cardiovascular disorders
Mitral Stenosis
Introduction
Mitral stenosis is narrowing of the mitral orifice that impedes blood flow from the left atrium to the left ventricle. The usual cause is rheumatic fever. Common complications are pulmonary hypertension, atrial fibrillation, and thromboembolism. Symptoms are those of heart failure; signs include an opening snap and a diastolic murmur. Diagnosis is by physical examination and echocardiography. Prognosis is good. Medical treatment includes diuretics, beta-blockers or rate-limiting calcium channel blockers, and anticoagulants. Effective treatment for more severe disease consists of balloon commissurotomy, surgical commissurotomy, or valve replacement. (See also Overview of Cardiac Valvular Disorders .) In mitral stenosis, mitral valve leaflets become thickened and immobile and the mitral orifice becomes narrowed due to fusion of the commissures and the presence of shortened, thickened, and matted chordae tendineae. Themost common causeis Rheumatic Fever None However, many patients do not recall having had rheumatic fever. In regions with high prevalence of rheumatic fever, patients often present by age 30 years, usually with commissural fusion of pliable, noncalcified leaflets. In regions with low prevalence, patients typically present between ages 50 and 70 years and with calcified fibrotic leaflets with subvalvular involvement in addition to commissural fusion. An increasingly prevalent cause in older patients is mitral annular calcification with extension of calcification into the leaflets, causing them to stiffen and not open fully. Women comprise 80% of rheumatic fever and mitral annular calcification cases. Occasionally, mitral stenosis is congenital or occurs after radiation therapy. If the valve cannot close completely, Mitral Regurgitation (MR) may coexist with mitral stenosis. Patients with mitral stenosis due to rheumatic fever may also have lesions of the aortic or tricuspid valve or both. Left atrial (LA) size and pressure increase progressively to compensate for mitral stenosis; pulmonary venous and capillary pressures also increase and may cause secondary Symptoms and Signs , leading to right ventricular (RV) LA enlargement predisposes to Atrial Fibrillation (AFib), a risk factor for thromboembolism. The faster heart rate and loss of atrial contraction with onset of atrial fibrillation often lead to sudden worsening of symptoms. 