Heart Valve Disorders

The heart has four chambers—two small upper chambers (atria) and two larger lower chambers (ventricles). Each chamber is closed by a one-way valve. For various reasons these valves can malfunction, causing leakage (regurgitation) or failure to open properly (stenosis). The mitral valve, which allows blood to flow from the left atrium to the left ventricle (the main pumping chamber of the heart), and the aortic valve, which allows blood to flow from the left ventricle to the aorta (the main artery of the body), are the most common sites for valve disease. These valves are under great strain from the powerful contractions of the left ventricle, which pumps blood throughout most of the body.

Mitral Valve Prolapse

Mitral valve prolapse is the most common valve disorder. Usually it is an inherited structural defect. The two parts, or leaflets, of the mitral valve thicken, preventing them from coming together properly. The leaflets bulge back into the left atrium as the ventricle contracts, allowing small amounts of blood to leak back into the atrium. Prolapse is a term that means slippage out of position; in this case the valve leaflets have difficulty being in their correct position because they are too thick.

Most people with mitral valve prolapse experience no symptoms. Others may have a wide range of symptoms—such as chest pain, palpitations (an awareness of one's heartbeat), migraine headaches, dizziness, and fatigue—that cannot be explained by the valve problem alone.

Physicians diagnose mitral valve prolapse by using a stethoscope to listen to the characteristic clicking sound produced by the valves as they hit against one another. The condition also produces a heart murmur, or slight rushing sound, that the physician hears through the stethoscope when the heart contracts. Echocardiography (an ultrasound examination of the heart) allows a doctor to view the prolapse and determine its severity.

Most people with mitral valve prolapse do not need treatment. When symptoms such as extra heartbeats, a rapid heartbeat, or chest pain become bothersome, medications are prescribed to control them. In rare cases, when leakage becomes severe, surgical repair or valve replacement may be required. People with mitral valve prolapse are usually given antibiotics before dental or surgical procedures to decrease the risk that bloodborne bacteria will infect the heart valve.

Mitral Valve Regurgitation

Mitral valve regurgitation, also called mitral incompetence or mitral insufficiency, is leakage of blood back through the mitral valve into the left atrium each time the left ventricle contracts. This increases the volume and pressure in the

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