General
Mitral Stenosis is obstruction of the inflow of the left ventricle by an abnormally narrowed mitral valve. Nearly always rheumatic in origin, MS is not as common in developed countries as earlier. However, with a latency period (between the initial infection and the symptomatic valvular dysfunction),  not uncommonly up to more than 20 years, MS is still found in the elderly.  In developing countries it is still a common illness and is in many countries the leading cause of congestive heart failure.  Although rare, congenital mitral stenosis and left atrial myxomia are other causes.