A MORPHOLOGIC STUDY ON HUMAN CONDUCTION SYSTEM OF HEART CONSIDERING INFLUENCES OF SOME DISORDERS OF INDIVIDUALS

The authors have investigated the aging changes of the human AV node, AV bundle, and bundle branches considering the influences of various disorders of individuals upon these conduction tissues. These conduction tissues began to develop gradually from the infant stage and the development was completed by young adult stage. Aging changes of the conduction tissues were fat infiltration, fibrosis and elastosis, disappearance of muscle fiber, and general atrophy of the conduction tissues. They were thought to occur not only by aging but also by the influences of various disorders particularly of longstanding chronic diseases. Changes of the conduction tissues seem to be related with thickening and luminal narrowing of the AV nodal artery and superior ventricular septal arteries. Marked elastosis or atrophy was noted in the cases suffering from some long-standing disorder regardless of the sort of disorders. In the cases which were diagnosed as complete heart block clinically, destruction of the conduction tissues was extremely severe including those of the SA node.