[Ultrastructure of the heart conduction system in diphtheria]

Cytoarchitectonics and ultrastructure of the node and conducting myocardiocytes of the conducting system of the heart and surrounding blood capillaries and nervous fibers are described. In diphtheria, metabolic and destructive changes were found in the node myocytes, conducting myocardiocytes and surrounding structures. The most noticeable changes were seen in the left pedicle of the atrioventricular fascicle and later others components of the conducting heart system. These changes are more pronounced in clear cells of conducting myocardiocytes as compared to the node myocytes.