Heart valves can malfunction on one of two ways: They can fail to close completely, allowing blood to flow backward, or they can become damaged, limiting blood flow.

Mitral valve prolapse is a condition in which blood leaks backward through the mitral valve in the heart. This backflow of blood may result in a heart murmur.

Mitral valve prolapse (MVP) is an uncommon and usually harmless problem. MVP is an improper closing of a heart valve that may allow some leakage of blood back toward the heart when pumping.

Heart murmurs may be caused by a number of factors or diseases, including defective heart valves, fever, and pregnancy.