Definition

Acute mitral regurgitation is a disorder in which the heart's mitral valve suddenly does not close properly, causing blood to leak (back-flow) into the left atrium (upper heart chamber) when the left ventricle (lower heart chamber) contracts.

Alternative Names

Mitral insufficiency; Acute mitral regurgitation

Causes, incidence, and risk factors

Regurgitation (leaking from insufficient valve closure) is caused by diseases that weaken or damage the valve or its supporting structures. Inadequate closure of the mitral valve causes blood to flow back to the left atrium. The blood flow to the rest of the body is decreased as a result and the heart may pump harder to try to compensate.

Acute mitral regurgitation may be the result of dysfunction or injury to the valve following a heart attack or infective endocarditis (infection of the heart valve). These conditions may rupture the valve, the papillary muscle or chordae tendineae (the structures that anchor the valve cusps). A rupture of these structures results in the valve leaflet prolapsing or flailing (protruding) into the atrium, leaving an opening for the backflow of blood.

Risk factors include a recent individual history of the disorders mentioned above.

See also: Chronic mitral regurgitation.

Symptoms

• Rapid breathing
• Shortness of breath that increases when lying flat (orthopnea)
• Sensation of feeling the heart beat (palpitations)
• Chest pain -- unrelated to coronary artery disease or a heart attack
• Cough

Note: Symptoms may start suddenly.

Signs and tests

Palpation may show thrill (vibration) over the heart. A stethoscope may reveal a distinctive murmur in the heart. However, this murmur may be absent in some cases of acute mitral regurgitation. If fluid backs up into the lungs, there may be crackles heard in the lungs. An extra heart sound (S4 gallop) may also be heard.

Blood pressure is usually normal.

The following tests may be performed:

• Echocardiogram 
• Color flow Doppler exam
• Transesophageal echocardiogram (TEE)
• Cardiac catheterization 
• Chest x-ray - may also show fluid in the lungs or prominent pulmonary veins.
• Swan-Ganz (right heart catheterization)  - may show high left atrial pressure. 
• ECG - usually shows a normal sinus rhythm but may show arrhythmias 
• Chest MRI scan 
• Radionuclide scans
• CT scan of the chest

Treatment

Hospitalization may be required for diagnosis and treatment of severe symptoms. The goal of treatment is to control the symptoms. Emergency surgery may be necessary if acute regurgitation is severe, usually resulting from endocarditis (valve infection), heart attack, or ruptured cordae (one of the supporting structures of the mitral valve).

Antibiotics may be prescribed if there is a bacterial infection. Anti-arrhythmics (drugs that regulate the heart rhythm) may be needed to control irregular rhythms. Vasodilators (drugs that dilate the blood vessels) reduce the workload of the heart. Digitalis may be used to strengthen the heartbeat and diuretics (water pills) to remove excess fluid in the lungs.

Anticoagulants or antiplatelet medications (blood thinners) may be used to prevent clot formation if atrial fibrillation is present, because atrial fibrillation increases the chances of clot formation. However, this treatment is primarily used for chronic mitral regurgitation.

In emergency situations when blood pressure cannot be maintained, devices such as the intra-aortic balloon pump (IABP) reduce backflow by enhancing forward blood flow into the aorta.

Support Groups

Expectations (prognosis)

The outcome varies and depends on underlying conditions and the severity of the acute regurgitation. Milder forms of acute mitral regurgitation may become a chronic condition. Acute mitral regurgitation can rarely be controlled with medications; surgery is usually necessary to repair or replace the mitral valve (see valve replacement). Arrhythmias associated with acute mitral regurgitation can sometimes be fatal.

Complications

• Chronic mitral regurgitation
• Endocarditis (valve infection)
• Heart failure
• Pulmonary edema (fluid in the lungs)
• Stroke
• Blood clots in other parts of the body 
• Arrhythmias, including atrial fibrillation

Calling your health care provider

Call your health care provider if symptoms indicate mitral valve regurgitation, or if symptoms worsen or do not improve with treatment. Call your health care provider if during treatment, signs of infection occur: fever, chills, muscle aches, headache, or malaise (general ill feeling).

Prevention

Prompt treatment of causative disorders reduces the risk of mitral regurgitation. 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.

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