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 regurgitation, the valve between the upper left heart chamber (left atrium) and the lower left heart chamber (left ventricle) doesn't close tightly, causing blood to leak backward into the left atrium (regurgitation).

Mitral valve regurgitation causes

Mitral valve regurgitation can be caused by problems with the mitral valve, also called primary mitral valve regurgitation. Diseases of the left ventricle can lead to secondary or functional mitral valve regurgitation.

Possible causes of mitral valve regurgitation include:

• Mitral valve prolapse. In this condition, the mitral valve's leaflets bulge back into the left atrium during the heart's contraction. This common heart defect can prevent the mitral valve from closing tightly and lead to regurgitation.
• Damaged tissue cords. Over time, the tissue cords that anchor the flaps of the mitral valve to the heart wall may stretch or tear, especially in people with mitral valve prolapse. A tear can cause leakage through the mitral valve suddenly and may require repair by heart surgery. Trauma to the chest also can rupture the cords.
• Rheumatic fever. Rheumatic fever — a complication of untreated strep throat — can damage the mitral valve, leading to mitral valve regurgitation early or later in life. Rheumatic fever is now rare in the United States, but it's still common in developing countries.
• Endocarditis. The mitral valve may be damaged by an infection of the lining of the heart (endocarditis) that can involve heart valves.
• Heart attack. A heart attack can damage the area of the heart muscle that supports the mitral valve, affecting the function of the valve. If the damage is extensive enough, a heart attack can cause sudden and severe mitral valve regurgitation.
• Abnormality of the heart muscle (cardiomyopathy). Over time, certain conditions, such as high blood pressure, can cause your heart to work harder, gradually enlarging your heart's left ventricle. This can stretch the tissue around your mitral valve, which can lead to leakage.
• Trauma. Experiencing trauma, such as in a car accident, can lead to mitral valve regurgitation.
• Congenital heart defects. Some babies are born with defects in their hearts, including damaged heart valves.
• Certain drugs. Prolonged use of certain medications can cause mitral valve regurgitation, such as those containing ergotamine (Cafergot, Migergot) that are used to treat migraines and other conditions.
• Radiation therapy. In rare cases, radiation therapy for cancer that is focused on the chest area can lead to mitral valve regurgitation.
• Atrial fibrillation. Atrial fibrillation is a common heart rhythm problem that can be a potential cause of mitral valve regurgitation.