Mitral annular area in systole – Medicine MCQ

Mitral annular area in systole:
a) Decreases by 10%
b) Decreases by 25%
c) Increases by 10%
d) Increases by 25%

Correct answer: b) Decreases by 25%

In systole, when the ventricle contracts, the mitral annulus also contracts, reducing the mitral annular area by about 25% [1]. This is important in preventing mitral regurgitation in systole. When the left ventricle is dilated, with associated annular dilatation, even in the absence of valvular damage, mitral regurgitation can occur. Similarly, when the left ventricular systolic function is poor, the decrease in mitral annular area with systole is reduced, paving the way for mitral regurgitation.

Reference:
1. Orniston JA, Shah PM, Tei C, Wong M. Size and motion of the mitral valve annulus in man. I. A two-dimensional echocardiographic method and findings in normal subjects. Circulation 1981; 64: 113-20.