PATHOLOGY OF MITRAL-VALVE-STENOSIS AND PURE MITRAL REGURGITATION .2.

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 were reviewed. In over 99% of stenoti c mitral valves. the etiology is rheumatic disease. Other rare causes of mitral stenosis include congenitally malformed valves, active infec tive endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgita tion are discussed. In contrast to the few causes of mitral stenosis, the causes of pure (no element of stenosis) mitral regurgitation are m ultiple. Some of the conditions producing pure regurgitation include f loppy mitral valves, infective endocarditis, papillary muscle dysfunct ion. rheumatic disease, and ruptured chordae tendineae.