Mitral Valve Replacement

Mitral valve repair is an open heart procedure performed by cardiothoracic surgeons to treat stenosis (narrowing) or regurgitation (leakage) of the mitral valve. The mitral valve is the "inflow valve" for the left side of the heart. Blood flows from the lungs, where it picks up oxygen, and into the left atrium. When it opens, the mitral valve allows blood to flow from the left atrium to the heart's main pumping chamber called the left ventricle. It then closes to keep blood from leaking back into the lungs when the ventricle contracts (squeezes) to push blood out to the body. It has two flaps, or leaflets.

The mitral valve is highlighted on this illustration of a heart. The mitral valve is the "inflow valve" for the left side of the heart. Blood flows from the lungs, where it picks up oxygen, and into the left atrium. When it opens, the mitral valve allows blood to flow from the left atrium to the heart's main pumping chamber called the left ventricle.

Surgery may be necessary when the valve opens or closes incompletely. A stenotic (narrow) valve does not let the blood easily into the heart causing blood to "back up" and pressure to build up in the lungs. This makes it difficult for the heart to increase the amount of blood that it pumps with exercise, and may produce symptoms of shortness of breath - especially with activity. If the leaflets do not meet correctly for any reason (and many things may cause this), blood may leak backward into the lungs each time the heart pumps. Since some of the blood leaks backwards, the heart has to pump more blood with each contraction in order to push the same amount of blood forward. This is called volume overload. The heart can compensate for this overload for many months or years, provided that the leakage came on slowly and progressively. Eventually, the heart begins to fail and patients show symptoms of shortness of breath or fatigue (tiredness).

When it opens (left), the mitral valve allows blood to flow into the heart's main pumping chamber called the left ventricle. It then closes (right) to keep blood from leaking back into the lungs when the ventricle contracts (squeezes) to push blood out to the body. It has two flaps, or leaflets.

What Causes Mitral Valve Problems?

Mitral valve problems are rarely caused by a birth defect, otherwise known as a congenital condition. More often, simple "wear and tear" may cause part of the valve mechanism to fail. This is called "degenerative disease". This may be related to advancing age, although many young people will have this condition as well. Rheumatic fever may damage the mitral valve causing stenosis or regurgitation. Occasionally the mitral valve is damaged by infection or bacterial endocarditis. Ischemic heart disease (coronary artery disease) can also cause the mitral valve to leak.