Mitral regurgitation is the most common type of heart valve insufficiency. Any disorder that weakens or damages this valve can prevent it from closing properly, causing this type of leakage. Mitral regurgitation becomes chronic when the condition persists rather than occurring for only a short time period.

When the mitral valve fails to close properly, blood flows back to the left atrium from the left ventricle. The blood flow to the body (cardiac output) is decreased as a result, so the heart pumps harder to try to compensate.

Chronic mitral regurgitation affects approximately 6% of women and 3% of men, but after 55 years of age, some degree of mitral regurgitation is found in almost 20% of men and women who undergo echocardiograms.

Congenital (present from birth) mitral regurgitation is rare if it is not part of a more complex heart defect or syndrome. Mitral valve prolapse, which involves weakening and ballooning out of the valve and affects about 5% of the population, is a relatively common cause of chronic mitral regurgitation.

About one-third of all cases of chronic mitral regurgitation are caused by rheumatic heart disease, a complication of untreated strep throat that is becoming less common. Rheumatic heart disease can lead to thickening, rigidity, and retraction of the mitral valve leaflets

Chronic mitral regurgitation can also be caused by disorders such as atherosclerosis, hypertension (high blood pressure), left ventricular enlargement, connective tissue disorders such as Marfan's syndrome, other congenital defects, endocarditis (infection of the heart valve), cardiac tumors, or untreated syphilis (rare). Acute mitral regurgitation may become chronic.

Risk factors include an individual or family history of any of the disorders mentioned above and use of fenfluramine or dexfenfluramine (appetite suppressants now banned by the FDA) for four months or longer.

• fatigue, exhaustion, and light-headedness (may result from low cardiac output)
• palpitations (related to atrial fibrillation)
• cough
• shortness of breath
  • with exertion (exertional dyspnea)
  • when lying down (orthopnea)

• urination, excessive at night

Palpation may show thrill (vibration) over the heart. A stethoscope examination of the heart reveals a distinctive murmur. Rales (a crackly sound) or other abnormal breath sounds may be heard on lung examination. Ankle swelling, enlarged liver, distended neck veins, and other signs consistent with right-sided heart failure may be present.

An enlarged left atrium with a thickened or deformed mitral valve, and regurgitation of blood may be seen on:

• echocardiogram (an ultrasound examination of the heart)
• transesophageal echocardiogram (TEE)
• cardiac color-Doppler study
• magnetic resonance imaging (MRI)
• cardiac catheterization

Hospitalization may be required for diagnosis and treatment of severe symptoms. Surgical repair or replacement of the valve is recommended if heart function is poor, if symptoms are severe, or if the condition deteriorates. Once the diagnosis of mitral regurgitation is made, periodic follow-up by a specialist is needed to determine the appropriateness of surgery.

Antibiotics are prescribed if bacterial infection is present, or prior to dental work or other procedures in cases of mitral valve prolapse. Anti-arrhythmic drugs (medications that regulate the heart rhythm) may be needed to control irregular rhythms and vasodilators (drugs that dilate blood vessels) to reduce the workload of the heart.

Digitalis may be used to strengthen the heartbeat, along with diuretics (water pills) to remove excess fluid in the lungs. Anticoagulant or antiplatelet medications (blood thinners) may be used to prevent clot formation if atrial fibrillation is present; atrial fibrillation increases the chances of clot formation. A low-sodium diet may be helpful.

Most individuals have no symptoms; but if a person develops symptoms, activity may be restricted.

• endocarditis (infection of the heart valve)
• heart failure
• pulmonary emboli (blood clots in the lungs)
• stroke
• clots to other areas
• arrhythmias (abnormal heart rhythms), including atrial fibrillation and lethal arrhythmias

Treat strep infections promptly to prevent rheumatic fever. Treat other causative disorders.

Note any history of heart valve disease or congenital heart disease before treatment by a health care provider or dentist. Any dental work, including cleaning, and any invasive procedure can introduce bacteria into the bloodstream. This bacteria can infect a damaged mitral valve, causing endocarditis. Preventive treatment with antibiotics given just before dental or other invasive procedures may decrease the risk of endocarditis.