Mitral stenosis Health Article

Definition

Mitral stenosis is a narrowing or blockage of the opening of the mitral valve, which separates the upper and lower chambers on the left side of the heart. This prevents proper blood flow from moving between the left atrium (upper chamber of the heart) and ventricle (lower chamber of the heart).

Alternative Names

Mitral valve obstruction

Causes, incidence, and risk factors

Mitral stenosis is a heart valve disorder. Symptoms usually develop between the ages of 20 and 50. It most commonly occurs in people who have had rheumatic fever. Since rheumatic fever rates are declining in the United States, the incidence of mitral stenosis is also decreasing. Only rarely do other disorders cause mitral stenosis.

The condition may be present from birth (congenital), but it seldom occurs as a single defect. Congenital mitral stenosis is more often part of a complex heart deformity.

Mitral stenosis prevents the valve from opening properly and blocks the blood flow from the left atrium to the left ventricle. As the valve area becomes smaller, less blood flows forward to the body. The atrium swells as pressure builds up and blood may flow back into the lungs, resulting in pulmonary edema (fluid in the lung tissue).

The main risk factor for mitral stenosis is a history of rheumatic fever. Symptoms may begin with an episode of atrial fibrillation or may be triggered by pregnancy or other stress on the body such as infection (in the heart, lungs, etc.) or other cardiac disorders.

Symptoms

• Difficulty breathing
  • During or after exercise
  • When lying flat (orthopnea)
  • Awakening at night with difficulty breathing
• Cough
  • May have blood in the sputum (hemoptysis)
• Fatigue, tired easily
• Frequent respiratory infections (such as bronchitis)
• Chest discomfort (rare)
  • Tight, crushing, pressure, squeezing, constricting
  • Radiates to the arm, neck, jaw, or other areas
  • Increases with activity, decreases with rest
• Sensation of feeling the heart beat (palpitations)
• Swelling of feet or ankles

Note: There are often no symptoms. However, symptoms may appear or get worse with exercise or any activity that raises the heart rate.

Signs and tests

The health care provider will listen to the heart and lungs with a stethoscope. A distinctive murmur, snap, or other abnormal heart sound may be heard. The typical murmur is a "rumbling apical diastolic murmur with pre-systolic accentuation." This means a rumbling sound is heard over the heart during the resting phase of the heart beat. The sound gets louder just before the heart begins to contract.

The exam may also reveal an irregular heartbeat or lung congestion. Blood pressure is usually normal.

Mitral stenosis may be difficult to distinguish from left atrial myxoma (a tumor of the heart).

Narrowing or obstruction of the valve or enlargement of the atrium may show on:

• Echocardiogram
• Transesophageal echocardiogram (TEE)
• Doppler ultrasound
• Chest x-ray
• ECG (electrocardiogram)
• Cardiac catheterization
• MRI

This disease may also alter the results of the following tests:

• Swan-Ganz (right heart catheterization)
• Nuclear ventriculography (MUGA or RNV)

Treatment

Treatment depends on the symptoms and condition of the heart and lungs. Persons with mild symptoms or none at all may not need treatment. Hospitalization may be required for diagnosis and for treatment of severe symptoms.

There are a number of different treatment options.

Medications include diuretics (water pills), nitrates, or beta-blockers. Digoxin may be used to treat atrial fibrillation. Anti-coagulants (blood thinners) are used to prevent blood clots from forming and traveling to other parts of the body.

Some patients may need heart surgery to repair or replace the valve. Replacement valves can be made from different materials, some of which may last for decades and others which can wear out and require replacement.

Percutaneous mitral balloon valvotomy (also called valvuloplasty) may be considered instead of surgery. During this procedure, a catheter (tube) is inserted into a vein, usually in the leg, and up into the heart. A balloon on the tip of the catheter is inflated, widening the mitral valve and improving blood flow. This procedure is less likely to work in patients with severely damaged mitral valves.

Expectations (prognosis)

The outcome varies. The disorder may be mild, without symptoms, or may be more severe and eventually disabling. Complications may be severe or life threatening. Mitral stenosis is usually controllable with treatment and improved with valvuloplasty or surgery.