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Overview of Heart Valve Disorders
Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles—see see ). Each ventricle has a one-way "in" (inlet) valve and a one-way "out" (outlet) valve. In the right ventricle, the inlet valve is the tricuspid valve, which opens from the right atrium, and the outlet valve is the pulmonary (pulmonic) valve, which opens into the pulmonary artery. In the left ventricle, the inlet valve is the mitral valve, which opens from the left atrium, and the outlet valve is the aortic valve, which opens into the aorta. Each valve consists of flaps (cusps or leaflets) that open and close like one-way swinging doors.
The heart valves can malfunction either by leaking (termed regurgitation) or by not opening adequately and thus partially blocking the flow of blood through the valve (termed stenosis). Either problem can greatly interfere with the heart's ability to pump blood. Sometimes a valve has both problems.
Faulty valves generally create murmurs and other abnormal heart sounds that a doctor can hear with a stethoscope. Faulty valves can be identified by using echocardiography. Often, minor degrees of regurgitation are not detected with a stethoscope but are detected during echocardiography. Doctors often regard this as a normal finding.
A faulty valve may be repaired or replaced. Repair may require surgery but may sometimes be accomplished during heart catheterization (see Cardiac Catheterization and Coronary Angiography), particularly when the problem is a valve with stenosis. A stenotic valve can sometimes be stretched open using a procedure called balloon valvuloplasty. In this procedure, a balloon-tipped catheter is threaded through a vein and eventually into the heart. Once inside the faulty valve, the balloon is inflated, separating the valve cusps. This procedure does not require a general anesthetic and allows a quick recovery.
Understanding Stenosis and Regurgitation
Two types of valves are available for replacement, a mechanical type and one made from the heart valve of a pig or cow (bioprosthetic). Mechanical valves last for many years, but people with mechanical valves must take anticoagulants for the rest of their lives to prevent blood clots from forming in the valve. Bioprosthetic valves generally deteriorate and require replacement after 10 to 12 years but do not require use of anticoagulants for more than a few months after surgery. Some newer bioprosthetic valves are more durable and may not require replacement.
Replacing a Heart Valve
Abnormal valves and all replacement valves can become infected. People with replacement valves need to take prophylactic antibiotics, which are antibiotics taken at certain times (for example, before some dental or medical procedures) in order to prevent bacterial infection of the valves (infective endocarditis—see Infective Endocarditis).
As people age, the mitral and aortic valves thicken. The aorta becomes stiffer, which increases blood pressure and stress on the mitral valve, and the heart requires additional oxygen to pump blood effectively. These age-related changes may lead to symptoms and complications in older people with heart disease.
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