Evolution of right bundle branch block and other intraventricular conduction abnormalities in the transplanted human...

We performed 12-lead electrocardiography (ECG) repeatedly in 13 patients with cardiac transplants. QRS block occurred at some point in 12 patients and its course was either sporadic, progressive, persistent or fluctuating (5, 3, 3 and 1 patient (s), respectively). In the first postoperative week, complete or incomplete right bundle branch block (RBBB) occurred in 10 patients. Left anterior fascicular block also occurred in 3 of the 10 patients. However, the block(s) subsided within 1 month in the 3 and 2 more patients. Nonspecific block, isolated left anterior fascicular block and left bundle branch block also occurred occasionally. QRS block was unrelated to the occurrence of cardiac rejection, catheter injury, right ventricular pressure or volume overloading, left ventricular function, and the length of ischemic time of the donor heart. Two patients have had permanent RBBB since the immediate postoperative period despite a normal donor electrocardiogram before harvesting. The temporal courses of QRS block varied widely in 9 patients. Thus, different mechanisms may have been active in various postoperative periods. The occurrence of QRS block was unrelated to morbidity and mortality in the recipients. Therefore, longer observation will likely establish the benign nature of the QRS block in this disease.