PATHOLOGY OF MITRAL-VALVE-STENOSIS AND PURE MITRAL REGURGITATION .1.

This two-part article examines the histologic and morphologic basis fo r stenotic and purely regurgitant mitral valves. In Part I, conditions producing mitral valve stenosis are reviewed. In over 99% of stenotic mitral valves, the etiology is rheumatic disease. Other rare causes o f mitral stenosis include congenitally malformed valves, active infect ive endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgitat ion will be discussed. In contrast to the few causes of mitral stenosi s, the causes of pure (no element of stenosis) mitral regurgitation ar e multiple. Some of the conditions producing pure regurgitation includ e floppy mitral valves, infective endocarditis, papillary muscle dysfu nction, rheumatic disease, and ruptured chordae tendineae.