venous obstruction (SVe, IVC)

2 Pulmonary venous obstruction

3 Tricuspid valve incompetence

4 Baffle leaks

5 Residual/recurrent ventricular septal defect

6 Residual/recurrent left ventricular outflow

tract obstruction

7 Right and left ventricular dysfunction

8 Arrhythmias

Some of these complications may not

mani-fest themselves clinically, and are discovered

only on routine restudy (isolated obstruction

of the sve, small baffle leaks) Other

compli-cations may require medical treatment

(arrhyth-mias, ventricular dysfunction) In this chapter

we shall concentrate only on those

compli-cations which require surgical treatment:

sys-temic and pulmonary venous pathway

obstruc-tion, leaks in the baffle, and tricuspid valve

incompetence Residual ventricular septal

defects and left ventricular outflow tract

obstruction are described in detail elsewhere

(see pp 165-167 and 285)

Systemic Venous Obstruction

Incidence and Causes sve obstruction is much

more common than obstruction of the IVe

Frequently it is the intracardiac part of the sve channel, rather than the sve itself, which becomes narrow In the Ive channel, the obstruction usually occurs between the coron-ary sinus and the right inferior pulmonary vein Pathway obstruction may have several causes: construction of too narrow a pathway, inad-equate resection of the upper margin of the interatrial septum, and thrombosis of the pathway possibly originating on the raw area remaining after resection of the septum Nar-rowing of the sve at the cannulation site can also occur Late obstruction may be caused by thickening and/or contraction of the baffle The incidence of systemic venous pathway obstruction varies in different series Venables

et al (1974) reported 14 cases of sve tion among 20 restudied patients; 8 had symp-toms Park et al (1983) reviewed 78 patients;

obstruc-33 had gradients over 5 mmHg Eighteen obstructions were seen; of these, six required reoperation Silverman et al (1981) observed

5 partial and 4 complete obstructions in a series

of 18 restudied patients A high incidence of systemic venous pathway obstruction was also reported by Marx et al (1983) Of their 59 survivors of the Mustard operation, 32 had gradients, with 11 requiring reoperation

In our experience a higher incidence of sve obstruction was observed in patients in whom

a Dacron patch was used for the Mustard repair From the experience of other authors

it seems likely that the shape of the baffle is more important than the material Egloff et al (1978) observed systemic venous obstruction in

7 out of 10 patients in whom a shaped" patch was used A dumbbell-shaped patch resulted in 25 obstructions among 84 operated patients, while only 2 obstructions were observed among 58 patients with a trouser-shaped pericardial patch (Stark et al 1974a) Trusler et al (1980) has reported a higher incidence of systemic venous obstruction in the latter part of their series (10/100 compared with 5/105) This was probably due to the less aggressive resection of the superior part of the interatrial septum Avoidance of excessive resection decreased the incidence of arrhyth-mias in their series, but it increased the incidence of sve obstruction

"butterfly-Inferior vena cava obstruction is much less common (Trusler et al 1980 - 3/192 sur-

vivors) Partial obstruction of both the SVC

and IVC is a more serious complication than

isolated SVC obstruction The patient may

present with a low cardiac output Thrombosis

of the IVC has been described after

preoperat-ive cardiac catheterisation (Venables et al

1974) IVC obstruction is particularly rare if

the coronary sinus is opened widely into the

left atrium during the Mustard operation

Barratt-Boyes (Kirklin and Barratt-Boyes 1986)

has seen only one IVC obstruction among 166

patients (0.6%)

Diagnosis Some patients with SVC

obstruc-tion are asymptomatic Others develop

puffi-ness of the eyelids or facial oedema, pleural

effusion or even chylothorax Tortuous venous

collaterals on the chest wall usually develop in

the presence of severe obstruction only An

increasing head circumference with widening

of the cranial sutures and delayed closure of

the fontanelles has been described (Silverman

et al 1981)

Significant IVC obstruction causes

hepato-megaly, ascites and leg oedema Protein-losing

enteropathy has been described (Moodie et al

1976) SVC obstruction can be diagnosed

non-invasively by Doppler ultrasound (Wyse et al

1979) or two-dimensional contrast

echocardi-ography (Silverman et al 1981) Cardiac

cath-eterisation and cineangiography should be

performed prior to the operative revision This

investigation demonstrates not only the· exact

location, length and severity of the obstruction,

it also visualises the width of the non-obstructed

channel It is important to detect any other

residual/recurrent lesions so that these can be

repaired at the time of revision of the systemic

venous pathways Asymptomatic isolated SVC

obstruction does not require treatment All

IVC obstructions and symptomatic SVC

obstructions are indications for operative

revisions Recently, successful balloon

dila-tation of partially obstructed pathways has been

described by the Boston group (Lock et

al 1984) We have used balloon dilatation

successfully It would seem reasonable,

there-fore, to attempt to dilate such pathways during

the diagnostic cardiac catheterisation Even if

a perfect result is not achieved, dilatation can

be repeated or surgery considered at a later

date In the meantime the symptoms will usually be relieved

Pulmonary Venous Obstruction Causes and Incidence Pulmonary venous obstruction is a less frequent but much more serious complication of the Mustard operation

It is probably caused by a redundant baffle which becomes adherent to the lateral right atrial wall It occurs more frequently when Dacron is used for the baffle (Driscoll et al 1977; Oelert et al 1977) Occasionally, isolated left pulmonary vein stenosis occurs, but more frequently the stenosis is anterior to the entry

of the right pulmonary veins The ostium may

be very small and divides the pulmonary venous atrium into a posterior and anterior compartment Driscoll et al (1977) observed pulmonary venous obstruction in 9 of their 25 survivors, Oelert et al (1977) in 7 of 43 survivors Eight among the 48 restudied patients at the Mayo Clinic (Hagler et al 1978) and 10 of 376 survivors in Toronto (Trusler 1984) developed pulmonary venous obstruc-tion We have reported 4 pulmonary venous obstructions among 113 survivors of the Mus-tard operation (Stark et al 1972) Pulmonary venous obstruction was not seen by Barratt-Boyes in patients in whom he used a V-Y atrioplasty (Kirklin and Barratt-Boyes 1986) Likewise, obstruction is rare in the series where the pulmonary venous atrium is enlarged, even when the operation is performed in infancy (Turley and Ebert 1978; Stark et al 1980)

Diagnosis Tachypnoea, dyspnoea, cough, fatigue and decreasing exercise tolerance are the common symptoms Mild cyanosis may

be present The condition may be wrongly diagnosed as asthma or pneumonia (Driscoll

et al 1977) Pulmonary venous congestion or interstitial pulmonary oedema is seen on the chest radiograph The diagnosis of pulmonary venous obstruction may be made by two-dimensional echocardiography It is confirmed

by cardiac catheterisation; the catheter has

to be passed retrogradely through the right ventricle and the tricuspid valve across the stenotic area into the pulmonary veins On angiocardiography ,(direct or pulmonary artery

injection) narrowing is best seen in the lateral

projection Urgent reoperation is indicated for

all patients with pulmonary venous pathway

obstruction Recently we have successfully used

balloon dilatation of this obstruction The

balloon was passed retrogradely through the

aortic valve, right ventricle and tricuspid valve

into the pulmonary venous atrium and through

the stenotic area

Leaks in the Baffle

A significant baffle leak is rare Trusler et

al (1980) reported 12 in his series of 60

recatheterised patients (20% ), but only 3

required reoperation Park et al (1983)

described small baffle leaks in 22 (25%)

patients The leak was detected by oximetry in

four, while in 18 it was visualised only by

cineangiography None of their patients

required surgery

Indications for surgery would be similar to

those for atrial septal defect with a left-to-right

shunt If the SVC or IVC pathways are also

obstructed, a baffle leak above the site of

obstruction may cause considerable

right-to-left shunting This is repaired at the time of

the relief of the pathway obstruction

Tricuspid Valve Incompetence

Causes and Incidence Mild to moderate

tricus-pid valve incompetence can be seen in some

patients before the Mustard operation (Tynan

et al 1972) The abnormalities of the tricuspid

valve are more common in patients with TGA

and VSD Huhta et al (1982) has reviewed

121 autopsy specimens with TGA and VSD

and found structural abnormalities of the

tricuspid valve in 38 (31%) Valve dysplasia,

straddling, double orifice, accessory tricuspid

valve tissue and abnormal chordal attachment

were observed

The reported incidence of tricuspid valve

incompetence after the Mustard operation

varies It is speculated that the tricuspid valve

can be injured when the baffle is sutured close

to the tricuspid valve annulus or when the VSD

is repaired through the tricuspid valve We

have seen the tricuspid valve and/or the chordae

become adherent to the VSD patch

Incom-petence can also develop secondary to right ventricular dysfunction/failure or to arrhyth-mias Takahashi et al (1977) and Marx et al (1983) did not see serious tricuspid valve incompetence in respective series of 110 and

59 survivors of the Mustard operation Trusler

et al (1980) has reported 10 cases of mild tricuspid incompetence among 192 survivors

in Toronto In our series of 563 Mustard operations, tricuspid valve replacement was performed in 6 patients

The incidence of serious tricuspid ence is higher in patients operated on for TGA and VSD Hagler et al (1979) reported a high incidence of this complication from the Mayo Clinic They found 7 mild and 7 moderate tricuspid valve incompetences among 33 restud-ied asymptomatic patients and 4 mild to moderate and 2 severe among 16 symptomatic patients Four out of 17 patients operated for TGA and VSD by Barratt-Boyes had moderate

incompet-to severe incompetence (Kirklin and Boyes 1986) In Park's series, 6/24 patients with TGA and VSD developed incompetence;

Barratt-2 required surgery (Park et al 1983)

Diagnosis The patients present with increasing

breathlessness, a cough and fatigue A systolic murmur is heard along the right sternal border The chest radiograph will show cardiomegaly, pulmonary venous congestion and later pul-monary oedema

The tricuspid valve is best assessed by sectional echocardiography Anomalies, such

cross-as straddling, overriding and prolapse, are usually well demonstrated Doppler echocardi-ography detects a regurgitant jet; the degree

of regurgitation can be estimated Cardiac catheterisation and angiography should exclude additional residual/recurrent lesions and assess the right ventricular function

Mild to moderate tricuspid valve ence is often tolerated; if severe, an operation

incompet-is indicated Tricuspid valve incompetence secondary to right ventricular dysfunction may

be considered for an alternative treatment Mee (1986) has suggested that the pulmonary artery be banded unless the left ventricular pressure is considerably elevated After this preliminary banding, the Mustard operation is changed into an arterial repair (arterial switch) (see Chap 16, p 217)

Residual! Recurrent VSD

ResiduaVrecurrent VSD can occur, as it does

after VSD repair in other anomalies The

diagnosis and treatment is described in Chapter

12 (see p 161)

Residual! Recurrent Left Ventricular Outflow

Tract Obstruction

It is often difficult to relieve left ventricular

outflow tract obstruction (LVOTO) at the time

of the Mustard operation This is particularly

so If the Mustard operation is performed during

the first 3-6 months of life L VOTO is often

~ell tolerated in patients whose LV pressure

IS less than systemic and in whom the pulmonary

artery pressure is close to normal Under such

circumstances we do not attempt to relieve

LVOTO; the obstruction rarely progresses

(Park et al 1983) We have serially

recatheter-ised several patients over a period of 15 years·

the gradient remained more or less the same:

In only a few patients, the obstruction develops

late after the operation, or, if present originally,

progresses

The diagnosis of L VOTO is made by

cross-sectional echocardiography, cardiac

catheteris-ation and angiography Detailed assessment of

~h~ anatomy of the obstruction and its severity

is Important before reoperation is indicated

An attempt should be made to distinguish

obstruction which could be relieved at a late

operation (valvar stenosis, subvalvar membrane

or aneurysm of the membranous part of

the interventricular septum) from obstruction

which must be bypassed (long fibromuscular

tunnel or abnormal attachment of the mitral

valve)

~eoperation is indicated in symptomatic

patients whose LV pressure is at systemic level

and in asymptomatic patients with

supra-systemic LV pressure

Ventricular Dysfunction

Right ventricular (RV) function may be

reduced after the Mustard operation;

impair-ment of the LV function is less common The

cause of dysfunction is not clear; it has been

suggested that the morphological right ventricle

is not capable of functioning normally as a systemic ventricle Ventricular dysfunction is more common in patients in whom the VSD was ~losed in.addition to the Mustard operation, particularly 10 those in whom the VSD was closed through a right ventriculotomy (Park et

end-1984) Hagler et al (1979) has studied 37

as~mptomatic patients after the Mustard ation The RV ejection fraction calculated for this group of patients was found to be significantly below normal, and RV end-dias-tolic volume was significantly increased LV

oper-~u~ction was relatively well preserved A high

IOcid~nce of RV dysfunction at rest and during exercise was also demonstrated in a group of

26 asymptomatic patients studied by Murphy

et al (1983) In our group, Weller has shown

a statistically significant (p=O.OI) reduction in maximal working capacity in a group of 45

asymptomatic patients studied 5-12 years after the ~ustard operation (Stark et al 1980)

Despite the decreased exercise tolerance all '

our patients were asymptomatic and were leading a normal life The same observation has been made by other authors (Mathews et

al 1983; Ramsay et al 1984)

The reports of RV dysfunction have

prompt-ed the exploration of alternative techniques

of ~orrec~i.on for TGA, especially techniques which utIhse the left ventricle as a systemic ventricle Mee (1986) has demonstrated recently that some patients with impaired RV function following a Mustard operation can be treated by pulmonary artery banding followed

by an arterial switch operation (see Chap 16,

p 220)

Rhythm Disturbances

Serious arrhythmias (atrial fibrillation or ter, atrioventricular dissociation) were seen more frequently after operations performed in

flut-earlier years (Breckenridge et al 1972; EI Said

et al 1972; Ebert et al 1974; Beerman et al

1983; Hayes et al 1986) It is not clear why

the incidence of reported rhythm disturbances

has decreased considerably in recent years

(Turley et al 1978; Ullal et al 1979; Trusler

et al 1980; Deanfield et al 1989) Possibly a

better knowledge of the exact position of the

sinus node, sinus node artery and

atrioventric-ular node has enabled surgeons to protect these

structures better during the Mustard operation

Ebert et al (1974) have reported a higher

incidence of arrhythmias in patients who had

the coronary sinus cut open; however, this was

not confirmed by Clarkson et al (1976) Fewer

arrhythmias were seen in patients in whom a

less extensive resection of the superior part of

the interatrial septum was carried out (Trusler

et al 1980)

The incidence of post Mustard arrhythmias

varies in reported series Southall et al (1980)

have pointed out that some arrhythmias may

be detected on Holter monitoring even before

the Mustard operation Our prospective study

(Deanfield et al 1989) did not confirm this

finding Changes of P wave amplitude and

contour are seen in almost all patients after

the Mustard operation (EI Said et al 1972)

Atrial fibrillation, atrial flutter and

atrioventric-ular dissociation occurred frequently in earlier

series (Breckenridge et al 1972; Ebert et al

1974); fortunately, the current incidence of

these is very low Sick sinus syndrome (sinus

bradycardia with sinus arrest and junctional

escape) was the predominant arrhythmia in the

experience of Hayes et al (1986) Junctional

rhythm does not usually cause any problems

Episodes of supraventricular tachycardia are

more serious; they occur in a small percentage

of patients (Hayes et al 1986) Some

arrhyth-mias may only become "unmasked" during

maximal exercise testing (Mathews et al 1983)

Late deaths have been described in several

series after the Mustard operation Some of

these may possibly have been caused by

arrhythmias (Aberdeen 1971; Lewis et al 1977;

Hayes et al 1986)

Patients discharged from hospital in sinus

rhythm may lose this rhythm later At Green

Lane Hospital, Auckland, 72% of patients

were in sinus rhythm 1 year after the Mustard

operation This number decreased to 56% at

5 years and 50% at 10 years (Kirklin and Barratt-Boyes 1986) In our postoperative study (Deanfield et al 1989), we have followed patients with 24-h Holter monitoring before and after the operation All were in sinus rhythm before the operation and 91 % at discharge from the hospital The incidence of stable sinus rhythm decreased to 83% at 1-3 years and 66% at 6-8 years

Benign arrhythmias do not require treatment Supraventricular tachycardia is treated medi-cally However, it may be resistant to several drugs Some patients with bradyarrhythmias require insertion of a pacemaker

Senning Operation

The Senning operation was first performed in

1958, but it was the Mustard operation which became the operation of choice soon after its introduction in 1964 There is a possible explanation why the Mustard operation was favoured The mortality of the Senning oper-ation was high in early reports (Kirklin et al 1961) Today we know that the high mortality was due to the selection of the patients rather than to the operative technique There were several infants and young children with TGA and VSD in Kirklin's series; and some of these had pulmonary vascular obstructive disease In contrast, in Toronto, many patients with simple transposition were well palliated by a Blalock-Hanlon septectomy These children were stable and in a good condition in their second, third or fourth year of life - excellent candidates for intra-atrial repair

Brom reintroduced the Senning operation in

1975 (Quaegebeur et al 1977), and since then

it has become the intra-atrial repair of choice for most cardiac centres The idea of reviving the Senning operation was an attempt to reduce obstructive complications and arrhythmias We shall briefly review here the complications seen after the Senning operation In principle the complications are similar to those seen after the Mustard operation but are much less frequent

Systemic Venous Obstruction

In several series, sve obstruction was not

detected after the Senning operation (Parenzan

et al 1978; Quaegebeur et al 1977; Bender et

al 1980) Two sve obstructions required

reoperation in the early experience at

Birm-ingham (Kirklin and Barratt-Boyes 1986) The

Boston group (Marx et al 1983) have reported

7 obstructions in a group of 54 survivors of the

Senning operation To our knowledge, IVe

obstruction was not reported after the Senning

operation In our series of 196 Senning

oper-ations 1 patient required reoperation for sve

obstruction The obstruction was due to

techni-cal error, and reoperation was performed

within 24 h after surgery The sve and IVe

orifices were closer together than normal Both

sve and IVe pressures were elevated after

surgery At reoperation we found that the area

under the septum was narrow, thus presenting

obstruction to flow from both the sve and

IVe The diagnosis and indications for

reoper-ation are identical to those after the Mustard

operation

Pulmonary Venous Obstruction

Pulmonary venous obstruction is rare after

the Senning operation We believe that this

complication could be avoided if the technique

of Brom (Quaegebeur et al 1977) is used for

the Senning operation To our knowledge,

pulmonary venous obstruction only occurred

in patients in whom the pulmonary venous

atrium was enlarged with a patch: three patients

in the initial Birmingham experience and six

patients in the Boston series (Pacifico 1979;

Marx et al 1983) We have seen this

compli-cation in 1 patient among 196 consecutive

Senning operations; reoperation to correct the

technical error was performed within 24 h

of the original operation Pulmonary venous

obstruction did not occur in the series reported

by Parenzan et al (1978), Quaegebeur et al

(1977) and Bender et al (1980) No case of

pulmonary venous obstruction was seen in the

Green Lane Hospital series and in the recent

(1977-1984) Birmingham series (Kirklin and

Barratt-Boyes 1986) The diagnosis and the

indications for reoperation are identical to

those after the Mustard operation

Baffle Leaks

Baffle leaks are uncommon after the Senning operation This has been our experience as well as that of other authors

Tricuspid Valve Incompetence

Tricuspid valve incompetence can occur after the Senning operation Penkoske et al (1983)

has reported three mild and three severe tricuspid valve incompetences in 39 survivors

of the Senning operation and VSD closure Severe incompetence required tricuspid valve replacement in three patients The reason why tricuspid valve incompetence has been reported less frequently after the Senning operation than after the Mustard operation is probably due to the fact that the Senning operations have been performed more recently, when perhaps the techniques of bypass and myocardial protection have been improved The lower incidence of arrhythmias after recent atrial repairs may also

be attributed to this fact

Residual/Recurrent VSD and LVOTO

There are no special differences between the diagnosis and treatment of residual/recurrent VSD or L VOTO after the Senning operation and after the Mustard operation

Ventricular Function

Ventricular function has not,as yet, been extensively studied after the Senning operation However, Bender et al (1980) did not show any difference in their group of Mustards and Sennings

Arrhythmias

Parenzan et al (1978) have reported a high incidence of sinus rhythm soon after the Senning operation We have carried out a prospective study (Deanfield et al 1989),

assessing patients who underwent a Mustard

or Senning operation The standard

electrocar-diogram and 24-h Holter monitoring was

per-formed before the operation, after the

oper-ation prior to discharge from the hospital, at

1 year and at 5 years The study showed a low

incidence of active arrhythmias However,

there was a continuing decrease in the number

of patients remaining in a stable sinus rhythm

during the follow-up period No statistically

significant difference was found between the

Mustard and Senning groups

Operative Technique

Mustard

The technique of the original operation may

influence the development and the incidence

of some late complications Therefore, we shall

first describe some of the steps of the Mustard

operation which we consider important to avoid

complications

Primary Operation

1 SVC Cannulation The sve is usually

can-nulated directly through a purse-string suture

This suture is placed at least 10 mm above the

CORRECT

INCORRECT Fig 14.1

Fig 14.2

sinus node to avoid its injury The purse-string

is oblong (Fig 14.1) rather than circular to avoid narrowing of the sve when the purse-string is tied after the sve cannula is removed Alternatively, the purse-string is not tied after decannulation but the partial occlusion clamp

is applied on the cava and an incision in the sve is formally closed with a fine polypropy-lene stitch (Fig 14.2a, b) We favour the technique of an oblong purse-string which is tied after decannulation

2 Shape and Material used for Baffle The shape and the material of the baffle and the technique of its insertion may contribute to the development of obstruction It is important to construct the sve pathway in such a manner that the baffle forms less than 50% of its circumference If at least 50% of the pathway

is constructed of the atrial wall, obstruction is unlikely to develop if the patch does not grow,

or even if it shrinks (Fig 14.3)

In our early experience both the material used for the baffle and the shape of the baffle played an important role (Stark et al 1980)

We found that a redundant , thin Dacron patch had a tendency to fold upon itself (Fig 14.4a) Apposition of platelets and fibrin and subsequent fibrosis of this tissue led to severe thickening of the patch (Fig 14.4b, c) Brom has suggested cutting the patch into a

"trouser shape" (Quagebeur and Brom 1978)

He constructed the patch on the basis of measurements of sve and IVe circumference

' -Baffle

Fig 14.3

(distances E-D and D-F in Fig 14.5a) and the

distance between the edge of the intra-atrial

septum and the pulmonary veins (C-D in Fig

14.5a) Subsequently, good results have been

achieved with this patch irrespective of whether

it was tailored from Dacron or pericardium

The Toronto group has always used

pericar-dium The original large quadrangular patch

of the Mustard operation has been only slightly

modified (Trusler et al 1980) (Fig 14.5b)

Barratt-Boyes uses a small patch His concept

3 Thrombosis Thrombosis may cause SVC

pathway obstruction, especially if the lumen was already compromised by a faulty operative technique Insertion of several central venous cannulae into the internal jugular vein may be another cause This may be of particular importance in young infants Infusion of plate-lets and/or hypertonic solutions through these lines may be another contributing factor

It is useful to evaluate the adequacy of the SVC pathway soon after the operation by Doppler echocardiography or by an injection

of contrast media through an internal jugular line and performing a chest radiograph at the same time Both these techniques are useful and can be easily performed in the intensive care unit The diagnosis of even mild SVC pathway narrowing would alert us to avoid infusions of hypertonic solutions Under such circumstances, it may be safer to remove the jugular vein cannula and place it elsewhere

4 Inadequate Resection of Intra-atrial tum Inadequate resection of the intra-atrial

Sep-septum may leave a ridge of tissue which then causes turbulence and contributes to the

A B

a

Fig 14.5

Fig 14.6

development of obstruction On the other

hand, too extensive resection may damage the

sinus node artery and lead to arrhythmias

(Trusler et al 1980) If one avoids an extensive

resection, it is possible to use the superior part

of the atrial septum as a flap, which is then

sutured to the baffle (Turley and Ebert 1978)

This step is illustrated in Fig 14.6

5 Coronary Sinus Cut-back Opening the

cor-onary sinus deep into the left atrium ensures

a wide IYC pathway Although it has been

suggested (Ebert et al 1974) that this

Coronary sinus

Fig 14.7

manoeuvre may cause arrhythmias, it has not been confirmed by others (Clarkson et al 1976) We have not cut the coronary sinus routinely; however, we find the technique very useful in children in whom the distance between the SYC and IYC orifices is short The suture line from the left to the right pulmonary veins should diverge to avoid pulmonary venous obstruction This may, on the other hand, compromise the IYC pathway; therefore , under such circumstances we prefer to open the coronary sinus deep into the left atrium (Fig 14.7) It is important to open the coronary sinus with one cut Repeated, short cuts may catch the fold in the atrial wall and cut outside the heart This does not cause problems if recognised in time It is very difficult to control the bleeding from the posterior part of the left atrium without the aid of cardiopulmonary bypass Therefore, we routinely lift the heart

up before discontinuing perfusion to check for any damage to this area

7 Width of the Baffle Too redundant a baffle may form adhesions with the lateral atrial wall and cause pulmonary venous obstruction We assess the width of the patch during insertion When the suture line around the left pulmonary veins and towards the right upper and lower pulmonary veins has been completed we hold the opposite edge of the patch with forceps and keep it close to the cut edge of the atrial septum A curved instrument then pushes the patch from behind towards the lateral atrial wall (Fig 14.8) If the patch reaches the atrial wall it is too redundant and should be trimmed

8 Placement of the Baffle The correct ment of the baffle is important to avoid either systemic or pulmonary venous obstruction Concern about one of these complications may cause the other one The suture line from the left pulmonary veins should diverge upwards between the SYC and right pulmonary vein Inferiorly, the suture line runs from the left pulmonary veins to between the right lower pulmonary vein and the orifice of the lYe Figure 14.9 illustrates the correct and incorrect placement of a baffle

place-9 Incision in the Right Atrium and Enlargement

of the Pulmonary Venous Atrium Various

CORRECT

Fig 14.8

incisions in the right atrium have been suggested for the Mustard operation We believe that it

is not important which type of incision is used

if the pulmonary venous atrium is subsequently enlarged Insertion of a generous baffle would ensure large systemic venous pathways but

it may compromise the pulmonary venous pathway It is probably safer to enlarge the pulmonary venous atrium, especially if the operation is performed in small infants Enlargement can be performed with a patch Alternatively, a v-Y incision in the atrium advances the flap of the atrial wall between the right upper and lower pulmonary veins, thus preventing narrowing at a crucial point of the pulmonary venous pathway This technique

is used by Boyes (Kirklin and Boyes 1986) (Fig 14.10)

Barratt-Reoperations

1 Approach We prefer to approach the heart through a right anterolateral thoracotomy for most reoperations after the Mustard operation (Szarnicki et al 1978) A right thoracotomy offers several advantages over the sternotomy approach As the pericardium is usually used for the baffle the anterior part of the right ventricle may be adherent to the back of the sternum With a right thoracotomy, dissection

of the right ventricle is not required, thereby avoiding potential InJunes to structures obscured by adhesions from the first operation INCORRECT Tn the presence of sve obstruction, high-

Fig 14.9 pressure venous collaterals may cause

consider-able bleeding during sternal re-entry These likewise are avoided with a thoracotomy In addition, a right chest approach places the sve and Ive closer to the surgeon than from the front, making dissection and cannulation easier Reoperations performed for sve, IVe, or pulmonary venous obstruction, baffle leak, tricuspid valve incompetence or residual/recur-rent VSD are best performed through a right atriotomy The aorta is usually located anteri-orly and to the right in patients with TGA; therefore its dissection and cannulation is easy from the right chest as well

Reconstruction of the left pulmonary artery

or insertion of a left ventricular to pulmonary Fig 14.10 artery conduit cannot be performed through a

Fig 14.11

right thoracotomy For these reoperations, we

use either a median sternotomy or a left

thoracotomy (see Chapter 20, pp 283-284) Other

authors prefer a standard approach using

sternal re-entry for all operations after Mustard

or Senning procedures (Kron et al 1985;

Kirklin and Barratt-Boyes 1986)

For a right thoracotomy approach, the

pati-ent is placed on the operating table at about

50° (Fig 14.11) An external defibrillator

electrode is placed between the patient's

scapu-lae One groin is prepped for cannulation of

the femoral/iliac vessels should it be difficult

to reach the aorta The right thoracotomy is

usually performed through the fifth intercostal

space This gives adequate access both to the

aorta and to the IVe The sternum is often

transected Extension of the thoracotomy

post-eriorly on the right side is usually minimal, so,

in effect, it remains an anterior thoracotomy

2 Cannulation The edge of the pericardium

is identified Care is taken during the dissection

not to injure the phrenic nerve It is easy

to avoid a phrenic nerve injury from the

thoracotomy approach because of the proximity

of the phrenic nerve to the surgeon A

purse-string suture is then placed on the ascending

aorta and on the pulmonary venous atrium

close to the atrioventricular junction (Fig

14.12) If any bleeding occurs during the

subsequent dissection, bypass can be initiated

after cannulating the aorta and the pulmonary

venous atrium with a single venous cannula

SVC and IVC purse-strings are placed The

dissection around the SVC is easy; dissection

'Fig 14.12

around the IVC is usually delayed until pulmonary bypass is started Perfusion is started with a cold perfusate (20-25 0c) When the heart fibrillates, the pulmonary venous atrium

cardio-is opened and caval snares are tightened Myocardial protection is achieved either by cold perfusion with the heart fibrillating or aortic cross-clamping with cardioplegia We favour cross-clamping of the aorta with cardio-plegia for the initial stages of the operation Care is taken to keep the time of the cross-clamping to a minimum; the operation may therefore be completed on a cold fibrillating heart If the pulmonary venous atrium was not cannulated for perfusion, a sump sucker is introduced through the purse-string into the pulmonary venous atrium or through the tricus-pi<;l valve into the right ventricle

3 Systemic Venous Obstruction If the SVC pathway is obstructed, a longitudinal cut is made into the SVC pathway close to the atrial septum (Fig 14.13) The pathway should be free at this point The obstructed area is inspected from below and the incision in the roof of the pathway is extended Care is taken not to injure the area of the sinus node artery Any thrombus present is removed If the pathway is completely obstructed it may be helpful to pass a probe or a curved instrument through a stab wound in the SVc This identifies the point of entry of the SVC into the intracardiac SVC channel, and an opening from below can be made easily If the baffle

is narrow but thin and pliable it is possible to suture a patch into the incision in the pathway

is not severely compromised at the time of reoperation We believe it is safer under such circumstances to replace the whole baffle because the future growth of the child and the lack of growth of the baffle may gradually restrict the lye channel

If the whole baffle has to be replaced (Fig

14.15), we use either Gore-Tex or a patch tailored from a tube of woven Dacron or double-velour knitted Dacron (insert to Fig

14.15) We have successfully used woven Dacron for the new baffle but, in view of the propensity to form thicker and loosely attached neo-intima, we would currently prefer a Gore-Tex patch or a double-velour knitted patch

It may be difficult to suture the new patch

if the entire baffle is removed Deep stitches

in the area of the atrial septum close to the tricuspid valve may damage the conduction mechanism For this reason we leave a narrow rim of the old baffle in place; the new baffle

is then sutured to this rim

When the new patch has been sewn in place, the decision must be made as to whether the pulmonary venous atrium is to be enlarged In general we prefer to enlarge it at the time of any reoperation after a Mustard operation, except in patients with tricuspid valve incompet-ence In such patients, the pulmonary venous atrium is already considerably enlarged and a patch is not required In all other patients, we think it is advantageous to close the atrium with a patch Both the previous surgery and ,the reoperation will leave scars on the atria, thus possibly impairing future growth The atrial incision is extended down between the right upper and lower pulmonary veins A large Gore-Tex patch is sutured in place with a 4-0

or 5-0 polypropylene suture (Fig 14.16) After the first stitches on the patch have been placed, it is possible to remove the aortic clamp or, if the heart fibrillates , to defibrillate

it and to start rewarming Great care must be taken to avoid air embolisation as the heart was not freed from adhesions We place the

Fig 14.16

patient in a mild Trendelenburg position,

and the atrial sump is advanced through the

tricuspid valve to the right ventricle to keep

the valve incompetent and to decompress the

right ventricle The perfusion pressure is kept

high so as not to allow the aortic valve to open

When the atrium is closed caval snares are

released An aortic needle vent is put on

suction, the aorta cross-clamped between the

cannula and the vent, and a sump sucker pulled

from the right ventricle to the pulmonary

venous atrium and then removed The pressure

in the pulmonary venous atrium is raised to

5-7 mmHg, and the anaesthetist starts inflating

the lungs The de-airing procedure is repeated

a few times When the patient is completely

rewarmed, the perfusion is discontinued in the

usual manner The cannulae are removed from

the heart and protamine is given A fine

polyethylene catheter is left in the pulmonary

venous atrium for pressure monitoring; atrial

and ventricular pacemaker wires are placed

and two chest drains inserted The thoracotomy

is closed in the usual manner

4 Pulmonary Venous Obstruction The

app-roach is the same as that described for systemic

venous obstruction On cardiopulmonary

bypass the aorta is cross-clamped and

cardiople-gia is given The pulmonary venous atrium is

widely opened from the atrioventricular groove

A small opening from the posterior part of the

pulmonary venous atrium is visualised (arrow

in Fig 14.17) The incision in the atrium is

then extended through this opening to a point

between the right upper and right lower

Fig 14.17

pulmonary veins If necessary, it is further extended into the posterior wall of the left atrium (Fig 14.18a) A large Gore-Tex patch

is sutured into this incision in a fashion similar

to that described for closure of the pulmonary venous atrium after the repair of systemic venous obstruction (Fig 14.18b) Rewarming, discontinuation of perfusion and closure of the thoracotomy are then performed in the usual manner

5 Tricuspid Valve Incompetence The roach, cannulation, perfusion and myocardial preservations are the same as described for reoperations for systemic venous obstruction The tricuspid valve is carefully inspected to

app-a

Fig 14.18

assess the pathology The valve can rarely be

repaired (Park et al 1983) If the valve is

severely incompetent, it is usually replaced

We have replaced the tricuspid valve in 6

patients in our series of 563 Mustard operations;

Penkoske et al (1983) has reported 3 patients

with severe tricuspid incompetence, all of

whom required valve replacement

The choice of valve prosthesis is limited

Heterografts calcify early in children We do

not have any experience with the stent-mounted

aortic or pulmonary homografts which have

been used in adult patients in the tricuspid

position by Boyes (Kirklin and

Barratt-Boyes 1986) In our patients, we have used

Bjork-Shiley valves, as do the Boston group

(Penkoske et al 1983) Excellent results using

the St Jude medical valve have been reported

in the tricuspid position by Singh et al (1984)

We have used either interrupted mattress

sutures with pledgets or a running stitch for

the valve insertion The technical details are

discussed in Chapter 24 (see p 345)

6 Baffle Leaks There are no special technical

"tricks" for repair of baffle leaks When the

atrium is opened the whole baffle is carefully

inspected Small leaks are closed directly, the

large ones with a patch of pericardium,

Gore-Tex or Dacron If systemic or pulmonary

venous obstruction is also present, we use

the technique as described for these two

complications Reoperations for an isolated

large residual shunt (not associated with other

defects) is easy The perfusate is cooled to

30 DC, the aorta is cross-clamped, and the

defect in the baffle is closed with a patch

7 Residual/Recurrent VSD Most residual!

recurrent VSDs can be closed through the

tricuspid valve; therefore a right thoracotomy

is, again, our approach of choice VSDs located

near the apex and multiple VSDs are best

approached from a midline sternotomy because

a left ventriculotomy or an apical fish-mouth

incision may be required for their closure The

technical aspects of the repair of residual/

recurrent VSDs are discussed in Chapter 12

(see pp 165-168)

8 Residual/Recurrent LVOTO Detailed

pre-operative assessment, as discussed earlier in

this chapter (see p 191) is very important for the choice of the best approach Repeated attempts

to relieve L VOTO are successful only in patients with favourable anatomy More often, symptomatic L VOTO has to be bypassed with

a v.alved conduit placed between the apex of the left ventricle and the main and/or left pulmonary artery This operation can con-veniently be performed through a left thora-cotomy Details of the operative technique are described in Chapter 20 (see pp 283-284)

9 Right Ventricular Dysfunction Until cently only medical treatment was offered

re-to patients with systemic (right) ventricular dysfunction Mee (1986) has suggested and successfully performed pulmonary artery band-ing followed by an arterial switch operation in five patients The details of this approach are discussed in Chapter 16 (see p 217)

10 Arrhythmias Some arrhythmias do not require treatment; tachyarrhythmias are treated medically Patients with sick sinus syndrome are considered for insertion of a pacemaker if they have Stokes-Adam syndrome or severe bradycardia (less than 30 40 beats/min) Pati-ents with diminished R V function associated with bradycardia may also benefit from pacing (see Chap 6, p 68)

Senning

Obstructive complications after the Senning operation are uncommon As with the Mustard operation, the technique of the original oper-ation may influence the incidence of obstruc-tion Some of the important technical details

of the Senning operation will therefore be described first

Primary Repair

All the details of SVC cannulation in the Mustard operation also apply for the Senning operation (see Figs 14.1, 14.2) The intracar-diac part of the SVC channel may be con-structed too narrow if the right atrial incision

is too close to the crista terminalis (Fig 14.19)

CORRECT

INCORRECT

Fig 14.19

This may result in not enough lateral atrial flap

being available for the roof of the SVC channel

The SVC pressure may be elevated for a few

hours after the operation but it usually regresses

quickly Severe obstruction is rare As the SVC

pathway is made entirely from the patient's

own atrial tissue it grows with the patient

The area under the septum may be narrow

in some patients and does not allow free SVC

and IVC flow This area may be enlarged by

opening the coronary sinus into the left atrium

We now use the coronary sinus cut-back more

frequently; others use it routinely (Kirklin and

Barratt-Boyes 1986)

Enlargement of the septal flap with a piece

of pericardium or Dacron is used in patients

with a large ASD to make up the deficient

atrial septal tissue The patch should only

enlarge the width but not the length of the flap

(Fig 14.20) If the length is increased, the flap

may subsequently bulge into the pulmonary

venous atrium and possibly cause pulmonary

venous obstruction With more experience it is

usually possible to use the tissue in the fossa

ovalis (Fig 14.21a) or to augment the septal

flap with the flap created by the cut-back of

the coronary sinus without using any additional

patch (Fig 14.21b,c) Alternatively, the narrow

atrial flap may be split and opened to increase

the width (Fig 14.21d)

Pulmonary venous obstruction has been

described in patients in whom the pulmonary

venous atrium was enlarged with a patch (Otero

Co to et al 1979; Pacifico 1979) (Fig 14.22) Using the atriotomy with cut-backs in the superior and inferior corners of the incision provides enough tissue to suture the medial atrial flap across the SVC and IVC and around the pulmonary veins We have not used a patch

c Fig 14.21

INCORRECT Fig 14.22

to enlarge the pulmonary venous atrium in any

of our 196 Senning operations When the

medial a~rial flap does not easily reach towards

the pulmonary veins, the pulmonary venous

atrium can be enlarged by suturing it to in situ

pericardium, as suggested by Senning (1975)

(Figs 14.23, 14.24)

Reoperations

1 Approach Early reoperation is performed

through a median sternotomy We have not

Fig 14.24

had to reoperate late after the Senning ation;, we would use a right thoracotomy as for reoperations after the Mustard operation The sve and Ive are cannulated If sve obstruction is the only lesion, enlargement of the medial part of the pathway can be perfor-med on a beating heart using moderate hypo-thermia However, aortic cross-clamping with cardioplegia is required for obstructions repaired from within the pulmonary venous atrium, obstruction of the pulmonary venous pathway, operations on the tricuspid valve, LVOTO or a VSD Reoperations in infants may be performed using deep hypothermia and circulatory arrest with a single venous cannula inserted into the base of the pulmonary venous atrium

oper-2 Systemic Venous Obstruction Our ence with systemic venous obstruction is limited

experi-to one early reoperation performed within 24 h

of the original surgery We used a midline sternotomy, aortic and bicaval cannulation and aortic cross-clamping with cardioplegia The heart was opened through an incision in the pulmonary venous atrium close to the atrioventricular groove (Fig 14.25a) The advantage of this incision is that the medial atrial flap does not have to be detached from the sve and the right pulmonary veins It also obviates the need for repeat suturing across the area of the sinus mode The sve channel

Fig 14.25

is easily visualised from within the pulmonary

venous atrium (Fig 14.25b) Part of the suture

line attaching the flap to the atrial septum is

removed This detaches the sve pathway roof

(Fig 14.26a) ; the size of the channel is assessed

Then an oval piece of pericardium is sutured

into this opening, either over the sve only

A longitudinal incision is made and the extent

of the obstruction assessed The incision may

be facilitated by the placement of a probe or

a curved instrument through the stab wound

in the sve into the intracardiac portion of the pathway An oval patch of pericardium or Gore-Tex is then sutured into this incision We have not used this technique; however, it should be easy and could be performed without aortic cross-clamping The disadvantage of this technique is possible injury to the sinus node artery which may be located in the area of the incision It may be difficult to see the artery

in adhesions at reoperation

3 Pulmonary Venous Obstruction We have seen pulmonary venous obstruction in one patient immediately after the Senning oper-ation It was due to a technical error, and reoperation was performed a few hours after the original surgery The pulmonary venous atrium was opened close and parallel to the atrioventricular groove and an oval patch of pericardium was sutured into this incision

b

Should late pulmonary venous obstruction develop, it could be treated with the same technique as described for pulmonary venous Fig 14.26 obstruction after the Mustard operation (see

Figs 14.17, 14.18) The pulmonary venous

atrium can be enlarged by suturing it to in

situ pericardium (M Turina 1986, personal

communication) (see Figs 14.23, 14.24)

4 Other Complications The operative

tech-nique for tricuspid valve incompetence, baffle

leaks, residual/recurrent VSD or L VOTO does

not differ from the technique used for these

complications after the Mustard operation

Results of Reoperations After

Mustard or Senning Procedures

The mortality rate after reoperations for

obstructive complications is not insignificant,

especially if the operation is delayed until the

patient is very ill (Kirklin and Barratt-Boyes

1986)

Reoperation for systemic venous obstruction

was required in 45 children in a combined

experience of Stark et al (1974), Park et al

(1983), Marx et al (1983) and Kron et al

(1985) Eleven patients (24%) died

Reoperation for pulmonary venous

obstruc-tion, either complete or incomplete (left

pul-monary veins only), was reported (Driscoll et

al 1977; Oelert et al 1977; Trusler et al 1980;

Park et al 1983; Marx et al 1983; J Stark

1987, unpublished work) in 46 children; 10

died (22%) It is not easy to estimate the exact

incidence and risk of reoperation for pulmonary

and/or systemic venous obstruction In some

reported series, patients died before

reoper-ation or refused surgery Some symptomatic

patients were lost to follow-up

The recurrence of obstruction is uncommon;

it was reported in ten patients from six

institutions (Venables et al 1974; Hagler et al

1978; Marx et al 1983; Park et al 1983; Kirklin

and Barratt-Boyes 1986) We have performed

second and third reoperations in one patient

each Both survived

The risk of tricuspid valve replacement after

the Mustard or Senning operation is difficult

to estimate because of the small number of

reported reoperations We have replaced the

tricuspid valve in six children after Mustard or

Senning operations Four survived and are well

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of the great arteries: indications for and results of operation

in 32 patients Circulation 43: 738-747 Wyse RKH, Haworth SG, Taylor JFN, Macartney FJ (1979) Obstruction of superior vena caval pathway after Mustard's repair Reliable diagnosis by transcutaneous Doppler ultra- sound Br Heart J 42: 162-167

Reoperations After Arterial Switch Operation

A.R Castaneda

Introduction

The initial high operative mortality reported

with the arterial switch operation for repair of

complex forms of transposition of the great

arteries (TGA) has now been reduced

signifi-cantly The rather steep learning curve

associ-ated with the early development of this

oper-ation was caused, in part, by technical

difficulties related to the transfer of the

coron-ary arteries and also by patient selection Jatene

realised that in patients with TGA and an

intact ventricular septum the left ventricle

would soon adapt to the low resistance of the

pulmonary circuit and thus be unable to

function when faced with systemic resistance

(Jatene et al 1976) Therefore, in his initial

experience, Jatene limited the arterial switch

operation to patients with TGA and either a

large ventricular septal defect (VSD) or with

haemodynamically significant left ventricular

outflow tract obstruction (L VOTO) However,

some of these patients had already developed

pulmonary vascular obstructive lesions or

others had significant organic LVOTO By

now, the operative mortality for patients with

both simple and complex forms of TGA

(induding neonates) has been reduced to as

low as 0%-12% (Castaneda et al 1984; Smith and Yacoub 1984; Idriss et al 1985;

Radley-Quaegebeur et al 1986) This improvement has occurred mostly because of stricter selection criteria and a better understanding of both the time-related functional and anatomical changes

of the left ventricle and of the variable anatomy ofthe coronary arteries in TGA Consequently,

in many institutions the arterial switch ation has become the operation of choice for children with both simple and complex forms

oper-of TGA Encouraging late (1 year) clinical and haemodynamic postoperative results have also been reported (Gibbs et al 1986; Hausdorf

2 Systemic semilunar valve (anatomical monary valve) insufficiency

pul-3 Failure of the left ventricle to maintain

long-term function after correction

Because of the relative newness of this

oper-ation many of these questions still remain

unanswered However, experience so far

indi-cates that most of these possible complications

have not occurred Only very few patients who

had postoperative cardiac catheterisation after

arterial switch operation have developed

sten-osis or obstruction of the transferred coronary

arteries Of 43 patients who underwent cardiac

catheterisation and cineangiography one year

after a successful arterial switch operation at

the Children's Hospital, Boston, 2 had proximal

occlusion of the left anterior descending

coron-ary artery with excellent retrograde perfusion;

both patients had a dominant right coronary

artery system, with a large circumflex coronary

artery originating from the right coronary artery

and a very small anterior descending coronary

artery Both patients are asymptomatic

Sys-temic semilunar valve regurgitation has been

recognised after arterial switch operation,

per-haps more so in patients who had a previous

pulmonary artery band placed (Yacoub et al

1982; Gibbs et al 1986) Martin et al (1988a)

reported neo-aortic valve incompetence in 45%

of 55 children who had an aortogram 4 56

months after arterial switch operation

How-ever, it was trivial in all but 1 patient

All patients have normal left ventricular

function and virtually none have had atrial

arrhythmias (Arensman et al 1983; Helgason

et al 1985) Haemodynamic studies of the

above-mentioned 43 patients 1 year after

arterial switch operation, revealed the following

Five patients had trivial aortic regurgitation

In 28 patients with adequate two-dimensional

echocardiograms, regional wall motion analysis

using frame-by-frame computer digitalisation

of long and short axis views of the left ventricle showed no differences from age-matched con-trols Systolic wall stress, fractional shortening and rate-corrected velocity of shortening and a load independent index of contractility (ESWS/ VCFc) were also normal in 27 of the 28 patients studied In patients with serial contractility studies, two had depressed contractility 7 days after surgery, with return to normal by 6 months The only complication of consequence has been stenosis at the pulmonary artery anastomosis (Yacoub et al 1982; Helgason

et al 1985; Sidi et al 1987) Supravalvar pulmonary stenosis with a gradient of greater than 35 mmHg occurred in nine of our patients; five required reoperation after unsucccessful balloon angioplasty In all of these patients excessive tension on the anastomosis led to elongation and flattening of the anteriorly translocated main pulmonary artery Late pul-monary artery stenosis has also been reported

in patients who had conduits interposed between the proximal aorta (neopulmonary artery) and the distal main pulmonary artery (Yacoub et al 1982) Kanter et al (1985) reported that 9 of 13 patients (69% ) at late postoperative catheterisation had pressure gradients ranging from 27 to 70 mmHg (mean

45 mmHg) across the right ventricular outflow tract which had been clinically undetected In six of their nine patients the gradient was supravalvar and of the remaining three patients with infundibular gradients all had a side-by-side relationship ofthe great arteries Subvalvar right ventricular outflow tract obstruction was also observed intraoperatively by these authors

in five patients, three of whom died from these complications So far, none of our patients with an anteroposterior, oblique or side-by-side relationship of the great arteries has demonstrated such gradients

Recently, Muster et al (1987) reported haemodynamically significant kinking of the proximal aortic arch after a Lecompte manoeuvre in patients with either a previously repaired coarctation and/or with a mild unre-paired coarctation The degree of "neocoarc-tation" seemed to be mostly related to the degree of pre-existing aortic arch hypoplasia Martin et al (1988b) reported significant pul-monary stenosis (RV/LV ratio> 0.5) in 23 of

Fig 15.1

their 66 restudied patients (35%) The

inci-dence was higher in patients operated upon as

neonates (41%) Norwood (1988) has reported

reoperations in 16 of 110 survivors of arterial

switch operation (6%-13% for pulmonary

stenosis) As the incidence varies widely, it is

most probably caused by different operative

techniques and, therefore, could be reduced

Severe subvalvar obstruction of the left

ven-tricular outflow tract was seen by one of the

editors (J S) 4 years after the operation (Fig

Transfer of Coronary Arteries from the Ascending Aorta and Reimplantation into Proximal Neo-aorta

The ascending aorta is transected mately 10 mm distal to the origin of the coronary arteries (Fig 15.2a) The left and right coronary arteries are then removed with

approxi-a lapproxi-arge cuff of the approxi-aortic wapproxi-all (Fig 15.2b) The incision extends from the free edge of the transected proximal aorta to the bottom of the corresponding aortic sinus The coronary arteries are not dissected or otherwise manipu-latedbeforehand; if additional length is needed for the aortocoronary flap to reach the neo-aorta, minimal dissection of the most proximal part of the coronary arteries is done after

d

Fig 15.2

explantation The pulmonary artery is then

transected proximal to its bifurcation The

distal pulmonary artery is brought anterior to

the ascending aorta (Lecompte manoeuvre)

(Lecompte et al 1981) Wedge-shaped

seg-ments corresponding to the implantation site

of the coronary arteries are cut out with

scissors, starting at the free border of the

transected proximal pulmonary artery

(neo-aorta) However, these excisions must not

extend deeply into the sinus because this

increases the distance across which the

mobil-ised coronary artery must reach; downward

displacement of either the transferred left or

right coronary arteries can cause a kink and

interfere with coronary perfusion The coronary

artery flaps are then sewn into the neo-aorta

with a continuous 7-0 monofilament suture

(Fig 15.2c,d) Because of the relatively

com-mon variations in the origin and course of the

coronary arteries, the techniques for coronary

artery transfer mus~ be adjusted to suit each

individual case For example, if the circumflex

coronary artery arises from the right cor()nary

artery (second most common coronary artery

pattern), the site of implantation into the

neo-aorta is kept slightly higher to avoid kinking

of the circumflex coronary artery Occasionally,

coronary artery transfer can prove more

diffi-cult in a single left-sided origin or when the

aortopulmonary artery relationship is

side-by-side rather than anteroposterior If, during

transfer and/or anastomosis the coronary artery

suffers undue rotation or kinking, the

anasto-mosis must be undone and the abnormality

corrected Occasionally, a segment of

pericar-dium pretreated with 0.6% gluteraldehyde can

be useful in eliminating excess tension or in

facilitating alignment of a rotated coronary

artery

Excess aortic wall tissue which extends

beyond the rim of the neo-aorta is helpful

in tailoring the aortic anastomosis and is

particularly useful in compensating for size

discrepancies between the very large proximal

neo-aorta and the much smaller distal aorta,

as is typically the case in older children with

TGA and VSD The aortic anastomosis is

carried out with a continuous 6-0 monofilament

suture

To reduce tension on the pulmonary artery

anastomosis it is important to first separate the

ascending aorta completely from the main pulmonary artery The ductus arteriosus is divided between sutures, and the branches of the right and left pulmonary arteries are freed

of surrounding tissue and must be mobilised well into the hilus to the point where the intraparenchymal branches become clearly vis-ible This extensive dissection and mobilisation

of the branch pulmonary arteries greatly tates the Lecompte manoeuvre (Lecompte et

facili-al 1981) Although we have successfully used the Lecompte manoeuvre in a few patients with side-by-side relationships of the great arteries and very mobile pulmonary arteries, generally it is advisable to leave the pulmonary artery in situ in these conditions to avoid compression of the right coronary artery anasto-mosis

The coronary donor sites in the proximal neopulmonary artery are filled with autologous pericardial patches (fixed for 10 min in 0.6% gluteraldehyde) (Fig 15.3a) These pericardial patches fulfil two purposes:

1 To decrease the distance which the distal pulmonary artery has to reach for anasto-mosis with the neopulmonary artery

c Fig 15.3

2 To aid in enlarging the circumference of

the neopulmonary artery, facilitating the

anastomosis between the usually much

larger distal pulmonary artery and narrower

neopulmonary artery

The anastomosis is begun at the posterior

commissure using a continuous ~

monofila-ment suture The posterior and lateral parts of

the distal pulmonary artery are sutured to the

free edge of the pericardial patch (Fig 15.3b)

while the anterior part of the anastomosis

includes the remaining portion of the original

aortic wall and the distal pulmonary artery

(Fig 15.3c)

As described earlier, the development of

late haemodynamically significant obstruction

across the pulmonary artery anastomosis in our

patients occurred because of excessive tension

on the suture line In two patients this was

caused by direct anastomosis of the distal

pulmonary artery to the neopulmonary artery

without filling the explanted areas with peri

car-dial patches In the other three patients we felt

that inadequate dissection and mobilisation of

the pulmonary artery branches was the principal

cause of the obstruction These patients

developed suprasystemic right ventricular

pressures between 6 and 9 months after the

arterial switch operation Additional

infor-mation about the surgical technique of arterial

switch operation is given in Chapter 16

Diagnosis and Indications for Reoperation

The diagnosis of postoperative supravalvar

pulmonary stenosis is suggested by a loud,

harsh, pan systolic murmur heard at the base

of the heart Significant systolic gradients ate

frequently accompanied by a systolic precordial

thrill Because of the location of the neo-aorta

and neopulmonary artery, it may be difficult to

distinguish, by physical examination, between

supravalvar pulmonary stenosis and supravalvar

aortic stenosis

With significant supravalvar pulmonary

sten-osis right ventricular hypertrophy is uniformly

present on the surface electrocardiogram

Two-dimensional echocardiography provides an

additional non-invasive means of assessment;

the ventricular septum is flat in systole, the

Fig 15.4

anastomosis may appear narrowed and elevated flow velocities may be detected by Doppler The diagnosis should be confirmed by cardiac catheterisation and angiography (Fig 15.4)

We advise repair of the supravalvar pulmonary stenosis in the presence of systemic or suprasy-stemic pressures in the right ventricle

Reoperation

Reoperation for Relief of Supravalvar Pulmonary Artery Stenosis After Arterial Switch Operation

The mediastinum is entered through the vious midline sternotomy A small area of right atrial appendage is freed from adhesions Similarly, the most distal segment of the ascending aorta, an area limited proximally by the pulmonary artery and distally by the innominate vein, is exposed The main pulmon-ary artery anastomosis was found to be clearly under tension and appeared flattened Cardio-pulmonary bypass is begun through a single right atrial venous return line and a distal aortic cannula (Fig 15.5) On partial cardiopulmon-ary bypass (30°C) a longitudinal incision is made into the main pulmonary artery, exposing

pre-a slit-like lumen (Fig 15.6pre-a) None of the patients had cicatricial narrowing of the anasto-mosis A diamond-shaped Gore-Tex patch is tailored to the configuration of the widened

Ao PA

Fig 15.5

inclSlon and sewn into the main pulmonary

artery using a 6-0 continuous Gore-Tex suture

(Fig 15.6b)

Fig 15.6

Editor's Note A patient who developed late

LVOTO (see Fig 15.1) underwent reoperation 4 years

after arterial switch operation Bypass was established

by high aortic and right atrial cannulation The

pulmonary artery was then transected (Fig 15.7a) and

the origin of the transferred coronaries carefully

identified The aorta was cross-clamped , cardioplegia

was given and the aorta was opened obliquely

(Fig 15.7b) The subvalvar fibrous shelf was identified

and enucleated with a Watson-Cheyne dissector (Fig

15.7c) This patient made an uncomplicated recovery

on Doppler studies, although in one patient there was an increase in velocity of flow through the right ventricular outflow tract

In conclusion, the arterial switch operation for repair of simple and complex forms of TGA can now be accomplished even in the neonate

at a low operative risk The coronary, aortic and pulmonary artery anastomoses seem to grow normally The few instances of late supravalvar pulmonary stenosis, which occurred mostly early in the Harvard experi-ence, seemed to be principally due to technical factors This complication should therefore be avoidable Percutaneous balloon dilatation of the pulmonary artery stenoses proved ineffec-

tive, but reoperation for relief of the

supraval-var pulmonary stenosis was uniformly

success-ful The left ventricular function measured 1

year after arterial switch operation was normal

in all patients

References

Arensman FW, Bostock 1, Radley-Smith R, Yacoub MH

(1983) Cardiac rhythm and conduction before and after

anatomic correction of transposition of the great arteries

Am J Cardiol 52: 836-839

Castaneda AR, Norwood WI, Lang P, Sanders SP (1984)

Transposition of the great arteries and intact ventricular

septum: anatomical repair in the neonate Ann Thorac

Surg 38: 438-443

Gibbs JL, Qureshi SA, Grieve L, Webb C, Radley-Smith

R, Yacoub MH (1986) Doppler echocardiography after

anatomical correction of transposition of the great arteries

Br Heart J 56: 67-72

Hausdorf G, Gravinghoff L, Sieg K, Keck EW, Radley-Smith

R, Yacoub MH (1985) Left ventricular performance after

anatomic correction of d-transposition of the great arteries

J Am Coli Cardiol 5: 479 (abstract)

Helgason H, Hougen TJ, Jacobs M et al (1985) Hemodynamic

results of primary anatomic repair of transposition of the

great arteries In: Doyle EF, Engle MA, Gersony WM,

Rashkind WI, Talner NS (eds) Paediatric cardiology:

proceedings of the Second World Congress of Cardiology

Springer, New York, pp 558-561

Idriss FS, Albanic MN, DeLeon SY et al (1985) Transposition

of the great arteries with intact ventricular septum: arterial

switches in the first month of life 1 Am Coli Cardiol 5:

477 (abstract)

latene AD, Fontes VF, Paulista PP et al (1976) Anatomic correction of transposition of the great vessels 1 Thorac Cardiovasc Surg 72: 364-370

Kanter KR, Anderson RH, Lincoln C, Rigby ML, bourne EA (1985) Anatomic correction for complete transposition and double-outlet right ventricle J Thorac Cardiovasc Surg 90: 690-699

Shine-Lecompte Y, Zannini L, Hazan E et al (1981) Anatomic correction 'of transposition of the great arteries J Thorac Cardiovasc Surg 92: 629-631

Martin RP, Ladusans EJ, Parsons 1M, Keck E, Smith R, Yacoub MH (1988a) Incidence, importance and determinants of aortic regurgitation after anatomical correction of transposition of the great arteries Br Heart

Radley-J 59: 120-121 Martin RP, Ladusans EJ, Parsons 1M, Keck E, Radley-Smith

R, Yacoub MH (1988b) Incidence and site of pulmonary stenosis after anatomical correction of transposition of the great arteries Br Heart 1 59: 122-123

Muster AJ, Berry TE, I1bawi MN, DeLeon SY, Idriss FS (1987) Development of neo-coarctation in patients with transposed great arteries and hypoplastic aortic arch after Lecompte modification of anatomical correction 1 Thorac Cardiovasc Surg 93: 276-280

Norwood WI (1988) Arterial switch Proceedings of the 1st World Congress of Paediatric Cardiac Surgery, Bergamo, 19-23 June 1988 (in press)

Quaegebeur 1M, Rohmer 1, Ottenkamp J et al (1986) The arterial switch operation An eight year experience J Thorac Cardiovasc Surg 92: 361-384

Radley-Smith R, Yacoub MH (1984) One stage anatomic correction of simple complete transposition of the great arteries in neonates Br Heart 1 51: 685-686 (abstract) Sidi D, Planche G, Kachaner 1 et al (1987) Anatomic correction of simple transposition of the great arteries in

50 neonates Circulation 75: 429-435 Yacoub MH, Bernhard A, Radley-Smith R, Lange P, Sievers

H, Heintzen P (1982) Supravalvular pulmonary stenosis after anatomic correction of transposition of the great arteries; cause and prevention Circulation 66: 193-197

Arterial Switch for Right Ventricular Failure

R.B.B Mee

Introduction

Atrial operations (Mustard, Senning) for TGA

now yield excellent early results For TGA

with intact ventricular septum (IVS) , elective

atrial repair is now achieved with a minimal

early mortality in many centres

Intermediate-term results show excellent actuarial survival

over the first 10 years Nevertheless,

approxi-mately 10% of patients who have undergone

atrial repair for TGA + IVS display easily

identifiable RV dysfunction with or without

tricuspid valve incompetence (TVI) by 10 years

In some of these patients the dysfunction

appears to be relatively stable or very slowly

progressive In others progressive RV

dysfunc-tion with increasing TVI appears after a period

of apparently good function and leads to a

more rapid downhill course On the other

hand, patients with TGA and ventricular septal

defect (TGA + VSD) appear more prone to

develop RV dysfunction + TVI, and in the

small subgroup of patients with double outlet

right ventricle (DORV) and subpulmonary

VSD, RV dysfunction + TVI appears early

and in a high percentage of patients after atrial

repair In 1980 Trusler et al published

follow-up of 192 patients surviving Mustard repair for TGA + IVS At a mean follow-up of 8 years, 6% had RV dysfunction, 2.6% had RV dysfunction and TVI and 2.6% had TVI alone (11.2% had identifiable problems with the RV) A review of 98 patients surviving a Mustard procedure at the Royal Children's Hospital, Melbourne, for TGA + IVS and TGA + VSD showed 16% (16 patients) with

RV problems The mean follow-up was 7l

years Eleven had RV dysfunction with minimal symptoms, but five patients had definite symp-toms; two patients had died A'review of our

69 survivors of Senning operation followed for a mean period of 2i years showed RV dysfunction in 1 of 32 (3%) patients with TGA

+ IVS, in 3 of 28 (9%) patients with TGA +

VSD and in 3 of 9 (33%) patients with DORV and subpulmonary VSD

In view of the large number of patients with TGA, with or without VSD, who have survived atrial repair, the presence of RV dysfunction

in survivors is a significant clinical problem Treatment is difficult, and the surgical options for this complication are limited In our own experience tricuspid valve replacement alone has little to offer in the long term, particularly

if there is already well-established RV

dysfunc-tion We have replaced four tricuspid valves in

patients after atrial repair for TGA Three died

within 1 year of operation The only survivor

(3 years) is a patient who had well-preserved

RV function at the time of TV replacement A

second surgical option is heart transplantation if

the pulmonary artery pressure is not

signifi-cantly elevated and heart/lung transplantation if

pulmonary hypertension exists The remaining

surgical option is the reversal of atrial repair

and conversion to an arterial switch (Mee

1986) This is only feasible if the left ventricle

is prepared for a systemic pressure workload

A small number of patients may have significant

dynamic (non-organic) left ventricular outflow

tract obstruction (LVOTO) Such left ventricles

are already well prepared, and the patients can

be put forward for a conversion to arterial

switch in one stage The majority of patients

with RV dysfunction and TVI have

near-normal LV pressures at the time when they

present with congestive heart failure These

patients will require a two-stage surgical

approach Firstly, the pulmonary artery is

banded to retrain the LV for a systemic load

Conversion to an arterial switch as the second

stage is delayed until investigations support the

belief that the LV is sufficiently "retrained" to

handle the systemic load At this point it must

be noted that LV retraining requires time As

rapid deterioration in RV performance may

preclude adequate time for LV retraining, the

timing of PA banding is important In our

initial hesitancy in treating these patients we

tended to wait until congestive heart failure

(CHF) was well established; and the trend

towards further deterioration was quite clear

As a result of this policy two of our banded

patients died because there was inadequate

time for adequate LV retraining One of

the survivors of conversion to arterial switch

exhibits significant persistent cardiomegaly and

moderate persistent LV dysfunction Early

banding is therefore advocated We suggest the

pulmonary artery is banded as soon as a

deterioration trend in RV dysfunction is

estab-lished, particularly if TVI is present and if the

original surgery included patch closure of a

VSD

In our view, patients' ventricular function

should be monitored closely after Mustard or

Senning operations The pulmonary artery

should probably be banded before decongestive therapy becomes necessary

Furthermore, the earlier the banding is applied in growing children, the more one can

be confident of progressive LV hypertrophy as the band becomes effectively tighter

In future, "retraining" of the LV may be achieved more rapidly by using an adjustable pulmonary artery band, or possibly by pursuing chemical methods of stimulating the hyper-trop4ic response to banding We are currently investigating the clinical use of orotic acid to stimulate hypertrophy after banding

Problems

Related to Previous Atrial Repair

In the patient who is being considered for conversion from atrial repair to arterial switch repair, there may be additional problems stemming from the original surgery with greater

or lesser bearing on the contemplated sion

conver-Baffle Problems

After Mustard repair, problems relating to the baffle may include sve and/or Ive obstruc-tion, pulmonary venous obstruction, coronary sinus obstruction or baffle leak All these problems can be easily rectified when the baffle

is removed during conversion The above problems are rarely seen after a Senning operation

Arrhythmias

Both Mustard and Senning atrial repair ations are associated with an incidence of postoperative atrial arrhythmias, which almost certainly increases with time Sick sinus syn-drome (tachybradycardia syndrome) is the most common and probably results from sino-atrial node ·damage The medical treatment of atrial arrhythmias may exacerbate RV dysfunction, and the concomitant use of a pacemaker may

oper-exacerbate TVI either by virtue of distortion

of the tricuspid (transvenous) valve, or by virtue

of altered sequence of ventricular contraction

(transvenous or epicardial ventricular pacing)

Related to the Concept of Atrial Repair

Septal Bulging

Septal bulging causes L VOTO If such

obstruc-tion is significant then conversion to a switch

repair may be simplified, in that conversion

can be performed in one stage without the

need for preliminary pulmonary artery banding

On the other hand, subpulmonary obstruction

creates a jet which may damage the pulmonary

valve, causing incompetence which may

preju-dice future conversion to a switch

L V Dysfunction

LV dysfunction is occasionally observed after

atrial repair The cause is not clear but may

be secondary to long-standing RV dysfunction

A remote possibility is long-standing coronary

sinus ostial obstruction from the baffle LV

dysfunction, if significant, makes consideration

of conversion to an arterial switch somewhat

irrational Furthermore, the response to

attempted pulmonary artery banding is unlikely

to be rewarding

RV Dysfunction and Tricuspid Valve

Regurgitation

Mild forms of R V dysfunction are now

recog-nised to be common after atrial repair for

simple transposition (F<;>uron et al 1980;

Badno-Rodrigo et al 1980; Minomiya et al

1981) Such minor levels of dysfunction are

now quite readily documented by radionuclide

scanning, particularly under exercise

con-ditions, when it is frequently observed (50%)

that there is no exercise-related increase in

ejection function Evidence so far suggests that

minor degrees of RV dysfunction are likely to

remain unchanged for many years In some

cases diminished contractility of the right

ventricle is observed before atrial repair is performed As RV dysfunction progresses, the

RV volume (end-diastolic and end-systolic) increases, and the ventricular septum bulges more to the left Increased tension on the chordal apparatus of the tricuspid valve may

be instrumental in initiating tricuspid ence in some cases With TVI, volume loading

incompet-is added to the dincompet-istended RV, further increasing

RV dimensions Tricuspid valve ring dilatation

is also a consequence of increasing RV sions and volume loading

dimen-In other cases it is certain that the tricuspid valve is either previously malformed, or is damaged by the presence of the VSD, or is damaged as a result of VSD closure (either' at the time of surgery or subsequently by cusp adherence to the patch) When significant TVI

is based on organic damage and RV function

is well preserved, then tricuspid valve repair or replacement may offer a reasonable outcome The underlying cause of late RV dysfunction remains uncertain (Sideris et al 1982) The

RV is certainly less well designed for pressure work than the LV, and therefore is probably less robust and less able to tolerate additional imposed load It may be argued that

high-in the natural order of thhigh-ings, there is a range

of right ventricles in transposition At one end

of this range, the RV has much reserve and in these cases, we could expect the RV to function

as a systemic ventricle after atrial repair for a full lifetime At the other end of the range are right ventricles with minimal reserve and these are the ones that exhibit dysfunction earliest The middle range of right ventricles, on the basis of this thesis, will last reasonably well but probably not for a full lifetime If this is the case, then one can expect increasing numbers of patients with RV problems as a function of elapsed time after surgery

There is reasonable evidence to suggest that the early phase of this phenomenon has already been observed This concept is further sup-ported by the higher incidence of systemic (RV) ventricular failure when transposition is associated with a VSD, and the tendency for

a more rapid downhill course for patients with TGA + VSD who have developed RV problems after atrial repair When a VSD is present there are additional potential hazards for the right ventricle These include the effects

of preoperative volume loading and CHF,

longer aortic cross-clamp times during repair,

the previously mentioned organic tricuspid

valve damage, and the fact that a portion of

the ventricular wall will be non-functional after

VSD patching The larger the VSD, the larger

the proportion of ventricular septal wall that

will be permanently non-contractile

Management and Surgical

Technique

Stage I Pulmonary Artery Banding for

RV Failure after Mustard/Senning

Indication and Timing

In order to arrive at the decision to convert an

atrial repair to an arterial switch, it is necessary

to document that RV dysfunction and TVI are

not stable, and that there has been

deterio-ration It is difficult to be dogmatic over the

optimal timing of Stage I (application of a

pulmonary artery band) Clearly, it is useful

to have some insight in a given patient into

the rate of deterioration of RV function, in

order to leave sufficient time for LV

"retrain-ing" before conversion to arterial switch

Cur-rently, our policy is to schedule the patient for

pulmonary artery banding at the time when

decongestive therapy is first considered to be

necessary for management of heart failure In

two of our cases, time was obviously too short

One patient died from arrhythmias within 6

months of banding and in another, because of

repeated hospitalisation for uncontrolled CHF

and progressive ventricular arrhythmias, we

performed conversion within 6 months of

banding The patient died a few hours after

operation from progressive LV failure The LV

was still thin-walled at post-mortem (5 mm)

Therefore it could well be argued that the

documentation of deterioration in RV function

or increasing TVI should be the trigger for

initiating Stage I even before symptoms or

signs of CHF are evident

Certainly such a policy would be less likely

to result in a forced premature progression to

Stage II, because of deteriorating cardiac status

It appears that in those patients with TGA + IVS there may be a progressively slower RV dysfunction and TVI than in those who have had VSDs patched In those patients who are clearly deteriorating rapidly, cardiac transplan-tation may be the only option

nasotra-Surgery

A midline sternotomy is performed with an oscillating saw Adhesions are taken down with coagulation diathermy until the aorta, main pulmonary artery (MPA) and bifurcation are well exposed The banding site is selected carefully to avoid distortion of the pulmonary valve on the one hand, or the pulmonary artery bifurcation on the other A 5-0 Prolene purse-string with a fine polythene "snugger" is inserted proximal to the proposed banding site,

an angiocath is connected to the pressure line,

a transducer is positioned and both phasic and mean proximal P A pressures recorded

The MP A is then encircled with banding material (Dacron tape impregnated with sili-cone glue), 4 mm or 7 mm wide, depending

on the patient's size The band is tightened acutely for 2-3 s and the maximal proximal

MP A pressure generated is recorded The band

is loosened and the return of haemodynamic stability awaited The band is then gradually tightened to the point where any further tightening results in a rise in systemic venous pressure or a fall in systemic arterial pressure Generally, this achieves a proximal MP A pressure of about 70% of the previously observed maximal proximal MPA pressure (see Table 16.1)

The band is then accurately fixed to the

MP A wall with two or three interrupted 5-0

Table 16.1 Stage I: LV performance at pulmonary artery banding

Case Age at inflow Age at PAB Pre PAB LVp Maximal LVp Post PAB LVp

LVp , left ventricular pressure; PAB , pulmonary artery banding

Prolene sutures (Fig 16.1) A dopamine

infusion of 5 f.Lg/kg/min is started

Haemody-namic stability is then observed over the

next 20-30 min before attempting to close the

sternum Sternal closure is achieved after

covering the front of the heart with a layer

of ultrathin Gore-Tex membrane to prevent

cardiac adherence to the sternum, and to

provide safer re-access at the time of conversion

to arterial switch

Postoperative Care

The patient is maintained paralysed and

venti-lated for a minimum of 24 h Weaning from

the respirator is a gradual stepwise process,

while watching for signs of LV failure (rising

systemic venous atrial pressure, hepatomegaly

and general signs of decreasing cardiac output)

Failure to respond to an increase of dopamine

to 10 f.Lg/kg/min within a short period should

Fig 16.1

lead to urgent echocardiographic evaluation of

LV dimensions and function If these confirm acute LV failure despite increased dopamine, then urgent measures should be taken to loosen the band In our small series this has not occurred The dopamine infusion is continued for at least 5 days postoperatively Digoxin and diuretics are recommenced the morning after the operation Ultrasound and Doppler are used to confirm the position of the band relative

to the pulmonary valve and pulmonary artery bifurcation, to measure the gradient across the band, and check for pulmonary valve regurgitation At 1 week , radionuclide studies are performed to check RV and LV function Any evidence of deteriorating LV function should be viewed with concern, dopamine recommenced and, in the absence of improve-ment, consideration given to loosening the band Again, we have not yet been required

to loosen a band

Results

Since 1981, 10 patients have been submitted for pulmonary artery banding after Mustard and Senning operations because of RV prob-lems All survived surgery One 17-year-old underwent two attempts (left thoracotomy and midline sternotomy with cardiopulmonary bypass support) Both were unsuccessful because we were unable to place the band without compromising the MPA bifurcation or the pulmonary valve The MPA appeared to

be extremely short This patient died 9 months later from her progressive RV dysfunction and TVI Nine patients have been successfully

banded One died suddenly within 6 months

of banding (Case 8) and within 9 months of

first presenting with severe RV dysfunction,

TVI and CHF Of the remaining eight patients,

five have undergone conversion to arterial

switch, with one death The other three patients

are waiting for adequate LV hypertrophy

5 converted to switch (Cases 1 2, 3, 4, 9)

3 waiting (Cases 5, 6 7) PAB, pulmonary artery band; CHF congestive heart failure

Follow-up

Ultrasound and Doppler studies and

radio-nuclide assessment of RV and LV function are

repeated at about 2-monthly intervals LV wall

thickness (systolic and diastolic) are measured

and Vector cardiogram and ECG followed to

Table 16.3 Stage II: conversion to switch

VSD (Senning) TGA +

VSD (Mustard) TGA +

VSDs (Senning) DORV (Senning)

TGA +

VSDs

Age at PAB 2.5 years

a new and important dimension to the ment of these patients after banding We have found this a most useful tool fOl: measuring the gradient across the pulmonary artery band during the retraining period In our experience

manage-we are certain that the gradient falls after banding, particularly in patients with a large

MP A We believe that the result of initial banding is an infolding of the MPA wall, the pattern of which is not controllable These

MP A folds occupy potential lumen space inside the band As time goes by these folds become smoothed out from within and the MP A lumen within the band becomes larger with consequent fall of gradient We now believe that a fall in gradient within the first 2 weeks of MP A banding should lead to reoperation before adhesions became difficult to manage, and to further tightening of the band Otherwise valuable "retraining" time may be lost We believe that critical banding in a fully septated heart requires more precision than in a heart which has a VSD and/or an ASD For obvious reasons there will be less tolerance of marginal overbanding in the fully septated heart A theoretically better approach would be to use

Age at conversion 3.5 years 14.5 years

6 years 8.5 years

6 years

LVp (mmHg)

Falling left ventricular ej<;ction fraction Emergency Satisfactory

Good

Follow-up time; result

31 months; very well

30 months; satisfactory

Early death (LV failure) Late death 1 year

Supraventricular tachycardia

LV failure

7 months; very well DORV, double outlet right ventricle; LVp, left ventricular pressure; PAB, pulmonary artery banding; TGA, transposition

of the great arteries; VSD, ventricular septal defect

a precise externally' adjustable band We would

add a caution: such a device needs to embody

in its ,design the ability to make tiny

adjust-ments, each of which are exactly reversible

In the absence of such a device, more

consideration should be given to reoperation

to tighten the band, in order to speed up the

"retraining" process In the rapidly growing

neonate and infant, with unrepaired TGA, it

is now known that LV hypertrophy after MP A

banding can be very rapid indeed, possibly

achieving adequate dimensions to support the

systemic circulation within 1 month So far,

such rapid hypertrophy has not been seen in

the older child or teenager In larger patients

and patients with significant CHF one cannot

rely on growth of the patient to tighten the

band naturally We are currently exploring

the use of orally administered orotic acid

as a possible method of stimulating the

hyper-trophic response, but as yet have nothing to

report

The length of time required for LV retraining

will vary from patient to patient In our limited

experience to date, without further reoperation

and band tightening it seems unlikely that a

period of less than 1 year will be adequate As

yet, we have no recommendations on choosing

an end-point for safe conversion to arterial

switch The presence of systemic pressure in a

well-functioning LV at catheter study is

cer-tainly a criterion we would accept for

proceed-ing to ·conversion It is probable that an LV

pressure of 75% of systemic pressure will be

adequate (see Case 2) and may have to be

accepted in the presence of progressive RV

dysfunction and CHF We are much less certain

of an LV pressure which is only 60% of

systemic pressure measured at rest, although

we have two early survivors under these

conditions (Cases 2 and 4, Table 16.3)

A great deal more experience is required

before a precise protocol for the

decision-making process at this stage of management

can be elaborated We believe that the change

in LV pressure produced by changing cardiac

output (isoprenaline infusion) during

pre-con-version catheter study or Doppler assessment

should probably also be taken into account In

our oldest patient (Case 2) who had been

banded for 3 years, restudy LV/RV pressure

ratio was 60%-65% at rest, but during

isoprena-line infusion the ratio changed to 120% This patient survived conv'ersion to arterial switch

Stage II Conversion of Mustard!

Senning to Arterial Switch

Anaesthesia

The patient is induced with morphine and/

or Fentanyl and nasotracheal intubation is achieved under non-depolarising muscle relax-ation Radial artery and internal jugular press-ure lines are inserted and monitoring for ECG, and nasopharyngeal, oesophageal and toe tem-peratures are established A urinary catheter

is inserted

Surgery

A midline sternotomy is performed with an oscillating saw and the previously placed Gore-Tex membrane removed Adhesions are taken down over the front of the heart, the right atrium, SVC, IVC and great arteries The aorta

is separated from the MP A, the band site is defined, and the RPA and LP A are dissected out into the hilus of each lung Heparin (3 mg/kg) is given intravenously, the aorta

is cannulated high, and the two cavae are cannulated directly using Pacifico metal cannu-lae (Fig 16.2) Phenoxybenzamine (1 mg/kg)

is given slowly intravenously, starting just before commencement of cardiopulmonary bypass We prefer a long-acting dilator to provide steady-state alpha blockade The pati-ent is slowly core cooled to 20°C nasopharyn-geal, during which time the ductus ligamentum

is divided, the pulmonary artery band removed and full mobilisation of the MP A, RP A and LPA is completed Adhesions over the left heart are taken down with the heart empty and beating The aorta is cross-clamped and tardioplegic solution is infused into the aortic root Caval snares are tightened and the pulmonary venous atrium is' opened through the original suture line in order to decompress the left heart (Fig 16.2) Cardioplegia is repeated every 20 min while the aorta is cross-clamped Our cardioplegia solution in patients over 10 kg weight contains no albumin and is

Fig 16.2

made up by mixing two custom-made ampoules,

one of base and one of buffer:

The cardioplegia solution is pumped into the

aortic root at a rate of 112 mllmin/m 2 body

surface area (BSA) for 4 min for initial

cardi-oplegia and for 2 min at each subsequent dose

For various degrees of cardiomegaly flow rate

is variously increased up to 150 mllmin/m 2

BSA At the above flow rates aortic root

pressure is usually no more than 60%-70% of

normal mean arterial pressure for age The

solutron is recirculated continuously through a

closed circuit including the cooling coil in the

Fig 16.3

ice slush and the reservoir, between doses of cardioplegia In this way, the cardioplegia solution is maintained at 3-4 °C and is delivered

to the aortic root at about 5 0c

Silastic vessel loop snares are tightened on right and left pulmonary arteries Figure 16.2 shows the general organisation of the operative field at this stage The initial "left" heart decompression incision in the pulmonary venous atrium is shown in Fig 16.3 for a previous Senning, in Fig 16.4 for a previous Mustard with an oblique incision and in Fig 16.5a-c for a previous Mustard in which other types of atrial incisions have been used: (a)

transverse incision, (b) transverse incision with augmentation patch and (c) transverse incision with V-Y advancement The light dotted line

in Fig 16.5 indicates the original suture line; the heavy dotted line indicates the incision

Fig 16.4

b

c

Fig 16.5

recommended for re-entry Note that in each

type of transverse incision the reopening of the

pulmonary venous atrium needs only to extend

posteriorly as far as the line of the interatrial

groove

The ascending aorta is transected

immedi-ately above the aortic valve (Fig 16.6), and

the commissures and coronary artery ostia are

carefully probed to identify the branching

patterns The MPA is opened transversely at

the band site and the pulmonary valve

inspected The thickened, scarred pulmonary

artery wall is excised above and below the

band site The coronary arteries are excised,

each with a generous cuff of aortic sinus wall

(insert to Fig 16.6) Medially based "trapdoor"

flaps are created in the facing sinuses of the

proximal pulmonary artery and the coronary

arteries are sewn in with 6-0 or 7-0 Prolene

(Fig 16.7) The insert to Fig 16.7 shows the

effect of the medially based trapdoor flap in

reducing the angle of attachment of the

coron-ary artery to the aortic sinus, compared with

the situation when a defect is created in the

previous pulmonary artery without a trapdoor

The distal ascending aorta is placed under

the pulmonary artery bifurcation (Lecompte's

a

b

Fig 16.6

Fig 16.7

Fig 16.8

manoeuvre) and the proximal pulmonary artery

bearing the translocated coronary arteries is

anastomosed end-to-end to the distal ascending

aorta with running 5-0 or 6-0 Prolene (Fig

16.8) Cardioplegia is then repeated and the

Senning or Mustard repair taken down and the

atria reseptated

Mustard Take-down and Atrial Reseptation

Take-down of a Mustard repair and atrial

re'septation is relatively simple The original

incision in the right atrium is opened sufficiently

to give adequate access to the baffle (Fig 16.9)

Removal of the whole baffle is recommended as

well as removal of any scar tissue, particularly

around the caval orifices Figure 16.10 shows

the initial incision detaching the baffle from

the remnant of the septum near the tricuspid

valve Figure 16.11 shows the baffle completely

super-of the atria (insert to Fig 16.11) If the coronary sinus was originally left on the

Coronary sinus

Fig 16.11

Coronary sinus

Fig 16.12

pulmonary venous side then baffle excision is

safer and simpler

Reseptation is straightforward using a

0.55 mm thick Gore-Tex patch tailored to the

correct shape without redundancy and sewn in

with running 5-0 Prolene The coronary sinus

ostium now opens into the restored right

atrium Figure 16.12 shows reseptation almost

completed, allowing for left atrial de-airing by

sustained pulmonary inflation just prior to tying

the suture The insert to Fig 16.12 illustrates

the patch almost completed in a patient with

previous coronary sinus cutback

Fig 16.13

With reseptation of the atria restored after either Mustard or Senning, it is important to allow bronchial collateral blood to be vented This is done via the pulmonary arteries by releasing the RPA and LPA Silastic snares

Senning Take-down and Atrial Reseptation

The pulmonary venous atrial suture line is taken down completely (see dotted line Fig 16.13) Some surgeons when performing the Senning operation carry the superior end of the pulmonary venous atrial suture line directly across the region of the SA node In taking down such a suture line, it would be wise to leave a small remnant of atrial wall still attached

to the region of the SA node in order to protect this structure Figure 16.14 shows the pulmonary venous atrium opened completely, exposing the suture line of the systemic venous atrium and showing the remnant of atrial wall left in the region of the SA node The take-down of the systemic venous atrium is commenced anteriorly at the midpoint and extended inferiorly and superiorly

At the superior end of the anterior systemic venous atrial suture line care must be taken to preserve the tissue of the SA node The usual appearance of this region is now altered because the original epicardial surface has become endothelialised and the atriosuperior venocaval junction is no longer identifiable Figure 16.15 shows the anterior suture line taken down completely, the baffle pulled towards the

Fig 16.14

Fig 16.15

surgeon, and commencement of the take-down

of the posterior suture line, again starting

at the midpoint and working inferiorly and

superiorly Figure 16.16 shows both suture lines

of the systemic venous atrium completely taken

down The Senning baffle is now flail attached

only at the superior and inferior ends The

most posterior part of the baffle, which has

been detached from around the left pulmonary

veins (labelled xx), has been flapped to the

right to show the remains of the original atrial

septum The original interatrial groove is

labelled gg in Fig 16.16

The atria are now ready for septation and

there are two options:

Option 1 If the posterior wall of the systemic

venous atrium (remains of interatrial septum)

is small (area between the lines marked gg and

xx in Fig 16.16) then this portion of the

Senning baffle is left flapped to the right and

edge xx is sewn around the right pulmonary

veins (arrow in Fig 16.16) with running 5-0

Prolene (insert to Fig 16.17) Then the anterior

edge of the Senning baffle is retracted towards

the surgeon and the line marked gg (Fig 16.17)

is exposed This line represents the junction

between the original atrial septum and the right

atrial wall and corresponds to the internal

equivalent of the right interatrial groove

marked gg externally on Fig 16.16 Atrial

septation is performed with a Gore-Tex patch

(0.55 mm thickness) shaped to fit the defect

marked a superiorly, anteriorly and inferiorly

(the line of the original interatrial septum) and

Fig 16.16

marked gg posteriorly (Fig 16.17), sewn in with running 4-0 Prolene (Fig 16.18) The left atrium is de-aired by hyperinflating the lungs before final closure, and immediately after closure the bronchial return is vented via the pulmonary arteries by releasing the Silastic snares on the LPA and RPA

Option 2 If the posterior wall of the systemic venous atrium (remains of original interatrial septum) is larger, then this can be used to septate the atria In this case , as shown in Fig

Fig 16.17