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Assessment of LV function in critical illness

As the biggest and strongest chamber in the heart, the LV plays a key role in cardiac physiology. In approaching the critically ill patient, accurate assessment of the LV can help clinch a diagnosis, direct investigations/therapy, or expedite consultation. Thea ability to quickly assesses the left ventricle is an asset to critical care practitioners and patients alike, in helping to understand complex clinical problems. 

The following tutorial below will outline gross visual assessment of LV function.

Obtaining key views

First, you must obtain at least 2 key views of the LV to perform a informed visual assessment. While one view may suggest an abnormality (or lack thereof), two views are necessary to confirm. It is even better if these views are 90 degrees (orthogonal) to each other (parasternal long axis and short axis). Finally, ensure the endocardium is clearly seen, as otherwise, it can be exceptionally difficult to assess for thickening.

Assessment of LV function

The concept of assessing LV function requires you to visually gauge LV cavity changes in diastole and systole. While mathematical methods can be used (e.g. Simpson’s method or methods of disks), visual assessment can offer a high degree of correlation and is often the default method of choice in many echo labs. We advocate for some basic visual rules which can help the observer grossly categorize LV function.

Myocardial thickening & excursion

When the LV contracts its walls thicken and move inwards in unison to eject blood (if normal conduction). The walls will thicken roughly ~40% compared to its normal thickness. Further, as these walls thicken, the endocardium will move inwards (endocardial excursion). Visual assessment requires an attentiveness to both, as a wall may simply move inwards (have excursion), but not thicken (and vice versa).

EPSS

The E-point septal separation describes the distance from the anterior mitral valve leaflet to the ventricular septum in early diastole (E-phase).  You can see in this clip, M-mode is positioned through the septum and mitral valve. A normal EPSS is < 1cm (measured on M-mode), which has a high sensitivity for abnormal LV ejection fraction. An EPSS <1 cm is very unlikely to be accompanied by abnormally functioning LV. There are a number of caveats to EPSS (e.g. mitral stenosis, regional wall motion abnormalities), so EPSS should not be relied upon in isolation.

Gross categorization

While there are explicit methods to analyze ventricular function, we advocate for gross categorization based on visual assessment. While we recommend comprehensive echocardiography for exact EF calculations, visual assessment by a trained (“non-expert”) observer can have a significant impact on patient care. LV categories fall into the following schema:

HYper-dynamic LV function

A hyper-dynamic ventricle has an ejection fraction that exceeds 70%. In this short axis clip, you can see a hyper-dynamic ventricle (image left)  has almost no blood volume at end-systole and may have end-systolic occlusion of the papillary muscles. Now this can happen with profound hypovolemia (..of multiple causes) but can also occur with very low systemic vascular resistance.

References

Hope MD, De la Pena E, Yang PC, Liang DH, McConnell M V., Rosenthal DN. A Visual Approach for the Accurate Determination of Echocardiographic Left Ventricular Ejection Fraction by Medical Students. J Am Soc Echocardiogr. 2003;16:824–31. 

Labovitz AJ, Noble VE, Bierig M, Goldstein SA, Jones R, Kort S, et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American Society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr [Internet]. 2010 Dec;23(12):1225–30. Available from: 

​Lang RM, Badano LP, Victor MA, Afilalo J, Armstrong A, Ernande L, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: An update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr [Internet]. 2015;28(1):1-39.e14.

Melamed R, Sprenkle MD, Ulstad VK, Herzog CA, Leatherman JW. Assessment of left ventricular function by intensivists using hand-held echocardiography. Chest [Internet]. 2009;135:1416–20.​

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