Floppy mitral valve chordae tendineae: Histopathologic alterations

Pathologic studies of floppy or myxomatous mitral valves have focused primarily on changes in the valve cusps, with little attention given to the chordae tendineae. In a systematic study of the histopathology of floppy mitral valve chordae tendineae, 128 nonruptured chordae from 8 severely regurgitant floppy mitral valves were compared to 152 chordae from 10 normal control mitral valves and to 152 chordae from 8 control mitral valves with severe regurgitation due to ischemic heart disease. Collagen alterations were observed in 2% of normal mitral valve chordae and 3% of control regurgitant mitral valve chordae compared to 38% of floppy mitral valve chordae. Moderate or severe acid mucopolysaccharide accumulation was observed in 2% of normal mitral valve chordae and 3% of control regurgitant mitral valve chordae compared to 39% of floppy mitral valve chordae. Nonuniform histopathologic alterations, rare in normal and control regurgitant mitral valve chordae tendineae, were frequent in floppy mitral valve chordae tendineae (p<0.001). Histopathologic alterations provide the basis for abnormal physical properties previously demonstrated in floppy mitral valve chordae tendineae and may predispose to chordal elongation and rupture.