Segmental Left Ventricular Systolic Function

Published on 06/02/2015 by admin

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Segmental Left Ventricular Systolic Function

John C. Sciarra and Christopher J. Gallagher

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 segments 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.

image

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.

Pictures tell it all:

image

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 wonder 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 abnormalities 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:

Golly.

All of this high-tech ranking is groovy, but you just have to look at a bunch of echos and try to peg, “Which wall is not happening?”. This can be harder than it seems, so be systematic about it. Look at one section and (this according to the great Cahalan himself) say, “Systole, systole, systole” and see if that particular section moves.

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 “moving picture experience”, for there is no other way than to drill these. On the tapes from the 2002 meeting, they recorded the “Regional Wall Motion Unknown” session. That is the best way I found to practice picking out the “mystery wall motion abnormality.” (Quit laughing as I mention “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:

Whatever it may have been, when you see a new wall motion abnormality that you thought you should have fixed, take a look-see.

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 aesthetically 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.

Questions

1. Regarding myocardial stunning:

2. Concentric LV hypertophy is:

3. Eccentric LV hypertophy is:

Answers

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