Key result
In 18 patients with surgical bifascicular block, 7 had A-V node or His-Purkinje disease, but the clinical course was benign over a mean 8.3 years, suggesting prophylactic pacemakers are not indicated.
Why the study?
Do electrophysiological abnormalities predict adverse clinical outcomes in patients with surgical bifascicular block after VSD or TF repair?
Cohort (n=18)
Do electrophysiological abnormalities predict adverse clinical outcomes in patients with surgical bifascicular block after VSD or TF repair?
Electrophysiological abnormalities are common in patients with surgical bifascicular block after VSD or TF repair, but their long-term clinical course is benign, suggesting prophylactic pacemakers are not indicated.
Small observational cohort suggests no prophylactic pacing after surgical bifascicular block; larger prospective studies needed to confirm.
Electrophysiological studies were performed in 18 patients who developed bifascicular block after repair of ventricular septal defect (VSD) or tetralogy of Fallot (TF). Two had transient complete heart block (CHB) in the immediate postoperative period. The P-A intervals were normal in all. A-H and H-V intervals were prolonged in three and four cases, respectively. Atrial pacing at progressively increasing heart rates was performed in 15 patients; two developed type II block distal to the His bundle (H). The effective and functional refractory periods (ERP and FRP) of the atrium (11 cases) were normal in all. The ERP of the A-V node (seven cases) was prolonged in found and the FRP was increased in three. The ERP of the ventricular specialized conduction system was measured in two cases and was prolonged in one. In all, seven cases had abnormalities indicating disease of the A-V node and/or His-Purkinje system. Recording of intervals, atrial pacing, and determination of refractory periods (RPs) was necessary to reveal all conduction abnormalities. One patient died of unrelated causes. The others are alive and in sinus rhythm with intact conduction 3 to 16.5 years following surgery (mean follow-up of 8.3 plus or minus 0.95 years). The clinical course in patients with normal and abnormal findings was equally benign. Prophylactic insertion of demand pacemakers does not appear indicated in these patients.
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Pahlajani et al. (1975) conducted a cohort in Bifascicular block after repair of ventricular septal defect or tetralogy of Fallot (n=18). Bifascicular block after VSD or TF repair was evaluated on Electrophysiological abnormalities and long-term clinical course. In 18 patients with surgical bifascicular block, 7 had A-V node or His-Purkinje disease, but the clinical course was benign over a mean 8.3 years, suggesting prophylactic pacemakers are not indicated.
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