Figure 2.
Structural Analysis
Compared to the leading edge of normal control mitral valves (A, B), hypertrophic cardiomyopathy residual leaflets (C, D) are structurally disorganized. Trichrome staining of normal valves reveals a dense laminar fibrosa layer (A). Trichrome staining of hypertrophic cardiomyopathy leaflets reveals attenuated fibrosa with loose, fragmented collagen bundles (C). Elastic staining of normal valves reveals a compact spongiosa layer with laminar elastic fibers (B). Elastic staining of hypertrophic cardiomyopathy leaflets reveals an expanded spongiosa layer with fragmented, disorganized fibers (D). Weigert Resorcin/Fuchsin, elastic fibers = black. Trichrome, collagen = blue. HCM = hypertrophic cardiomyopathy; SIT = superimposed collagenous tissue.