Although mitral valve prolapse is usually a lifelong disorder, many people with this condition never have symptoms. When diagnosed, people may be surprised to learn that they have a heart condition.

When signs and symptoms do occur, it may be because blood is leaking backward through the valve (regurgitation). Mitral valve prolapse symptoms can vary widely from one person to another. They tend to be mild and develop gradually. Symptoms may include:

• A racing or irregular heartbeat (arrhythmia)
• Dizziness or lightheadedness
• Difficulty breathing or shortness of breath, often when lying flat or during physical activity
• Fatigue
• Chest pain that's not caused by a heart attack or coronary artery disease

When your heart is working properly, the mitral valve closes completely during contraction of the left ventricle and prevents blood from flowing back into your heart's upper left chamber (left atrium).

But in some people with mitral valve prolapse, one or both of the mitral valve's flaps (leaflets) have extra tissue bulging (prolapsing) like a parachute into the left atrium each time the heart contracts.

The bulging may keep the valve from closing tightly. When blood leaks backward through the valve, it's called mitral valve regurgitation.

This may not cause problems if only a small amount of blood leaks back into the atrium. More-severe mitral valve regurgitation can cause symptoms such as shortness of breath, fatigue or lightheadedness.

Another name for mitral valve prolapse is click-murmur syndrome. When a doctor listens to your heart using a stethoscope, he or she may hear a clicking sound as the valve's leaflets billow out, followed by a murmur resulting from blood flowing back into the atrium. Other names to describe mitral valve prolapse include:

• Barlow's syndrome
• Floppy valve syndrome
• Billowing mitral valve syndrome
• Myxomatous mitral valve disease

Mitral valve prolapse can develop in any person at any age.

Serious symptoms of mitral valve prolapse tend to occur most often in men older than 50.

Mitral valve prolapse can run in families and may be linked to several other conditions, such as:

• Marfan syndrome
• Ehlers-Danlos syndrome
• Ebstein's anomaly
• Muscular dystrophy
• Graves' disease
• Scoliosis

Although most people with mitral valve prolapse never have problems, complications can occur. They may include:

• Mitral valve regurgitation. The most common complication is a condition in which the valve leaks blood back into the left atrium (mitral valve regurgitation).

Being male or having high blood pressure increases your risk of mitral valve regurgitation.

If regurgitation is severe, you may need surgery to repair or replace the valve in order to prevent heart failure.

• Heart rhythm problems (arrhythmias). Irregular heart rhythms most commonly occur in the upper chambers of the heart. They may be bothersome, but aren't usually life-threatening.

People with severe mitral valve regurgitation or severe deformity of their mitral valve are most at risk of having rhythm problems, which can affect blood flow through the heart.

• Heart valve infection (endocarditis). The inside of your heart is lined by a thin membrane called the endocardium. Endocarditis is an infection of this inner lining.

An abnormal mitral valve increases your chance of getting endocarditis from bacteria, which can further damage the mitral valve.

People at high risk of endocarditis may be prescribed antibiotics before certain dental and medical procedures, to reduce the risk of infection.