Lesions of conduction tissue complicating aortic valvular replacement.

A pathologic study of the cardiac conduction system was performed in 57 patients who died within 30 days after aortic valvular replacement. Histologically, there were old and recent lesions present in 34 (60 percent) and 43 (75 percent) of the patients, respectively. Old lesions did not show meaningful correlation with preoperative electrocardiograms. Although nontraumatic recent lesions were rarely the cause of postoperative abnormal cardiac conduction, traumatic lesions were frequently associated with loss of sinus mechanism. The main cause of trauma to the major cardiac conduction tissue was injury by sutures. The short membranous septum predisposed to injury, while the configuration of the left ventricular outflow tract was not a significant factor in injury. Traumatic lesions of the cardiac conduction tissue were more common in subjects with bicuspid than tricuspid aortic valves.