Cardiac Anatomy

Christopher J. Gallagher and John C. Sciarra

Time to go back to the model and the pie-shaped slice of imaging that comes out of the echo probe.

And time to take another good look at a plastic model of a heart.

These imaging planes tie in with the BIG 20 views of the heart. These are the 20 views detailed in THE ARTICLE by Shanewise et al on echo.¹ The 20 views are also detailed a million times over on different internet sites. Google “University of Toronto: TEE” for a great tutorial. This article and the 20 views detailed therein are the absolute crux of the TEE experience. Photocopy those 20 views and tape them to your TEE machine. Every time you examine a patient, try to get all the 20 views. Get in the habit of “examining everything every time”. If not, you’ll just look at the “thing of interest” and you’ll miss something else.

Also, getting all 20 views will sharpen your TEE probe-wiggling skills. Shanewise gives the lecture on the “standard exam”—meaning the 20 views—and he says he can do it in 7 minutes, before the patient is even draped!

Shanewise has thrown down the gauntlet. Can you do it that fast?

Here is our version of the 20 views. Notice it is not labeled. That is your job. As you read through this book label every structure on these 20 images. Yes, you can write on the book. You did buy your own, didn’t you?

In each view, note the approximate omniplane angle!

The imaging planes for these views are divided into distinct “layers,” though, in reality, you slide gradually from one view to another rather than making jerky quantum leaps.

The planes are upper esophageal, midesophageal, transgastric, and deep transgastric. Each plane takes in a few views, except for the pesky deep transgastric, which takes in just one view.

Here’s your new alphabet:

Go over these views in detail. Know how to express your findings as related to the views, for example:

That’s how you want to work with the “TEE Alphabet”.

The four-chamber view gives you your best “initial impression” and a good look at most of the major stuff in the heart. It’s what you first see when you’re just starting TEEology.

When you show this view, most medical people can immediately grasp what’s going on because it looks like a drawing of the heart. If you have a med student, ICU nurse, surgeon, or someone else looking on, this view shows you all four chambers of the heart (hence the name), the lateral and septal walls, and the mitral and tricuspid valves. What a deal!

And, niftier still, if you just rotate the view 90 degrees, you get the two-chamber view and see the inferior and anterior walls. Rotate 90 more degrees, and you get the long-axis view, revealing the anteroseptal and posterior walls. Voila! You’ve seen all the walls of the heart.

As time passes, you’ll get to know what each view can “do” for you.

Now go transgastric, and you see all this stuff in cross section.

This systematic look at the walls of the heart will help us later when we study coronary anatomy. (Preview: By knowing which wall you’re looking at and which coronary feeds it, you can tell which coronary vessel is not working. Ischemia leads to wall motion abnormalities and bingo! You, Sherlock Holmes, MD, will nail the diagnosis.)

Knowing which wall is which seems a little tough at first, but a little brutal memorization early on will pay off handsomely later.

Need a little crutch? Try this. Draw a cross section first and get those walls down. Then, draw lines connecting each to its opposite wall. That will get you to link these walls in pairs and keep you from getting mixed up.

We will break these walls down further into segments later on, in (Segmental Left Ventricular Systolic Function) of this outline. But before you can know the wall segments, you need to know the walls themselves, so work on just that for now.

Back to Med School for a minute.

All valves have three leaflets except the mitral valve, which has two.

Too simple for you? Believe it or not, it’s worth reviewing because, in a test or in a hairy case, you can and do get amped out and go, “Wait, that’s the…uh…”.

It is comforting to know that there is nothing we are incapable of forgetting.

Again, this is Med School redux, but it’s worth rehashing to make sure you have it all down ice cold.

Break it down into sections. Since it’s a “cycle”, you can start wherever you want.

Let’s start at the P wave of the EKG.

Atrium contracts, blood flows through the mitral valve into the left ventricle. And on the right side? Atrium contracts there, too, and blood flows from the right atrium into the right ventricle. Is more going on? Well, yes. There is some backward flow into the pulmonary veins at the time of atrial contraction, too. And on the right side? Does it make sense there might be a little backward flow there too? (There are, after all, no valves to prevent it.) Yes, by golly, there is a little backward flow there, too, into the two “feeders” of the right atrium, the inferior and superior venae cavae. Should there be a little backward flow down the coronary sinus? That, too, lacks any valves to prevent backward flow. My guess (I never read this or heard it mentioned in any lecture) is yes.

God all fishhooks, Batman, all that going on just with the stupid P wave. I thought this section would be simple!

On to the QRS complex.

First, recall how the electricity travels through the ventricle.

As the ventricle depolarizes, the ventricle contracts, slamming the mitral and tricuspid valves shut, and opening the aortic and pulmonic valves.

Oh, that was easy, not nearly so complex as that damned P wave.

Now, the ST segment.

After the ventricles are done contracting, the aortic and pulmonic valves close, and the ventricles continue to relax (isovolumic relaxation) until the pressure falls so low that the mitral and pulmonic valves can open and start filling the ventricles.

That’s what goes on with the heart itself. It’s worth taking a second look at this stuff. This time we’ll look at the CVP and the SGC and review what goes on and when.

All those descents and letters and stuff are a pain in the ass, no doubt. (Sort of like the Kreb’s cycle; you memorize it a few times in school, then promptly forget it after the test.) But, alas, the docs giving the TEE review course went over these more than once, so it looks like you have to learn it again.

What makes this interesting, of course, is when things go wrong. Regurg, stenosis, congenital malformations, all kinds of things can throw that waveform off. But you have to know the normal wave to make sense of the abnormal.

Answers