Definition
Mitral stenosis is a narrowing or obstruction of the opening of the mitral valve, which separates the upper and lower chambers on the left side of the heart. This prevents adequate blood flow between the left atrium (upper chamber) and ventricle (lower chamber).
Alternative Names
Mitral valve obstruction
Causes
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 obstructs the blood flow from the left atrium to the left ventricle. This narrowing can reduce the amount of blood that flows forward to the body. The atrium enlarges 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, or symptoms may appear or worsen with exercise or increase in heart rate.
Exams and Tests
A stethoscope examination reveals a distinctive murmur, snap, or other abnormal heart sound. The typical murmur is described as a "rumbling apical diastolic murmur with pre-systolic accentuation." This means a rumbling sound is heard over the point of the heart during the resting phase of the heart beat, and it gets more pronounced just before the heart contraction begins.
Examination may also reveal
irregular heartbeat or lung congestion.
Blood pressure is usually normal. There may be vibration (thrill), or a tapping sensation may be noted on palpation over the heart. 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), also often shows atrial fibrillation
- Cardiac catheterization
This disease may also alter the results of the following tests:
Treatment
No treatment may be necessary if symptoms are absent or mild. Hospitalization may be required for diagnosis and for treatment of severe symptoms.
Medications include diuretics (water pills), nitrates, or beta-blockers. Digoxin may be used to treat atrial fibrillation. Blood thinners are used to prevent blood clots from forming and traveling to other parts of the body. Heart valve surgery to repair or replace the valve is usually necessary if there are serious symptoms.
Balloon valvuloplasty may be considered instead of surgery. This procedure entails placing a balloon into the mitral valve through a catheter that is inserted into a leg vein. The balloon is then inflated, widening the mitral valve and improving blood flow.
Outlook (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.
Possible Complications
- Pulmonary edema
- Atrial fibrillation
- Pulmonary hypertension
- Right-sided heart failure
- Stroke
- Emboli (migration of clot) to the intestines, kidneys, or other areas
When to Contact a Medical Professional
Call your health care provider if symptoms suggest 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.
