HEART VALVE MALFUNCTION
Malfunction of one of the four valves within the heart can cause problems that affect the entire circulatory system. A leaky valve does not close all the way, allowing some blood to flow backward as the heart contracts. This backward flow decreases the amount of oxygen the heart can deliver to the tissues with each beat. A stenotic valve, which is stiff and does not open fully, requires the heart to pump with increased force to propel blood through the narrowed opening. Over time, either of these problems can lead to damage of the overworked heart muscle.

Some people are born with malformed valves. Such congenital malformations may require treatment soon after birth, or they may not cause problems until a person reaches adulthood. A heart valve may also become damaged during life, due to infection, connective tissue disorders such as Marfan syndrome, hypertension, heart attack, or simply aging.

A well-known, but poorly understood, type of valve malfunction is mitral valve prolapse. In this condition, the leaflets of the mitral valve fail to close properly and bulge backward like a parachute into the left atrium. Mitral valve prolapse is the most common type of valve abnormality, affecting 5 to 10 percent of the United States population, the majority of them women. In most cases, mitral valve prolapse does not cause any problems, but in a few cases the valve’s failure to close properly allows blood to leak backwards through the valve.

Another common cause of valve damage is rheumatic fever, a complication that sometimes develops after an infection with common bacteria known as streptococci. Most common in children, the illness is characterized by inflammation and pain in the joints. Connective tissue elsewhere in the body, including in the heart, heart valves, and pericardium, may also become inflamed. This inflammation can result in damage to the heart, most commonly one of the heart valves, that remains after the other symptoms of rheumatic fever have gone away.

Valve abnormalities are often detected by listening to the heart with a stethoscope. Abnormal valves cause extra sounds in addition to the normal sequence of two heart sounds during each heartbeat. These extra heart sounds are often known as heart murmurs, and not all of them are dangerous. In some cases, a test called echocardiography may be necessary to evaluate an abnormal valve. This test uses ultrasound waves to produce images of the inside of the heart, enabling doctors to see the shape and movement of the valves as the heart pumps.

Damaged or malformed valves can sometimes be surgically repaired. More severe valve damage may require replacement with a prosthetic valve. Some prosthetic valves are made from pig or cow valve tissue, while others are mechanical valves made from silicone and other synthetic materials.