Some people with mitral valve disease might not experience symptoms for many years. Signs and symptoms of mitral valve regurgitation, which depend on its severity and how quickly the condition develops, can include:

• Abnormal heart sound (heart murmur) heard through a stethoscope
• Shortness of breath (dyspnea), especially when you have been very active or when you lie down
• Fatigue
• Heart palpitations — sensations of a rapid, fluttering heartbeat
• Swollen feet or ankles

Mitral valve regurgitation is often mild and progresses slowly. You may have no symptoms for many years and be unaware that you have this condition, and it might not progress.

Your doctor might first suspect you have mitral valve regurgitation upon detecting a heart murmur. Sometimes, however, the problem develops quickly, and you may experience a sudden onset of severe signs and symptoms.

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.

Several factors can increase your risk of mitral valve regurgitation, including:

• A history of mitral valve prolapse or mitral valve stenosis. However, having either condition doesn't necessarily mean you'll develop mitral valve regurgitation. A family history of valve disease also can increase risk.
• A heart attack. A heart attack can damage your heart, affecting the function of the mitral valve.
• Heart disease. Certain forms of heart disease, such as coronary artery disease, can lead to mitral valve regurgitation.
• Use of certain medications. People who take drugs containing ergotamine (Cafergot, Migergot) and similar medicines for migraines or who take cabergoline have an increased risk of mitral regurgitation. Similar problems were noted with the appetite suppressants fenfluramine and dexfenfluramine, which are no longer sold.
• Infections such as endocarditis or rheumatic fever. Infections or the inflammation they cause can damage the mitral valve.
• Congenital heart disease. Some people are born with an abnormal mitral valve prone to regurgitation.
• Age. By middle age, many people have some mitral valve regurgitation caused by natural deterioration of the valve.

When it's mild, mitral valve regurgitation usually does not cause any problems. However, severe mitral valve regurgitation can lead to complications, including:

• Heart failure. Heart failure results when your heart can't pump enough blood to meet your body's needs. Severe mitral valve regurgitation places an extra strain on the heart because, with blood pumping backward, there is less blood going forward with each beat. The left ventricle gets bigger and, if untreated, weakens. This can cause heart failure.

Also, pressure builds in your lungs, leading to fluid accumulation, which strains the right side of the heart.

• Atrial fibrillation. The stretching and enlargement of your heart's left atrium may lead to this heart rhythm irregularity in which the upper chambers of your heart beat chaotically and rapidly. Atrial fibrillation can cause blood clots, which can break loose from your heart and travel to other parts of your body, causing serious problems, such as a stroke if a clot blocks a blood vessel in your brain.
• Pulmonary hypertension. If you have long-term untreated or improperly treated mitral regurgitation, you can develop a type of high blood pressure that affects the vessels in the lungs (pulmonary hypertension). A leaky mitral valve can increase pressure in the left atrium, which can eventually cause pulmonary hypertension. This can lead to heart failure on the right side of the heart.