Mitral valve prolapse, which is also called MVP, is a condition in which the mitral valve balloons back into the left atrium when the heart pumps. The mitral valve separates the heart's left atrium, or upper chamber, from the left ventricle, or lower chamber.

What is going on in the body?

The left atrium receives blood from the lungs and passes it through the mitral valve to the left ventricle. The left ventricle pumps blood to the rest of the body. The mitral valve normally remains firm when the left ventricle contracts.

For reasons that are not clear, the tissues that make up the valve sometimes thicken and weaken. When that occurs, the valve balloons back into the left atrium when the left ventricle pumps. This sometimes allows blood to leak backward, a condition known as chronic mitral regurgitation.

Mitral valve prolapse is generally not serious. In older men, the cords around the mitral valve can sometimes rupture for no known reason. This rupture causes more severe leakage.

What are the causes and risks of the condition?

The cause of mitral valve prolapse is unknown. It is more common in people with low body weight and low blood pressure. It is also more common in those who have a hollow at the lower part of the breastbone, called pectus excavatum or funnel chest.

About 3% to 5% of the population are diagnosed with mitral valve prolapse. On autopsy, MVP is identified in 7% of the population. Mitral valve prolapse is rare before puberty and usually develops at 10 to 16 years of age. Women have MVP three times more often than men.

Mitral valve prolapse occurs more commonly in individuals with certain diseases and conditions, including the following: