The mitral valve (MV) (or bicuspid valve ) is one of the four cardiac valves. It is the atrioventricular valve that allows blood to flow from the left atrium to the left ventricle. It opens during diastole and closes during systole. Gross anatomy... Learn about the mitral valve , one of the heart’s four valves that prevents blood from flowing backward. Find out how it works, what conditions can affect it, and how to prevent mitral valve disease. Learn about the mitral valve , one of the four heart valves that lies between the left atrium and the left ventricle. Find out its structure, function, and common disorders such as regurgitation and stenosis. Learn about the types, causes, risk factors, and symptoms of mitral valve disease, a condition affecting the heart valve between the left atrium and ventricle. Find out how to diagnose and treat this disease with medication, surgery, or other interventions.