Glycogen Aggregates in Cardiac Muscle Cell: A Cytopathological Study on Endomyocardial Biopsies

Glycogen aggregates in the cardiac muscle cell, which have been frequently demonstrated in endomyocardial biopsies under the transmission electron microscope, were studied using the optical microscope in order to clarify their histopathological significance in various heart diseases. The right ventricular muscle biopsies were obtained from the following 120 patients: 24 cases of congestive cardiomyopathy, 26 of hypertrophic cardiomyopathy, 28 of atrial septal defect, 6 of primary pulmonary hypertension, 31 of bradyarrhythmic hearts and 5 controls. The tissue specimens were fixed with glutaraldehyde and osmium tetraoxide, and embedded in epoxy resin. Semi-thin sections from these specimens were dyed with tribasic staining originated by KUROTAKI (1972).Under the optical microscope, glycogen is clearly identified by its forming red stained areas which are seen not only in the subsarcolemmal layers and the perinuclear region, but also in the intermyofibrillar zones. The glycogen aggregates are more frequently observed in the specimens from the atrial septal defects and the bradyarrhythmic hearts than in the other cases.Thus, observation of glycogen aggregates reveals notable differences in appearance depending on the kinds of diseases. In the bradyarrhythmic hearts, the glycogen aggregates can be more readily observed in specimens from younger patients than in elderly ones. Furthermore, the glycogen aggregates appear regardless of both the grades of hypertrophy and degeneration in myocardial cells. These results do not agree with previous reports that the occurrence of glycogen is proportional with the grade of cardiac cell hypertrophy and/or damage.