heart and blood vessel disorders
Mitral Stenosis
Introduction
Mitral stenosis is a narrowing of the mitral valve opening that blocks (obstructs) blood flow from the left atrium to the left ventricle. Mitral stenosis usually results from rheumatic fever, but infants can be born with the condition. Mitral stenosis does not cause symptoms unless it is severe. Doctors make the diagnosis after hearing a characteristic heart murmur through a stethoscope placed over the heart, and they use echocardiography to make a more detailed diagnosis. Treatment begins with use of diuretics and beta-blockers or calcium channel blockers. The valve can be stretched open with a catheter, but occasionally the valve needs to be replaced, requiring open-heart surgery. (See also Overview of Heart Valve Disorders and the video The mitral valve is in the opening between the left atrium and the left ventricle. The mitral valve opens to allow blood from the left atrium to fill the left ventricle and closes as the left ventricle contracts to prevent blood from flowing back into the left atrium as the ventricle pumps blood into the aorta. If a disorder causes the valve flaps to become thick and stiff, the valve opening is narrowed. Sometimes the stiffened valve also fails to close completely, and Mitral Regurgitation develops. In mitral stenosis, blood flow through the narrowed valve opening is reduced. As a result, the volume and pressure of blood in the left atrium increases, and the left atrium enlarges. The enlarged left atrium often beats rapidly in an irregular pattern (a disorder called Atrial Fibrillation and Atrial Flutter ). As a result, the heart's pumping efficiency is reduced because the fibrillating atrium is quivering rather than pumping. Consequently, blood does not flow through the atrium briskly, and blood clots may form inside the chamber. If a clot breaks loose (becoming an embolus), it is pumped out of the heart and may block an artery, possibly causing a If mitral stenosis is severe, pressure increases in the blood vessels of the lungs (pulmonary hypertension) , resulting in Heart Failure (HF) with fluid accumulation in the lungs and a low level of oxygen in the blood. If a woman with severe mitral stenosis becomes pregnant, heart failure may develop rapidly. 