The term stenosis means an abnormal narrowing of an opening. Any of several heart valves can be involved.
Mitral valve stenosis refers to a condition in the heart in which one of the valve openings has become narrow and restricts the flow of blood from the upper left chamber (left atrium) to the lower left chamber (left ventricle).
In the heart, the valve that regulates the flow of blood between the left atrium and the left ventricle is called the mitral valve. If the mitral valve is abnormally narrow, due to disease or birth defect, blood flow from the atrium to the ventricle is restricted. This restricted flow leads to an increase in the pressure of blood in the left atrium. Over a period of time, this back pressure causes fluid to leak into the lungs. It can also lead to an abnormal heart rhythm (atrial fibrillation), which further decreases the efficiency of the pumping action of the heart.
Mitral valve stenosis is almost always caused by rheumatic fever . As a result of rheumatic fever, the leaflets that form the opening of the valve are partially fused together. Mitral valve stenosis can also be present at birth. Babies born with this problem usually require surgery if they are to survive. Sometimes, growths or tumors can block the mitral valve, mimicking mitral valve stenosis.
If the restriction is severe, the increased blood pressure can lead to heart failure . The first symptoms of heart failure, which are fatigue and shortness of breath , usually appear only during physical activity. As the condition gets worse, symptoms may also be felt even during rest. A person may also develop a deep red coloring in the cheeks.
Mitral valve stenosis is usually detected by a physician listening to heart sounds. Normal heart valves open silently to permit the flow of blood. A stenotic valve makes a snapping sound followed by a "rumbling" murmur. The condition can be confirmed with a chest x ray and an electrocardiogram, both of which will show an enlarged atrium. Echocardiography , which produces images of the heart's structure, is also helpful in making the diagnosis. If surgery is necessary, cardiac catheterization may be done to fully evaluate the heart before the operation.
Drug therapy may help to slow the heart rate, strengthen the heart beat, and control abnormal heart rhythm. Drugs such as beta blockers , calcium channel blockers , and digoxin may be prescribed. A drug that prevents abnormal blood clotting (anticoagulant) called warfarin (Coumadin) may be recommended. If drug therapy does not produce satisfactory results, valve repair or replacement may be necessary.