Health Encyclopedia

Mitral stenosis

Definition

Mitral stenosis is a heart valve disorder that involves 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.

Alternative Names

Mitral valve obstruction

Causes, incidence, and risk factors

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

In adults, mitral stenosis most commonly occurs in people who have had rheumatic fever. Since rheumatic fever rates are declining in the United States, the rate of mitral stenosis is also decreasing. Only rarely do other disorders cause mitral stenosis in adults.

In children, congenital mitral stenosis is more often part of a group of heart deformities.

In children, mitral stenosis may run in families.

Symptoms

There are often no symptoms in adults. However, symptoms may appear or get worse with exercise or any activity that raises the heart rate. In adults, symptoms usually develop between the ages of 20 and 50.

In infants and children, symptoms may be present from birth (congenital).

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 or lungs, or other heart disorders.

Symptoms may include:

Chest discomfort (rare)
- Tight, crushing, pressure, squeezing, constricting
- Radiates to the arm, neck, jaw, or other areas
- Increases with activity, decreases with rest
Cough, possibly bloody
Difficulty breathing during or after exercise or when lying flat; may wake up with difficulty breathing
Fatigue, tired easily
Frequent respiratory infections such as bronchitis
Poor growth in children
Sensation of feeling the heart beat (palpitations)
Swelling of feet or ankles

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 sound that is heard over the heart during the resting phase of the heartbeat. 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.

In adults, mitral stenosis may be difficult to distinguish from left atrial myxoma (a tumor of the heart).

Narrowing or obstruction of the valve or swelling of the upper heart chambers may show on:

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

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. Anticoagulants (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.

Complications

Atrial fibrillation
Emboli (migration of clot) to the intestines, kidneys, or other areas
Pulmonary edema
Pulmonary hypertension
Right-sided heart failure
Stroke

Calling your health care provider

Call your health care provider if you have symptoms of mitral stenosis.

Call your health care provider if you have mitral stenosis and symptoms do not improve with treatment, or if new symptoms appear.

Prevention

Follow treatment recommended for conditions that may cause valve disease. Treat strep infections promptly to prevent rheumatic fever. Tell your health care provider if you have a family history of congenital heart diseases.

Mitral stenosis itself often cannot be prevented, but complications can be prevented. Inform your health care provider of any history of heart valve disease before medical treatment.

For example, any dental work, including cleaning, and any invasive procedure, can introduce bacteria into the bloodstream. These bacteria can infect a damaged mitral valve. Preventive antibiotics before these procedures will help to decrease the risk for endocarditis.

Taking anticoagulation medication as prescribed is very important because mitral stenosis tends to produce both cerebral and peripheral emboli (blood clots in the brain and extremities), which can cause severely disabling and/or life-threatening complications like stroke.

References

Otto CM, Bonow RO. Valvular heart disease. In: Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007: chap 62.

Karchmer AW. Infective Endocarditis. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo: WB Saunders; 2007: chap. 63.

Review Date:5/12/2008
Reviewed By:Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School, and Private practice specializing in Cardiovascular Disease, Watertown, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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