Progressive improvement of His-Purkinje conduction during recovery from catheter-induced heart block.

Complete heart block developed during HBE studies in a patient with left bundle branch block, after inadvertent catheter-induced trauma to the right bundle branch. Normal intraventricular conduction (HV interval) was documented during the initial part of the study, and was demonstrated to be markedly prolonged after the appearance of heart block. Conduction through the right bundle branch improved over a short period of time as manifested by steplike shortenings of the HV interval, until the original conduction velocity was re-established. This case strongly supports the concept that the His-Purkinje system is capable of varying its conduction velocity and further demonstrates that, in patients with bundle branch block, a prolonged HV interval indicates disease of the remaining bundle branch.