Case Studies In Small Animal

Cardiovascular Medicine

Case 2

M-mode echocardiograms

This M-mode echocardiogram shows normal left ventricular (LV) diastolic wall thicknesses, a larger than normal left ventricular end-diastolic diameter (6 cm; normal = 4.5 cm) and a larger than normal left ventricular end-systolic diameter (5.2 cm; normal = 3 cm).  PL. EFF = Pleural Effusion

The E-point to septal separation (EPSS) is increased to 17.5 mm (normal is less than 6 mm in this dog). The excursions of the mitral valve on an M-mode echocardiogram are labeled A through F. E is the maximum excursion or opening of the mitral valve that occurs during rapid ventricular filling in early diastole. The EPSS is a measure from this maximum opening of the mitral valve on the M-mode echocardiogram to the interventricular septum. When left ventricular function is depressed, forward (into the aorta) stroke volume in systole may be decreased and so the amount of blood replacing it through the mitral valve in diastole may be decreased. The mitral valve is a passive structure and so if less blood flows through it, it will not open as far. Consequently, the distance between the maximal opening and the interventricular septum is increased. The increase in left ventricular chamber size also contributes to the increase in EPSS. LV = Left Ventricle

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©Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.