Correlative studies on electrocardiogram and histopathology of the conduction system. (1) Right bundle branch block with left axis deviation and prolonged P-R interval.

The conduction system was examined histologically in three cases whose electrocardiograms showed right bundle branch block and left axis deviation with or without PR prolongation. In two cases histological lesions were found in the right bundle branch and anterior division of the left bundle branch. In the third case histological lesions were found in the right bundle branch and anterior and posterior divisions of the left bundle branch. This case sufferred an Adams-Stokes attack. In the two patients with right bundle branch block and left axis deviation with PR prolongation, the PR prolongation was attributed to delay in atrioventricular node or His bundle in one case and to delay in left bundle branch in the other.