Site of conduction delay in children with catheter-induced right bundle branch block

Eight cases of catheter-induced right bundle branch block (RBBB) in children during electrophysiologic studies are presented. Recording of right ventricular apical activation time (V-RVA) before and during the conduction delay allowed localization of the block along the course of the right bundle branch system. In the majority of patients, a significant lengthening of V-RVA was observed, indicating that proximal right bundle branch block is the most commonly induced type of conduction delay. Block was transient in all patients and terminated several minutes to 24 hours after its induction.