Mitral valve Mitral valve The mitral valve (), also known as the bicuspid valve or left atrioventricular valve, is a valve with two flaps in the heart, that lies between the left atrium and the left ventricle. The mitral valve and the tricuspid valve are known collectively as the atrioventricular valves because they lie between the atria and the ventricles of the heart. In normal conditions, blood flows through an open mitral valve during diastole with contraction of the left atrium, and the mitral valve closes during systole with contraction of the left ventricle. The valve opens and closes because of pressure
Mitral insufficiency subsequent displacement of the papillary muscles and the dilatation of the mitral valve annulus. Rheumatic fever (RF) and Marfan's syndrome are other typical causes. Mitral valve stenosis (MVS) can sometimes be a cause of mitral regurgitation (MR) in the sense that a stenotic valve (calcified and with restricted range of movement) allows backflow (regurgitation) if it is too stiff and misshapen to close completely. Most MVS is caused by RF, so one can say that MVS is sometimes the proximal cause of MI/MR (that is, stenotic MI/MR) and that RF is often the distal cause of MVS, MI/MR, or both.