Causes

Your heart has four valves that keep blood flowing in the correct direction. These valves include the mitral valve, tricuspid valve, pulmonary valve and aortic valve. Each valve has flaps (leaflets or cusps) that open and close once during each heartbeat. Sometimes, the valves don't open or close properly, disrupting the blood flow through your heart to your body.

In mitral valve disease, the mitral valve between the upper left heart chamber (left atrium) and the lower left heart chamber (left ventricle) doesn't work properly. It may not be closing properly, which causes blood to leak backward to the left atrium (regurgitation), or the valve may be narrowed (stenosis).

Mitral valve disease has many causes. Some forms of mitral valve disease can be present at birth (congenital heart defect).

Mitral valve regurgitation can be caused by problems with the mitral valve, also called primary mitral valve regurgitation. Mitral valve regurgitation is often caused by mitral valve prolapse, in which the mitral valve flaps (leaflets) bulge back into the left atrium. Diseases of the left ventricle can lead to secondary mitral valve regurgitation.

Mitral valve stenosis is often caused by rheumatic fever, which is a complication of a strep infection that can affect the heart.