Electron microscopic study of the biopsied cardiac muscle in Duchenne muscular dystrophy

Cardiac muscular biopsies were performed on 4 patients with Duchenne muscular dystrophy (DMD). None of the patients had cardiac symptoms and all of them exhibited normal electro- and echocardiographic findings. Electron microscopic examination of cardiac muscles from 4 patients with DMD disclosed proliferation of the mitochondria, changes in the cristae, abnormalities of the Z-bands, dilatation of the sarcoplasmic reticulum, deposition of glycogen, and changes in the nuclei. The most striking finding in these patients was that the residual bodies were increased and were observed mainly in the perinuclear region. These ultrastructural features suggest that an extreme exhaustion had already been present in myocardial tissue of the patients prior to the onset of cardiac symptoms.