By Craig M. Walker, M.D.
Medical Director,
Cardiocascular Institute of the South

The heart is a four-chambered pump which controls blood flow through a remarkable series of valves, which open and close at just the right moment in each cycle of the heartbeat. For most of us, these valves function flawlessly for our entire lives.

In the small percentage of the population that does experience heart valve problems, by far the most common is mitral valve prolapse, a condition more frequently encountered in women than men. Studies have shown that the condition affects at least six percent of women.

The mitral valve controls blood flow between the left upper and lower chambers of the heart. The upper chamber -- the left atrium -- receives freshly oxygenated blood from the lungs and delivers it, through the mitral valve, to the left ventricle -- the heart's main pumping chamber. The contraction of the left ventricle sends fresh blood coursing through the arterial system to provide oxygen and nutrients to the entire body.

The mitral valve has two flaps, attached by strings of connective tissue to muscles in the ventricle beneath it. The valve remains open when the ventricle is relaxed. As the ventricle begins to contract, the valve snaps shut, blocking backflow of blood into the atrium. As it closes, the muscles controlling it contract, preventing the flaps from swinging open in the other direction from the building pressure in the ventricle.

In mitral valve prolapse, one or both of the valves are enlarged, and the strings of connective tissue are too long or too stretchy, permitting the valve to be pushed upward into the atrium during the contraction of the ventricle. In more severe cases, the improperly closed valve permits some blood to leak backward into the atrium -- a condition called mitral valve regurgitation..

Generally, however, mitral valve prolapse is not serious enough to cause much of a problem. The average MVP patient has no symptoms at all, and only learns of the condition when a physician, listening to his or her heartbeat with a stethoscope, detects the characteristic clicking of the valve's improper closure.

To confirm and assess the extent of mitral valve prolapse, an echocardiogram -- creating an image of the beating heart with high-frequency sound waves -- may be called for.

If the condition does produce symptoms, they most often take the form of heart palpitations -- "skipped beats"-- or other heart rhythm irregularities. Usually these irregularities are more annoying than significant. In a still smaller percentage of patients, there may be chest pain, shortness of breath or a tendency to tire readily.

Usually, no treatment is required at all, though some patients with MVP may need to take antibiotics before undergoing dental treatment or surgery, in order to reduce the risk of infection of the valve. In the most extreme cases, the valve must be replaced surgically.

Mitral valve prolapse is generally not associated with any other heart disease, and no one knows why it occurs. Fortunately, it's one of those conditions for which the heart generally has the reserve power to compensate without harm.

&copy 1995 Cardiocascular Institute of the South

For further information, call Jane Arnette, Cardiocascular Institute of the South/Houma, 1-800-425-2565, or Jim Keyser at 1-800-848-2715. E-mail questions or comments to: jakeyser@cardio.com.

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