Ebook Board stiff tee - Transesophageal echocardiography (2nd edition): Part 2

(BQ) Part 2 book Board stiff tee - Transesophageal echocardiography presents the following contents: Left ventricular systolic function, the 17 segment model, congenital heart disease, artifacts and pitfalls, related diagnostic modalities, sonographic formulas, test questions,...

For some reason there is a lot of focus on the left ventricle and its

evalu-ation on TEE, both in the operating room and on the boards This most

likely has to do with the fact that it’s pumping blood to the entire body,

thus keeping you alive The easiest way to start your evaluation of the left

ventricle is to know what a normal left ventricle looks like

The shape of the LV should look somewhat like a football If you drop a

TEE probe in someone and the heart is closer to a basketball than a

foot-ball, something is wrong

So, now you know how to eyeball the heart and tell grossly if it’s normal

or not, but what about an actual measurement? LV function is typically

measured numerically by the ejection fraction (EF) That is, how much

blood that goes into the LV goes out through the aorta?

CHAPTER

Eric W Nelson

Good

EF can be calculated by measuring the fractional area of change (FAC)

of the left ventricle A true long- or short-axis cross section is required

being careful not to foreshorten Foreshortening is a term commonly

used by echocardiographers to describe the heart when it is compressed

because of the viewpoint taken With modern TEE machines all you have

Bad

to do is outline the end-diastolic area and the end-systolic area and the machine will crunch the numbers.

FAC = (end-diastolic area – end-systolic area)/end-diastolic areaYou can also estimate EF via the eyeball method, which is what most people do On the test you should be able to look at an image and deter-mine the difference between an EF of 25% and 55% Which is pretty easy!

One thing to keep in mind whether using the eyeball method or doing an actual measurement is don’t jump to conclusions based on one view A single slice may look great, but remember it’s only part of the heart and another part may not look so good Also, if you are foreshortening or not getting a “true” cut of the LV your read is going to be off Make sure you eyeball the LV with multiple omniplane angles and also in both the trans-gastric and midesophageal views

ABNORMAL LV SYSTOLIC FUNCTION

Naturally, the first thing that comes to mind is ischemia…if this wasn’t your first thought you may want to retake your boards There are also a lot of other things that may cause abnormal LV function

n Ischemia, just can’t say it enough

n Ventricle—infiltrative diseases that cause restrictive physiology such as amyloidosis cause global impairment

n Pericardial space—tamponade either from an effusion or blood TEE is great at not only making this diagnosis, but also locating where the effusion is around the heart and whether it is loculated

n Pleural space—tension pneumothorax causes decreased venous return thus decreasing preload and ventricular function

n Metabolic—hypoxemia, hypoglycemia, anemia, hyperkalemia, and

a vast array of other metabolic abnormalities

CARDIOMYOPATHIES Hypertrophic

There are four different types of hypertrophic cardiomyopathies, although the most famous is septal hypertrophy leading to subaortic stenosis or

“hypertrophic obstructive cardiomyopathy”, which all the cool kids just call HOCM (pronounced hokum)

HOCM is an inherited cardiomyopathy It is autosomal dominant with limited penetrance, unless of course you are the patient then it is a very penetrating diagnosis!

Chapter 13 Left Ventricular Systolic Function 125

HOCM AS

With hypertrophic cardiomyopathies systolic function typically is not the

problem, rather the heart has a hard time relaxing, like that one attending

we’ve all had with the vein in his forehead that seems to keep growing

and may pop at any minute!

An important point about HOCM is the picture you see on TEE Some

people call this the “dagger sign” When a continuous wave Doppler

is placed across the left ventricular outflow tract, or LVOT, and the AV

the outflow pattern will resemble a dagger rather than the nice rounded

appearance of someone without this problem This is secondary to the

ventricle being so empty at the end of systole and the septum being so

huge an obstruction actually occurs

Keep in mind that patients with HOCM are also more prone to SAM

or systolic anterior motion of the mitral valve Since the outflow tract

is already narrow, it’s easy for the anterior leaflet to get sucked in and

impede flow

The definitive answer to relieving HOCM is surgical resection of the septum

TEE plays an important role here in order to determine preop if the surgery

is necessary and postop if there was enough septum resected, not enough,

or too much If not enough was taken the obstruction will remain, but if the

surgeon got a little greedy the patient may end up with a VSD Also

remem-ber that there are conduction firemem-bers running through the septum It’s not

uncommon to have a heart block after this type of surgery

Too Little Too Much Just Right

Medical management of HOCM involves keeping the heart full; ber that the obstruction occurs when the heart is empty; and also decreasing contractility.

Restrictive Hypertrophic

Alright, we’ve determined that we have a restrictive cardiomyopathy, but where’d it come from? Well, the list is long and distinguished There are a lot of things that can “sneak” into the myocardium and cause restriction:

n amyloid

n sarcoid

n glycogen from patients with glycogen storage disease

n eosinophils from eosinophilic myocarditis (also known

as Loffler’s)Like hypertrophic cardiomyopathies, restrictive cardiomyopathies mainly present a problem in diastole that is the heart does not relax well enough to accept blood Remember to go over the various dia-stolic E/A patterns and pulmonary venous flow because these do show

Chapter 13 Left Ventricular Systolic Function 127

Clot

Dilated

Remember at the beginning of this chapter when I mentioned that the

heart shouldn’t look like a basketball? Well that’s exactly what this type

of heart looks like It’s big, the walls are thin, and it really isn’t doing

much at all Keep your eye out for thrombi, as there isn’t much going on

so clot formation is possible

Like everything else there is a list of what causes dilated cardiomyopathy

n Ischemic

n Post viral

n Peripartum

n Alcohol

n Idiopathic (a doctor’s way of saying “I just don’t know”)

n And numerous others

3 Where is the most likely place to find thrombus in the LV?

5 What causes hemodynamic compromise in patients with HOCM?

A Anatomic outflow tract obstruction

B Physiologic outflow tract obstruction

F All of the above

9 True or false: It is possible to evaluate the ejection fraction of the heart by one view on TEE

Chapter 13 Left Ventricular Systolic Function 129

MYOCARDIAL SEGMENT IDENTIFICATION

Hear ye, hear ye The Office of Homeland Security is not going to shoot

me for revealing any state secrets here You will need to know these

seg-ments and you will need to know which coronaries feed which walls and

which segments

I kid thee not

I speak not with forked tongue

This is a for sure on the test

The first time you see it you’ll quasi freak, because it looks so complex,

but when you think of all the other stuff you memorized to get this far, it’s

not so bad Plus there’s a logic to it, so don’t go off the deep end

First, the whole thing, then we’ll back up and break it down

SEGMENTS—DON’T FREAK

A

Basal 6 Mid 6 Apical 4

DONUT AT EACH SLICE

B

A

S Not in apical

Not in apical I

WHICH WALL IS WHICH?

14 Segmental Left Ventricular Systolic Function

John C Sciarra and Christopher J Gallagher

I found it easiest to start with the cross sections That way you can at least always know what’s “directly across” from you Then you can take the long views and start to put it together.

So, think of three of these lying on top of each other, starting at the top

of the ventricle, right next to the mitral valve Three layers of six:

The basal 6 segments are next to the mitral valve

The middle 6 segments are next down, at the level of the papillary muscles

The lower, or apical, 6 segments come next

BUT WAIT!

Though it would make sense to do 6/6/6, the SCA (perhaps fretting about the demonic number 666 from The Omen), only recognizes four segments in the ever-narrowing apex

Lose the posterior and the anteroseptal segments there In the apical, you just have inferior, anterior (across from each other, remember), and septal and lateral (across from each other too)

Now, put it back together, piece by piece, until it makes sense If you are still confused, stay tuned for the 17 segment chapter

CORONARY ARTERY DISTRIBUTION AND FLOW

REAL WORLD NOTE Major, major importance that you know this This ties in with the extremely practical dilemma that you face on a daily basis: “Is the new graft working?” If a wall fed by, say, the right coronary graft was working, and now

is not working, hey, look at the graft for kinks, disconnects, clots, dissections It’s

a hell of a lot easier to recognize the problem and fix it now than to find out later and lose a chunk of myocardium

TEST NOTE Vintage testable material here, folks A little brutal memorization (come on, there are only three vessels, it’s not that bad) and you should nail these questions

Chapter 14 Segmental Left Ventricular Systolic Function 133

Pictures tell it all:

CORONARY DISTRIBUTION

A

RV and Inferior Wall Posterior and Lateral Septal, AS, Anterior

Right Circumflex LAD CORONARY DISTRIBUTION

B

4-Chamber

LAD

Know these cold!

LAD LAD Circumflex

Circumflex

Right Right

2-Chamber

LAX

Let’s put it into words, just in case you’re less of a visual learner

The right coronary feeds the inferior wall and right ventricle

The left anterior descending feeds the anterior and septal walls (No

won-der an LAD infarct is so problematic.)

The circumflex feeds the posterior and lateral wall

Everyone studies the hell out of this issue, drawing the pictures over and

over again, flashcards, you name it Get this stuff down but down

Here is a little memory helper I made up, I call it the “coronary artery

memory helper”:

LM → LAD → Diags (the “D” in lad leads into the “D” in diagonals)

Circ → OMs (circumferential looks like the circumference of the “O” in

Obtuse Marginal)

RC → PDA (the right hand [RCA] writes on the palm pilot pda)

NORMAL AND ABNORMAL SEGMENTAL

DYSFUNCTION

Assessment and Methods

Keep your eyes open, that’s the method The wall motion

abnormali-ties you see will not be subtle Every test-taker since the dawn of time

emphasized that to me

“You’ll see it moving, then BOOM, it ain’t moving.”

And in real life, that’s what you see too As soon as a wall gets ischemic, the motion disappears Keep in mind, the normal movement of a wall is thickening and an inward movement

At the meeting, they get a little more scientific than this, saying “Normal contractility results in 30% thickening of the wall, hypokinetic is 15%, akinetic is, well, 0%, and dyskinetic means it bulges outward”

Others gets a little more Gestalty:

In the OR, I’ll put my finger in the center of the ventricle on the monitor and see if different wall segments move in toward my finger

One trick I stumbled upon is the value of fast forward Tape a bit, then rewind and look at the walls in fast motion Believe it or not, when the ventricle’s going super fast, the dyskinetic or akinetic wall stands out better than at regular speed

In your studying, look at either the tapes or the CDs This is a total ing picture experience”, for there is no other way than to drill these

“mov-On the tapes from the 2002 meeting, they recorded the “Regional Wall Motion Unknown” session That is the best way I found to practice pick-ing out the “mystery wall motion abnormality.” (Quit laughing as I men-tion “tapes”, go online and look up a few examples of regional wall motion abnormalities on the Internet.)

DIFFERENTIAL DIAGNOSIS

Well, gee whiz, what else could it be?

Wise counsel says, “Believe bad news and act accordingly” Other than

a graft not working or a native vessel being occluded, there aren’t too many other things it could be The main aspect of the differential should center on which catastrophe afflicted your graft:

n Air embolus (particularly after an open procedure)

Chapter 14 Segmental Left Ventricular Systolic Function 135

n Spasm of the internal mammary (a surgeon at the meeting and in

the tapes points out that spasm of the internal mammary graft is an

oft-cited excuse In reality, the graft was poorly placed, kinked, or

clotted off, and the all-encompassing excuse of “Oh, it must have

been spasm” is pulled out for public consumption.)

n Too long of a graft, leading to a kink

n Too short of a graft, leading to a squinking shut of the graft as it’s

stretched flat as a pancake

n Clot from, perhaps, hypotension and stasis (Eeek! That can be a

result of “Anesthetica Imperfecta”!)

n Dissection

Whatever it may have been, when you see a new wall motion abnormality

that you thought you should have fixed, take a look-see

CONFOUNDING FACTORS

Tethering can throw you off the hunt when examining regional wall

motion abnormalities

TETHERING Can’t move as well.

Can’t move as well.

Infarcted./Dead and gone.

A hypo-, dys-, or akinetic area can “hold back” a normal area (You may

be able to run around pretty energetically, but if I jump on your shoulders

and say, “Yeehaa! Giddyap!”, your motion may slow down considerably

You have been tethered by my bulk.)

The angle of your examination may throw you off too If you get a really

foreshortened view of the ventricle, for example, you may not get a clean

look at one segment; rather, you’ll see a lot of segments at once and

won’t be able to make a clean diagnosis

LEFT VENTRICULAR ANEURYSM

An aneurysm is a thinning of the entire wall of a structure So, on echo,

a ventricular aneurysm is seen as a dyskinetic region (bulges outward in

systole) that has a diastolic contour abnormality (keeps bulging outward

even after systole is over) In other words, the damned thing is always

bulging out Kind of the “love handles” of the heart

Of specific diagnostic interest, an aneurysm has a smooth transition from

normal myocardium to thinned aneurysm There is no sharp angle or neck

(as we’ll see with pseudoaneurysms or ventricular ruptures in just a minute)

The love handle analogy helps again Love handles (however much they may plague us, uh, more mature gentlemen) at least have an aestheti-cally pleasing smoothness as they transition from the torso to the love handle proper.

Aneurysms are most often found in the apex, though they can occur elsewhere And aneurysms, with their underlying stasis, can give rise to thrombi

LEFT VENTRICULAR RUPTURE

For a big-time ventricular rupture, skip the TEE Grab a pathology text and head for the refrigerated surgical suite in your hospital’s basement

A survivable rupture through the myocardium but contained within a

“skin” of pericardium is called a “pseudoaneurysm” On echo, you don’t see the smooth transition of the true aneurysm; rather, you see a nar-rowed neck at the site of the breakthrough

PSEUDOANEURYSM

Ruptured ventricle “held”

by pericardium Abrupt

Narrow neck

If you want to get all quantitative and anal about it, the ratio of the neck to the maximum diameter of the pseudoaneurysm should be less than 0.5 But give me a break; if you know what happened, the difference between

an aneurysm and a pseudoaneurysm should jump out at you

QUESTIONS

1 Regarding myocardial stunning:

A Ischemia tends to produce more severe wall motion abnormalities

B Stunned myocardium shows a gradual improvement and function

in the first minutes to hours following separation from bypass

C Stunned myocardium may be recruited to contract with inotropic stimulation

D Inotropic stimulation may worsen function in an ischemic segment

E All of the above

2 Concentric LV hypertophy is:

A A really big heart

B Commonly called “cow heart”

C Wall thickness increased in proportion to the increase in chamber size

D Wall thickness increased out of proportion to chamber size

E Wall thickness inversely porportional to chamber size

Chapter 14 Segmental Left Ventricular Systolic Function 137

3 Eccentric LV hypertophy is:

A A really big heart

B Commonly called “cow heart”

C Wall thickness increased in proportion to the increase in

chamber size

D Wall thickness increased out of proportion to chamber size

E Wall thickness inversely porportional to chamber size

ANSWERS

1 E

2 D

3 C

(Update note: In the ancient history of the first edition, there were 16

seg-ments Apparently we have evolved a 17th segment!)

This chapter requires some artist skill When I say some, I mean very

lit-tle If you can draw a line and a circle you are, for the purposes of this

chapter, an artist

The 17 segment model is the way we as doctors communicate which

sections of the heart we are talking about It is also a great tool for

designing test questions For example, the patient is a gunshot wound

victim, and he has a hole in segment 8 What coronary artery is spurting

blood? What leads on the ECG do you expect to see abnormalities? See

what I mean? Well, I am not going to tell you the answer; you just have to

read on—and draw And draw you will You will draw what I call:

“The 17 Segment Star”

First off, draw a line Just a straight line As seen below this is a straight line

A line

Wow, that was not so bad Now comes the tricky part You have to add

two more lines in a cross pattern as seen below It kind of reminds me of

an asterisk, or star That’s you–an echo star!

Grip your pencil tightly because I am going to ask you to do something

completely different Draw a circle on top of your star

CHAPTER

John C Sciarra

Good job Picasso, you have drawn the basic foundation for the 17 ment model Next we have to number the segments Start in the lower left, inside the circle, and do 1 thru 6, as seen below.

start here

Now start again outside the circle at the same lower left and do 7 thru 12 It should look like this If you are not drawing at this point and just reading you are missing the point Get out your pen and do it

11

10

9

8 2

5 4

3

6

1 12

7

Chapter 15 The 17 Segment Model 141

13 thru 17 start close to your original starting point, which is the

bot-tom Circle around and finish at the bottom with 17 17 is the apex or

bottom of the heart, so that is where the number should be It should

look like this:

15 11

10 14 9

8 13 17 2

7 16

That’s it Now you have to practice this without looking Go ahead Find

a piece of paper and start with the line, and finish with 17 You should be

able to do this in 5 seconds I am waiting… Do it

Now that you are an artist, you may feel like painting your living room

Hold on, since we now need to go over how your master work relates

to the heart Your 17 segment model is a segmental version of the cross

section of the heart as seen below, which you may recognize from other

sections in this book Or a dozen other inferior books on TEE

Schematic of LV in Cross Section

AS S

P L I

We start at the top of the heart and work our way to the bottom, ing as we go “Wait” you say The number one is in the wrong place This

number-is due to the fact that in TEE things are backwards from trans-thoracic scanning I just put these images here to show you how the numbers relate to the levels: basal, mid, apical, and apex

Apical Mid Basal

13

15

16 14

7

10

12 8

LAD RCA LCX

11 9

1

4

6 2

5 3

This is the image you might see in most cardiology textbooks—if you ever dared to crack one open

1 7

6 2

8

14 17 16

12 13

15 11 510

4

9 3

of the page is the back of the heart—the inferior portion—and the front

of the heart is at the bottom of the page or TEE image—anterior This should all be crystal clear in the cool exploded 3-D image I made below, which I drew from an actual exploded heart

Chapter 15 The 17 Segment Model 143

7–12

13–16

17 RV

To review the coronary anatomy Which really shouldn’t be

neces-sary—but what the heck:

LM → LAD → Diags (the “D” in LAD leads into the “D” in diagonals)

Circ → OMs (circumferential looks like the circumference of the “O” in

Obtuse Marginal)

RC → PDA (the right hand writes on the palm pilot pda)

(I hope those little memory hints help.)

This appears in another portion of the book Learning thru repetition is

a time-honored teaching tool they say And they say it over and over for

Right Circumflex LAD

LAD LAD Circumflex

Circumflex

Right Right

2-Chamber

LAX

So let’s answer our question from the beginning Remember gunshot to segment 8? Look at your drawing Segment 8 is right in the middle of the anterior portion of the heart Kind of a bulls-eye if you will The anterior wall is the distribution of the LAD See how easy that was So he as a hole in his LAD! Quick, get a doctor!

At this point I should be able to shout out a segment, and you shout out

a coronary artery—and vice versa If not, go back to the beginning and start reading again And this time draw it out Lastly, I want to explain how some of the TEE planes relate to my 17 segment star If you draw some dashed lines in between the lines of the star, these represent the planes of the TEE probe in certain views The four-chamber view slices thru segments 3 and 6, for example Next is the two-chamber view with the plane going anterior to inferior Last is the ME long-axis cutting seg-ments 7 and 4 among others

I

A AS

Chapter 15 The 17 Segment Model 145

3 The patient from the beginning of the chapter gets better, gets a

gun and goes all gangster on his shooter for revenge He aims for

the LAD Does he hit segment 2 or 12?

ANSWERS

1 Quick draw your 17 segment model, and look at the back wall

Hmmm… must be 5

2 Quick draw your 17 segment model and it looks like 14 is lateral,

so it must be the circumflex

3 Quick draw your 17 segment model, and guess he is accurate and

hits 2 which is anterior

HYPOTENSION AND CAUSES OF

CARDIOVASCULAR INSTABILITY

REAL WORLD NOTE Let’s face it, cowboys and cowgirls, this is the real crux of

the whole deal with echo All the cool physics and gradients and Doppler stuff are

necessary for the test And if you’re going to do cardiac echo, you need to know all

the neato-frito valve details But as TEE gets more and more common, the day will

come when every single anesthesiologist or ICUologist will need to know at least

the basics of TEE to figure out what’s going on when a patient gets unstable

The TEE is the anticrash weapon of choice

When badness happens (and we’ve all seen it happen), you might not

have a Swan or CVP And even if you do, you’re still wrestling with

num-bers that tell you something, but not the whole picture You are left with a

set of numbers from which you infer, or hope, you have the picture

The TEE gives you the real picture, right now, no need for a leap of faith

Cahalan points out in the tapes and at the meetings that, even with only a

lit-tle TEE experience, most people can diagnose the most common problems

in mere minutes After all, when most patients go to caca, you want to know:

n Heart, full or empty?

n Ventricle, good or bad?

n Tamponade, yes or no?

For most problems, then, Cahalan gives us a nice, neat, easy-to-understand

and inherently obvious breakdown of the main causes of hypotension:

1 End-diastolic area decreased, ventricle contracting OK—You’re low

on volume The heart is empty, so fill it

2 End-diastolic area increased, ventricle contracting poorly—

You have a bad and already overfilled ventricle Fix whatever’s

causing the global hypokinesis (Get a blood gas! Don’t forget the

basic stuff!), and once you’ve fixed what you can fix, it’s time for

inotropes or ventricular support of some kind

3 End-diastolic volume normal or low, ventricle contracting well or

hyperdynamic—You have a problem with the volume not “going

where it’s supposed to go” Either the volume is all going out into

a vastly dilated circulatory tree (anaphylaxis with low systemic

CHAPTER

16 Assessment of Perioperative Events and Problems

Ricardo Martinez-Ruiz and Christopher J Gallagher

vascular resistance), or else some other channel is misrouting your good cardiac output (severe mitral regurg or aortic regurg, or a ventricular septal defect).

Full

Empty Diastolic area >18 cm 2

Diastolic area <10 cm 2

Midpapillary views

The first two are easy to see with a glance at the TEE The third is a little trickier, but you can augment your TEE findings with other stuff (Flushed appearance and wheezing going along with anaphylaxis; murmurs or fur-ther TEE views to find mitral regurg, aortic regurg, or a VSD.)

Then the final thing you want to know, “Tamponade, yes or no?”, is figure-outable with your basic search for a pericardial effusion plus the hemodynamics of tamponade

Pericardial effusion

Right cavities squeezed by effusion

Chapter 16 Assessment of Perioperative Events and Problems 149

If you take nothing else away from TEE (say you don’t want to bother

taking the TEE exam), if you at least know this, the differential for

hypo-tension, you will save somebody some day

CARDIAC SURGERY: TECHNIQUES AND

PROBLEMS

Assessment of Bypass and Cardioplegia

How the hell do you use TEE to assess bypass and cardioplegia? Got

me I have no clue what the Society of Cardiovascular Anesthesia folk

were thinking when they put this on their magical list

Let’s stretch a little and try to figure this one out

n Use your TEE to show that the heart is not beating at all—that

would mean the cardioplegia is working

n Use your TEE to see that the heart is not blowing up like a

basketball—that would tell you that the cannulae are flowing in the

right direction and there is not some catastrophic flow reversal

One thing is worth mentioning at this time Disconnect your echo probe

while on bypass That will allow the probe to cool down and prevent

esophageal burns And remember that you do need to disconnect the

probe, not just put the image on FREEZE Although the word FREEZE

implies a cool state of affairs, you have just frozen the image You haven’t

actually frozen the probe and turned it into a big Fudgecicle

Cannulas and Devices Commonly Used During

Cardiac Surgery

The main cannula you’ll be asked to visualize is the retrograde cannula

for cardioplegia First, you need to know where the coronary sinus is (the

site of the retrograde cannula)

To see the coronary sinus on TEE, you need to get your ME

4-cham-ber view and slowly advance the probe into the stomach and VOILA!!!

The coronary sinus shows up as a drak conduit that drains into the right

atrium (you can check with Doppler to see the coronary sinus blood

flow) Ocassionally you may have a valve (Thebesian valve) impeding

the easy positioning of the retrograde cannula, the cannula gets stuck

on it It is pretty cool to tell your surgeon that the reason he is struggling

getting it in position is because of the valve

Retrograde cannula

RA Coronary sinus Coronary sinus

Cannula to cross the threshold Like all cannulas, the retrograde cannula has a “double line” that tells you it’s a man-made thingamajig And like all cannulas, its 3-D reality will dive in and out of your 2-D picture, making

it sometimes a little tough to keep it entirely in view In some occasions you may see the stippled balloon at the end of the cannula: it looks like a star cluster (yes…use your imagination!)

What else might Show up During Cardiac Surgery?

The aortic cannula is hard to see as it is often placed far into the ing aorta, usually in the blind spot area

ascend-But anytime an aortic cannula is in, a dissection (heaven forbid) could occur, so you go ahead and examine the aorta and look for this dreaded complication

Look at the atrial cannula? Sure, why not? I suppose you could imagine looking at the venae cavae, if the surgeons were having trouble cannulat-ing, to see if there is a web or some bizarre thing holding them up

The tip of your dual stage cannula should be just into the IVC

Circulatory Assist Devices

It’s not a stretch to look for correct placement of an intra-aortic loon pump You want to see the tip of the IABP at the takeoff to the left subclavian artery No higher (occlusion to the left arm) and no lower (inadequate function of the balloon pump and potential occlusion of renal arteries, oops) You should see the tip of the IABP, but no bal-loon!, at the level of the takeoff of the Lt subclavian artery on the most upper view of the descending thoracic aorta As soon as you push the probe deeper, the balloon should be visible with its characteristic up and down, up and down… (you can also assess the quality of expan-sion of the balloon)

bal-Chapter 16 Assessment of Perioperative Events and Problems 151

Balloon and NO it

sc artery Desc aortic

SAX

Tip no balloon!

Further in

It sc artery

Things can get more exotic, of course

Left and right ventricular assist devices, and ECMO when things are

going really swell, all enter the cardiac realm in this Brave New World we

inhabit

With an LVAD, you want to make sure the person doesn’t have a patent

foramen ovale or interatrial septal defect You could, as the blood rushes

out of the left side into the assist device, “suck” blood from the right side

over to the left

If this happens, then no blood goes out the right side, so no blood goes

to the lungs, so no oxygen enters the body Unless your patient is a

cya-nobacterium, he or she will need oxygen

So check for these PFO when you start an LVAD You may also need to

make sure that there is no aortic regurgitation If that happens blood will

“recirculate” in a circle of death >>>> from the LV >>> to LVAD >>>> to

Once the LVAD is going, you can also use the TEE to confirm that the

aortic valve isn’t opening At first that concept seems a little jarring

“What, the aortic valve isn’t opening? But, golly Mr Wizard, how can the person live?”

Yes, usually that is the case, but remember, you’re not in Kansas more, Dorothy The LVAD is doing all the work now You want all the blood to leave the heart and go into the machine

any-In testville, remember that the cannula that is draining blood out of the body into the machine is the inflow cannula (That is, inflow as far as the machine is concerned You could get faked out and think, well, relative to the body, that is technically outflow, so… Don’t think that!)

There are two new gadgets for LV support that can be placed ously >> the Tandem heart and the Impella The Tandem inflow cannula goes from the femoral vein into the IVC into the RA and then goes through the interatrial septum into the LA! The LA blood is pulled into the centrifugal pump located outside the body to be reinfused into the arterial system via the femoral artery to provide systemic perfusion You can check the place-ment of the inflow cannula as it goes across the interatrial septum

percutane-Tandem cannula

Inflow LA SVC RA IVC

The impella is different: it consists of a very small impeller-based pump that its placed across the aortic valve (via the femoral artery most com-monly) and sucks blood out of the LV and propels it back into the aorta This will provide for overall systemic perfusion needs and will also let the

LV decompress and recover Neat stuff!!!

Aortic valve

Impella LVAD Outflow

Inflow

Chapter 16 Assessment of Perioperative Events and Problems 153

ECMO and RVADs? You can use TEE to check those cannulas too and

just make sure they seem to be in the right place

Intracavitary Air

No biggie here Air bubbles look like snowflakes swirling around in the

heart You will want to look for these (the TEE is the most sensitive at

detecting air bubbles) after an open-chamber procedure to make sure

you de-aired the heart properly

Air can hide out in the tangle of papillary muscles and chordae

tendin-eae (When you think of a cardiac “chamber,” you think of this big, open

space, but it’s damned crowded in there.) Check along the septum and

down in the apex for “lurking air”

Minimally Invasive Cardiopulmonary Bypass

(Perhaps more accurately called “Minimally done anymore

cardiopulmo-nary bypass”.)

As regular old off-pump CABGs work so well now, the days of MIDCABs

(such a puckish name) seem to be numbered TEE was used to make

sure the fantastically complicated tangle of cannulas was all in place

Thank God this ischemia-producing (in the anesthesiologist) procedure is

going the way of the 8-track cassette and the slide rule

Off-pump Cardiac Surgery

Now this is more like it

As a sign of the times, I looked back at the tapes for the 1999 TEE

course People then were talking about doing off-pump cardiac

sur-gery in “select cases” and doing relatively small percentages of people

off pump Well, of course, by now, everybody and their second cousin is

doing off-pump CABGs McDonald’s will have a drive-thru window soon

where you can get off-pump CABG done

One pain in the ass, actually THE pain in the ass, with off pumps is “the

hike”—when the surgeons lift the heart to get at those dim and distant

distals Hemodynamically the patient’s blood pressure often takes a

hit with the hike, though the newer “holder thingies” and more surgeon

experience have made the whole process less devastating than in days

of yore The hike also goofs up the echo, because now you may have air

between the heart and the probe

No can do the transgastric view, no way

Hike the heart, the view goes away

The whole deal during off-pump surgery is, “Can we do this off pump?”

or “Are things getting SO BAD that we have to stop this charade, put in cannulas, and do this on pump?” Pertinent to us is the question, “Can the TEE help me make that decision?”

What tells you things are going to the dogs?

n Low blood pressure unresponsive to your usual blandishments

n Ectopy so bad that you get ectopy

n Ditto asystole

n Rising CVP or PA pressures

n Increasing mitral or tricuspid regurgitation

n Regional wall motion abnormalities that persist and persist and (when the hell are they going to finish the graft!?) finally make you and everybody panic and say, “BASTA! The patient’s dying! Stop!”.But during off-pump cases, you are actually looking at the wall right there, with your own eyeballs Even “hard to see” walls are hiked up for you and the surgeon and everyone to see You can, of course, confirm it with the TEE, but your eyeballs do just as well in the OR

TEE helps you to see the mitral and tricuspid regurg, of course (Unless you’re Superman, most of us can’t see inside the heart.)

So how much and how long of a wall motion abnormality is enough to push you “onto the pump”?

Uh…Jack Shanewise gives this talk at the TEE conference (He’s a great speaker, so don’t miss him Remember, he spearheaded the big paper that gave us the “big 20” views, so he knows from TEE.) He tells us he usually sees signs of ischemia or wall motion abnormalities during these off-pump cases, but that as long as things improve after the anastomosis

is complete, you’re usually (not always) OK

Having heard the talk and done a bunch of off-pump cases, you’re still left with a bit of a “by guess and by God” feeling about these off-pump cases:

1 They hike the heart

2 They clamp the vessels to sew in the graft

3 Things get bad, you limp along with volume, a little Neo maybe, you hope things don’t get too bad

4 TEE confirms that you are limping along, but you hope things get better

5 Things either get better or they don’t

6 If they don’t, if the wall motion abnormality does NOT go away, then you have to reexamine that graft and make sure it’s working OK (If you had an on-pump case and had a new regional wall motion abnormality, you would reinvestigate your graft, wouldn’t you?)

Chapter 16 Assessment of Perioperative Events and Problems 155

How’s that for the state of the art?

I tell residents an off-pump case is like a labor epidural that’s just kind

of, sort of working You pray and pray for the lady to deliver so that you’ll

just be done with it! Same with these cases: you pray and pray that they

get the grafts done so you’ll just be done with it!

CORONARY SURGERY: TECHNIQUES AND

ASSESSMENT

How will TEE help you in an on-pump CABG? (Since we talked about

off-pump just a second ago.)

Pretty much, the TEE will replace the Swan (This debate will swirl around

for a long time, particularly the “What happens when the patient goes

to the ICU; do we put a probe in again each time we get in trouble? You

guys have it in the whole time in the OR, but we in the ICU don’t!”.)

With the TEE going in nearly all our patients (people at the meeting

con-firmed that, in a lot of places, heart surgery means a TEE, period), you

get most of your “Swan-like” information right there from the TEE (We do

put introducers in everybody, so we can always put a Swan in later.)

n Heart empty or full? TEE tells us

n Ventricle crummy, ventricle snappy? TEE tells us

n Tamponade? TEE tells us

In effect, this discussion is the exact same discussion as in Hypotension

and Causes of Cardiovascular Instability above What, after all, are you

concerned about during a CABG? Hypotension and cardiovascular

insta-bility So, boom, same exact analysis

This helps you out at all points of the case Hypotension and

cardiovas-cular instability can and do happen whenever they want to—at induction,

during the IMA dissection, coming off pump, whenever

TEE also helps in regional wall motion abnormality analysis This goes

right back to another previous discussion in Chapter 14 (see Coronary

Artery Distribution and Flow)

Examine the patient ahead of time, look for wall motion abnormalities

See which grafts go in which distribution If you see a new wall motion

abnormality, that is evidence a graft is not working

This comes in especially handy once the chest is closed The skin and

sternum are “in the way” and the TEE helps you see what your eyes no

longer can

VALVE SURGERY: TECHNIQUES AND ASSESSMENT

Valve Replacement: Mechanical, Bioprosthetic, and Other

Not to sound like a broken record here, but TEE helps you during valve surgery the same way it helps you during CABGs, that is, in the evalua-tion of cardiac function and volumes, the management of hypotension and cardiovascular instability

TEE helps you keep the blood going round in circles in your patient, and

Oh be Joyful to that How?

n Heart empty, heart full?

n Ventricle good, ventricle bad?

n Tamponade, yes or no?

Do we see a pattern here?

But in valve surgery, we go a little further than management of tension and cardiovascular instability We look at the valve itself, before surgery, to confirm the diagnosis and assess severity, and after surgery,

hypo-to confirm good function of the valve and make sure there aren’t any problems And yes, once all is done, we go back like dutiful soldiers to evaluating for hypotension and cardiovascular instability

TEST NOTE You’ve got a little memorizing to do You will need to know what different valves look like on echo Not the end of the world, but the hyphenated double names of the artificial valves drove me cuckoo Doesn’t any one person ever design a valve?

Let’s plow through the various kinds of valves and how they look Different ones have different jets of regurg (you’ll need to know that too), but one thing holds true for all valve replacements You should not see a PERI-valvular leak You shouldn’t see leaking OUTSIDE the sewing ring That means bad news All valves have some leaking INSIDE the sewing ring, but not, repeat not, outside

Another goody to know: prosthetic valves all need anticoagulation, tissue valves don’t Now, on to the specific valves

NOTE get all the valve pics and make them smaller and put them together in one pic

Starr-Edwards

Ball-in-cage

Chapter 16 Assessment of Perioperative Events and Problems 157

Oldest kind, can last a long time

Kind of big and clunky, causes a lot of hemolysis

Since flow goes around the sides, that’s where you’ll see a couple of jets

of regurg before the valve closes (All valves have a little bit of regurg

before they close.)

Medtronic-Hall and Björk-Shiley

Tilting disc

Complex flow pattern

St Jude and Carbomedics

(Always these double names! At least they settled on just one saint for

the St Jude.)

Bi-leaflet, metallic >>> easy to see leaflet movement These leaflets

can get stuck (by clot or tissue) and will produce severe MR

Great durability, need anticoagulation

They have signature regurgitant jet pattern to reduce clot formation

LA

LV

Bileaflet mechanical prosthesis signature jets

Hancock and Carpentier-Edwards

(This really ticks me off, we already have a Starr-Edwards!)Porcine bioprosthesis They are getting better and better durability, usually no need for long-term anticoagulation

Has three metallic stents holding it in place, so you still see shadows.They do have a built-in small central regurgitant jet

ROSS PROCEDURE

Take out the diseased aortic valve, take out the native pulmonic valve, put the pulmonic valve in the aortic place, put a tissue graft in place of the pulmonic valve

TEST NOTE For me, the shadows from the tissue valve stents and the shadows from the prosthetic valves can look pretty similar Watch the video of this or study the CD movies of these a lot because, on the test, you only have a minute or so to look at these, and it can be pretty confusing If there is one area where you can get fooled, this is it

There are stentless prosthetic valves You won’t see the metal and their reflections, but you may see a sewing ring That is an extremely subtle finding and easy to miss

Chapter 16 Assessment of Perioperative Events and Problems 159

An issue with tissue valves is longevity They tend to wear out faster

You can measure gradients across these valves, but it can be

challeng-ing You have to know where the tight spots are and you have to

navi-gate a straight shot through that spot For example, for a Starr-Edwards,

you’ll have to slip your Doppler right through one of those regurgitant jets

around the sides of the ball

A useful “Internal Medicine-y” thing to know about gradients: when you

are evaluating a valve and see a gradient you think is a little high,

remem-ber, all valves have some gradient Try to find an old reading of the

gradi-ent before you ring the alarm bells The thinking is the same as getting an

old ECG or CXR for comparison

All valves are subject to embolism and endocarditis So you’ll be

look-ing through some confuslook-ing reflections (try different angles to avoid the

metallic shadow) as you hunt for fistulas, abscesses, and clots

VALVE REPAIR

Aortic Repair?

Doesn’t happen too often A truly isolated injury to one cusp, maybe, but

surgeon enthusiasm for aortic valve repairs has faded a bit of late More

often they replace the aortic valve

Mitral Repair?

Now you’re talking This is becoming to cardiac surgeons what

appen-dectomy is to the general surgeon

First, you evaluate the mitral valve, looking to grade the severity

Four-plus regurg pretty much mandates that “something be done,” often

a repair rather than a replacement How do you know it’s 4+? Look for

systolic flow reversal in the pulmonic vein; that is

diagnostic/pathogno-monic/for sure for sure, good buddy, that the regurg is severe

Pulmonary Vein Flow

Systolic reversal: grade IV MR

Systole Diastol

e

Atrial reversal

After the repair is done, you will look at the mitral valve again, making

sure, well, that the repair worked! Regurg gone (good), but not so gone

that you have moved all the way to mitral stenosis (not good)

Tricuspid Repair?

If the tricuspid valve has severe regurg, you will see reversal of flow in the hepatic veins (Similar to seeing systolic flow reversal in the pulmonic vein with mitral regurg.) The surgeon may choose to repair it, though they

do this a lot less than mitral repairs

After the repair is done, look for enough repair to stop the regurg (good), but not so much that you have stenosis (not good) Sound familiar?

TRANSPLANTATION SURGERY Heart

As far as TEE is concerned, there are only a few special things you’ll see with a heart transplant You’ll see extra-atrial tissue and see suture lines that demarcate “the new from the old”

From an anesthesia standpoint, one thing you will really be watching for

is signs of right heart failure—the big bugaboo of heart transplants What will you see, by way of review?

n RV enlargement

n Tricuspid regurg

Of course you look for all the usual suspects—hypovolemia, global function, tamponade—as in every patient Air, too, can bite you in the butt, but it’s the right heart battling against “previously unseen” pulmo-nary hypertension that will cause the most headaches

dys-Watch that RV!

Lung

Most lungs are, you sincerely hope, full of air, so it’s a toughie to ine them with TEE Unless the lung is consolidated you might be able to

exam-Chapter 16 Assessment of Perioperative Events and Problems 161

“see” the parenchyma > bad thing Also with big pleural effusions you

can see the lung “floating” in the descending thoracic aortic views You

can also see the presence of clot and fibrin in the fluid (pretty cool)

Pleural effusion Lung

Aorta

So in those rare cases of lung transplants (not done too often or in too

many places), you’re left with doing the usual stuff—monitoring the heart

for signs of failure

You will yawn when I say this, but you’ll be looking to monitor for

hypo-tension and cardiovascular instability; that is, you’ll watch for:

n Ventricle full or empty?

n Ventricle good or bad?

If you put the TEE deep and turn it around, you can look at the liver,

though I don’t know of many observations you can make (None were

mentioned at the meeting, or in the tapes or any books I read.)

I’ve been called into liver transplantation surgeries to put the TEE in and

look around Of note, the varices that most of these patients have are

NOT a contraindication to placement of the probe

You might want to take a look at the IVC as an index of fluid status and

Rt heart function>>IVC >2 cm in diameter suggests fluid overload (also

the lack of collapse with inspiration will confirm this)

1 When placing an LVAD you should look for, except:

A Patent foramen ovalis

D Inferior vena cava

3 The mitral regurgitant jet of a bioprosthesis is, except:

A Central

B The severity is trace to mild

C Is a washout jet to avoid clot formation

D Comes from outside the ring

4 In the case of an anaphylactic shock the heart is/has:

A Empty

B Hyperdynamic

C Low end systolic area in TG views

D All of the above

5 In order to assess for contractility in an off pump CABG, you should, except:

A Wait for the surgeon to “drop” the heart

B Look at the operative field to see how the heart is contracting

C Use your filing pressures

D The air behind the heart as it is elevated will interfere with the echo image