Mitral stenosis is a narrowing of the mitral valve in the heart. This valve is located between the upper chamber and the lower pumping chamber of the left side of the heart. Blood must flow from the atrium, through the mitral valve, and into the ventricle before being pumped out into the rest of the body. Mitral stenosis results in poor blood flow between the two left chambers, so not enough blood and oxygen is pumped throughout the body.

Mitral Valve Stenosis
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The most common cause of mitral stenosis is rheumatic fever, which scars the mitral valve. A less common cause is a congenital defect, usually part of a complex of multiple heart defects present at birth. Very rare causes include infectious endocarditis, blood clots, tumors, or other growths that block blood flow through the mitral valve.