Electron microscopic and light microscopic investigation of endomyocardial biopsies in the transplanted heart.

Samples from 16 endomyocardial biopsies obtained from three patients, provided cyclosporine immunosuppression, at 3-6 years since heart transplantation were examined in light and electron microscopy. In light microscopy, the endomyocardial biopsies of the patients examined within that period were free of signs of acute rejection, practically within the normal range. In electron microscopy, intercalated discs, glycogen, mitochondria, myofibrils, lipid droplets, lipofuscin granules, sarcoplasmic reticulum in myocytes and interstitial space were examined. Results of ultrastructural studies indicate that alteration of myocytes increases with time, the longer the interval since heart transplantation, the more myocytes show changes in the above structures. Irreversible changes and myelin bodies were found sporadically in myocytes that were in normal state.