The deleterious effects of surgically induced complete right bundle branch block on long-term follow-up results of closure of ventricular septal defect.

The effects of complete right bundle branch block (CRBBB) on the early postoperative course and long-term follow-up results of closure of ventricle septal defect (VSD) were investigated. (1) Postoperative change in cardiothoracic ratio (CTR); In patients whose ratio of total pulmonary resistance to total systemic resistance (Rp/Rs) was larger than or equal to 0.33, CTR of the group with CRBBB did not decrease significantly (p greater than 0.1) but CTR of the group without CRBBB was improved markedly (p less than 0.01). However, in patients whose Rp/Rs was less than 0.33, there was no significant difference in CTR reduction between the two groups. (2) Postoperative change in Rp/Rs in patients with preoperative Rp/Rs larger than or equal to 0.33: In the group with CRBBB the Rp/Rs decreased from a preoperative average of 36 to 27 percent; in the group without CRBBB, it decreased from 39 to 21 percent. There were significant differences in both the postoperative value of RP/Rs and the degree of postoperative decrease in Rp/Rs between the two groups (both p less than 0.05). (3) Change of pulse rate in the early postoperative period: In patients with Rp/Rs larger than or equal to 0.33, the postoperative increase in pulse rate of the group with CRBBB was significantly higher than that of the group without CRBBB (p less than 0.05). These results suggest that CRBBB has a strong deleterious effect on right ventricular function. The possibility that CRBBB has an ill effect on left ventricular function in patients with Rp/Rs larger than or equal to 0.33 is discussed.