Figure 1.

Residual Leaflet Histology

MVs from a cadaveric control (A, B) and a patient with hypertrophic cardiomyopathy (C, D), oriented with the proximal edge on left and free edge on right. Control valves have laminar structure, with trichrome staining (A) revealing a well-organized collagenous fibrosa layer that decreases in thickness in the distal leaflet (right), and elastic staining reveals a thin spongiosa layer that expands in the distal leaflet (B). Hypertrophic cardiomyopathy valves have attenuated fibrosa (C), expanded spongiosa (D), and are disorganized throughout. They also have superimposed collagenous tissue present at their distal portions (C, D) and an overall trend toward decreased thickness compared with controls. Weigert Resorcin/Fuchsin, elastic fibers = black. Trichrome, collagen = blue. HCM = hypertrophic cardiomyopathy.