- A normal mitral valve opens wide to allow blood from the left atrium (upper chamber) to flow into the left ventricle (lower chamber) and closes tightly as blood is pumped out of the left ventricle.
- Mitral stenosis is a narrowing or obstruction of the mitral valve that prevents the valve from opening properly
- Mitral regurgitation means that the mitral valve does not close fully, allowing blood to regurgitate, or spill back, into the atrium when the left ventricle contracts. In mitral valve prolapse, the flaps of the mitral valve may protrude or billow back into the left atrium.
The heart has four valves, two on the right side of the heart, the tricuspid and pulmonary valves, and two valves on the left side of the heart, the mitral and aortic valves. Each valve is made up of flap-like segments or leaflets that open and close so that blood flows through the heart in only one direction. Located on the left side of the heart, the mitral valve is bicuspid, having two cusps or leaflets.
The mitral valve separates the left atrium and left ventricle. When the heart relaxes, the mitral valve opens and blood from the left atrium fills the left ventricle. During the heart’s contraction, the mitral valve closes, preventing blood from flowing back to the left atrium. A diseased mitral valve no longer opens or closes properly.
Common mitral valve problems include:
- Mitral stenosis is the narrowing or obstruction of the mitral valve, which prevents its opening properly and inhibits blood flow from the atrium to the ventricle. The residual blood can increase the pressure in the atrium, causing it to enlarge, which can lead to atrial arrhythmias, or disturbances in the heart’s normal rhythm or rate, and edema, or fluid buildup throughout the body.
- Mitral regurgitation occurs when the valve closes incompletely or improperly during the ventricular contraction, allowing blood to flow from the left ventricle back into the atrium. Mild regurgitation may not cause problems, but as regurgitation persists, the left atrium can enlarge because of increased blood volume. Serious regurgitation can cause the left ventricle to compensate for the blood that leaks into the atrium by enlarging. An enlarged heart can grow weak and begin to fail.
Mitral valve prolapse, also called the click-murmur syndrome, floppy valve syndrome, or Reid-Barlow’s syndrome, is when the valve do not close properly and bulges into the left upper chamber. With mitral valve prolapse, the blood could leak back to the atrium. Although infrequently serious or symptomatic, it can be associated with serious mitral regurgitation.