Postoperative trifascicular block complicating tetralogy of fallot repair.

Transient and residual conduction defects, including early and late complete heart block, are not uncommon in children following the intracardiac repair of tetralogy of Fallot. The case of a young girl is described, in whom early, transient complete heart block was found to be due to trifascicular damage. Through serial electrophysiological studies, gradual improvement in the conducting system was documented, although residual trifascicular damage remained. It is believed that all children with evidence of residual trifascicular damage are subject to possibly fatal bradyarrhythmias due to late postoperative complete heart block.