The sections show multiple fragments of normal endomyocardium.
There is no inflammation, no myofiber hypertrophy, no myofiber disarray, and no fatty or fibrous replacement of myocytes. Fibrous tissue comprises less than 5% of the biopsy.
Electron microscopy shows morphologically normal intercalated discs, with close opposition of the sarcolemma of adjacent fibres, and normal mitochondria, with rectilinear cristae. There are minimal small globules of glycogen, as seen in normal cardiac muscle.
A. Heart, myocardial biopsies x6 - no pathology