What is mitral valve prolapse?

The mitral valve sits in the left side of the heart between the left atrium and left ventricle and is composed of two leaflets: anterior and posterior. The mitral valve opens in diastole, when the heart is resting, and allows blood to fill the left ventricle, then closes in systole when the left ventricle contracts. The closed mitral valve prevents blood from flowing backwards into the left atrium. The blood is thus pumped out of the left ventricle through the aortic valve and on to the body.

In some people, the mitral valve closes in a slightly improper way. Instead of the two leaflets coming together seamlessly, the leaflets come together in an awkward fashion and flop, or prolapse, into the left atrium during the forceful ventricular contraction. The prolapse may involve one or both the leaflets. This prolapse of the mitral valve causes a "click" sound that can be heard through a stethoscope. If the leaflets prolapse severely, then the mitral valve will leak, or regurgitate, blood back into the left atrium during systole. In severe cases of mitral valve prolapse, the valve leaflets can also become thickened over time. Patients with severe mitral valve prolapse with significant regurgitation are usually instructed by their cardiologist to take prophylactic antibiotics before having dental work.

Mitral valve prolapse is more common in women than in men. Patients with mitral valve prolapse frequently have symptoms of chest pain, the reasons for which are not well known. Mitral valve prolapse is also associated with heart rhythm abnormalities that cause symptoms of palpitations. These rhythm abnormalities are usually benign.