Left Ventricular Systolic Function

Chapter 13


Left Ventricular Systolic Function



Eric W. Nelson


For some reason there is a lot of focus on the left ventricle and its evaluation 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 football, 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?




image


image


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 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 area


You 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 determine 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 transgastric 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.




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!


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.


Related posts:

  1. The Yellow Brick Road
  2. The 17 Segment Model
  3. Principles of Doppler Ultrasound
  4. Pericardium and Extra-Cardiac Structures: Anatomy and Pathology

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Jun 4, 2016 | Posted by in CARDIOLOGY | Comments Off on Left Ventricular Systolic Function

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