Right bundle branch block and cardiac infarction.

It is the object of this paper to investigate the modifications of the electrocardiographic pattern of cardiac infarction caused by the simultaneous presence of right bundle branch block, and to describe the cardiographic signs on which the diagnosis of infarction can be made in the presence. of right branch block. The cardiogram of right branch block shows added changes characteristic of infarction; it differs in this respect from that of left branch block which often masks the evidence of infarction. An analysis of tracings taken from patients with right bundle branch block but without infarction will be necessary for the study of cardiograms showing the combined lesion and will, therefore, precede it. All cases under review have the cardiographic pattern of the common variety of right branch block; cases of classical right branch block, characterized by a predominantly downward directed main deflection in lead I, a conspicuous R in lead II, and a tall R in lead III, with T waves in the opposite direction of the main deflection, were not included because of their rarity. A series of twenty-three patients were observed personally; the majority were seen in private practice, and their tracings were taken with a Siemens electrocardiograph; seven patients were seen at the Out-Patient Department of the National Heart Hospital, under Dr.