Mitral Stenosis

Narrowing of the mitral valve

Mitral stenosis is a disorder in which the mitral valve does not fully open. This restricts blood flow.

Causes of Mitral Stenosis

Blood that flows between different chambers of the heart must flow through a valve. The valve between the two chambers on the left side of your heart is called the mitral valve. It opens up enough so that blood can flow from the upper chamber of the heart (left atrium) to the lower chamber (left ventricle). It then closes, keeping blood from flowing backwards.  

Mitral stenosis means that the valve cannot open enough. As a result, less blood flows to the body. The upper heart chamber swells as pressure builds up. Blood and fluid may then collect in the lung tissue (pulmonary edema), making it hard to breathe.  

In adults, mitral stenosis occurs most often in people who have had rheumatic fever. This is a disease that can develop after an illness with strep throat that was not properly treated. The valve problems develop five to ten years or more after having rheumatic fever.

Symptoms may not show up for even longer. Rheumatic fever is becoming rare in the United States because strep infections are most often treated. This has made mitral stenosis less common.

Rarely, other factors can cause mitral stenosis in adults. These include: 

  • Calcium deposits forming around the mitral valve
  • Radiation treatment to the chest
  • Some medications

Children may be born with congenital mitral stenosis or other birth defects involving the heart that cause mitral stenosis. Often, there are other heart defects present along with the mitral stenosis. Mitral stenosis may run in families.

Symptoms of Mitral Stenosis

Adults may have not symptoms. However, symptoms may appear or get worse with exercise or other activity that raises the heart rate. Symptoms will most often develop between ages 20 and 50.

Symptoms may begin with an episode of atrial fibrillation (especially if it causes a fast heart rate). Symptoms may also 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:

  • Feeling of pounding heart beat (palpitations)
  • Waking up due to breathing problems (this is the most common symptom)
  • Difficulty breathing during or after exercise, or when lying flat
  • Chest discomfort that increases with activity and extends to the arm, neck, jaw or other areas (this is rare)
  • Cough, possibly with bloody phlegm
  • Fatigue
  • Frequent respiratory infections, such as bronchitis
  • Swelling of feet or ankles

Your doctor may hear a murmur, or snap, or other abnormal heart sound when they listen to your heart and lungs. The typical murmur is a rumbling sound that is heard over the heart during the resting phase of the heart beat. The sound often gets louder just before the heart begins to contract. The exam may also reveal an irregular heart beat or lung congestion. Blood pressure is often normal.

Narrowing of blockage of the valve, or swelling of the upper heart chambers, may be seen on:

  • Chest X-Ray
  • CT scan of the heart
  • Echocardiogram
  • ECG (electrocardiogram)
  • MRI of the heart
  • Transesophageal echocardiogram (TEE)