Mitral Valve Prolapse

What Is It?

Mitral valve prolapse, also known as Barlow's syndrome or systolic click-murmur syndrome, is a malfunction of the heart's mitral valve, the physical doorway between the heart's left atrium and left ventricle. Normally, the mitral valve closes when the ventricle's muscles contract, preventing a blood from flowing back into the left atrium when the heart pumps blood to the rest of the body. In mitral valve prolapse, however, a slight deformity of the mitral valve prevents the valve from closing normally. This appears as an abnormal floppiness or "prolapse" of the valve. The result is that small amounts of blood leak back into the left atrium, with very little effect on the heart's overall ability to pump blood.

In some people, the leakage progresses to mitral regurgitation, a significant backflow of blood into the left atrium. People with severe mitral regurgitation can develop symptoms such as shortness of breath, fatigue and leg swelling. Rarely, heart surgery is needed to repair these damaged valves.

In most people with mitral valve prolapse, the cause is unknown. However, in a small number of patients, mitral valve prolapse may be related to another medical condition, such as an inherited abnormality in the way the body produces collagen (connective tissue), or rheumatic heart disease (a rare complication of strep throat).

Health experts estimate that mitral valve prolapse currently affects up to 5 percent of people in the United States. For unknown reasons, the condition is most common in women between 14 to 30. Although the condition sometimes affects several members of the same family, no specific genetic (inherited) basis has been identified for the problem.

Symptoms

Most people with mitral valve prolapse do not have any symptoms, and the condition is discovered only when a doctor hears a specific type of heart murmur during a routine physical examination. Some people may develop palpitations, a racing pulse, fainting or a feeling of lightheadedness. There also may be prolonged chest pain, usually located under the breastbone, which, unlike angina (the chest pain of coronary artery disease), is not necessarily related to stress or exercise. In the people with mitral regurgitation (about 15 percent of patients with mitral valve prolapse for 15 years), there may be symptoms of congestive heart failure (fatigue, shortness of breath, leg swelling).

Diagnosis

Your doctor will review your medical history, including any history of heart disease, and will ask questions about symptoms such as anxiety, palpitations, light-headedness, fainting and chest pain. He or she also will ask about your family's history of heart disease.

You and your doctor may not suspect that you have mitral valve prolapse until your doctor hears a sound called a systolic click with the stethoscope during the cardiac portion of a routine physical examination. The systolic click is an abnormal heart sound related to the malfunction of the mitral valve in mitral valve prolapse. In some patients, an additional heart murmur (an abnormal heart sound produced by turbulent blood flow) also can be heard.