We previously discussed about the mitral valve M-mode in PLAX view and E-point septal separation (EPSS). EPSS is the distance between peak of the E-wave (early diastolic wave) of the mitral tracing and interventricular septum. Elevated EPSS is a sign of LV systolic dysfunction. See the following infographic and illustration of the normal mitral M-mode.

One of the limitations of EPSS or depending exclusively on mitral valve excursion to estimate LV systolic function is that it is influenced by aortic regurgitation. The regurgitant jet will limit the mitral leaflet movement during diastole, reducing the EPSS (= false impression of low LV ejection fraction). Here is an M-mode image obtained from a patient with moderate aortic regurgitation. Note how anterior mitral valve leaflet appears to be shivering in diastole; this is due to aortic regurgitant jet impeding its movement. This phenomenon is also called ‘fluttering’ of the mitral valve. Similar appearance can sometimes be seen in atrial fibrillation. In such cases, you will also note irregularly spaced E waves (due to irregular heart rhythm) and fluttering in both the mitral leaflets (anterior and posterior).

Below are the apical 5 chamber and parasternal long axis (PLAX) views demonstrating aortic regurgitation on color Doppler. Also note mitral annular calcification. Illustrations of these views included showing the aortic valve location in case you need a refresher. On PLAX view, LV walls are thickening and coming closer but EPSS decreased, falsely suggesting low EF.

Below is color M-mode image obtained from the same patient. It superimposes the color Doppler with M-mode = easier to appreciate the timing of the turbulence (regurgitation).

Why should I know this? Because even before putting the color, you’ll know that the EPSS is not trustworthy in such cases.