Mitral valve prolapse

Alternative names

Barlow's syndrome; Floppy mitral valve; Myxomatous mitral valve; Billowing mitral valve; Systolic click-murmur syndrome; Prolapsing mitral leaflet syndrome

Definition

Mitral valve prolapse is a disorder in which the heart's mitral valve - which separates the left upper chamber (atrium) from the left lower chamber (ventricle) - billows out and does not close properly.

Causes, incidence, and risk factors

Mitral valve prolapse can be caused by a variety of mechanisms. In most cases, it is harmless and does not cause symptoms or need to be treated. In a small number of cases, it can cause severe mitral regurgitation (leakage of blood back through the valve) and needs to be treated with surgery.

Some forms of mitral valve prolapse seem to be hereditary. Mitral valve prolapse has been associated with Marfan's syndrome (a disorder present from birth), Graves' disease, and other disorders.

Many people with mitral valve prolapse are thin women who may have minor chest wall deformities, scoliosis, or other disorders. There may also be an atrial septal defect (a hole in the wall that separates the left and right upper heart chambers) high in the wall of the heart (called an ostium secundum defect).

Symptoms

• sensation of feeling the heart beat (palpitations)
  
• chest pain (unrelated to coronary artery disease or a heart attack)
  
• difficulty breathing after exertion
  
• fatigue
  
• cough
  
• shortness of breath when lying flat (orthopnea)
  

Note: In some cases, there may be no symptoms or there may be a gradual onset of symptoms.

Signs and tests

The doctor may feel a thrill (vibration) over the heart. Using a stethoscope, the doctor may hear a distinctive murmur or other abnormal sounds. (The murmur is described as a mid-systolic click and is sometimes followed by a late systolic murmur. This means a click sound is heard midway in the "beating" part of the heartbeat cycle, followed by a murmur near the end of this time.) The murmur is worse when standing. Blood pressure is usually normal.

Mitral valve prolapse and associated regurgitation may show on:

• Echocardiogram (an ultrasound examination of the heart)
  
• Color-flow Doppler examination
  
• Cardiac catheterization
  
• Chest X-rays (will show fluid in the lungs or an enlarged left atrium if severe mitral regurgitation is present)