Surgically Induced Right Bundle-Branch Block with Left Anterior Hemiblock

A review of the electrocardiograms of 291 patients who survived more than 1 month after complete repair of tetralogy of Fallot disclosed that 24 (8.2%) developed a pattern of right bundle-branch block and left anterior hemiblock (RBBB-LAH) following surgery. When the course of these 24 patients was compared with a control group of 100 additional patients who did not develop this pattern following surgery, a significant increase in morbidity and mortality was noted.Complete heart block developed at some time in the follow-up period in 41.7% of the RBBB-LAH group and in 4% of the control group. The incidence of serious ventricular arrhythmias was 16.7% for the RBBB-LAH group and 1% for the control group. Sudden death occurred in 12.5% of the patients with RBBB-LAH and in 2% of the controls. At the time of this review (1-12 years following surgery) overall late mortality was 25% for the RBBB-LAH group and 2% for the control group.The study indicates that serious complications are much more frequent in tetralogy of Fallot patients who acquire the RBBB-LAH pattern during surgical repair. Prophylactic or therapeutic pacing may be indicated in many of these patients.