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).

Mitral stenosis is a heart valve disorder. In adults, symptoms usually develop between the ages of 20 and 50. In infants and children, symptoms may be present from birth (congenital).

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 incidence 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.

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).

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.

In children, mitral stenosis may run in families.

• 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
• Poor growth in children

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

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.

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 enlargement of the atrium may show on:

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

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

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