Demonstration of entrainment and presence of slow conduction during ventricular tachycardia in arrhythmogenic right ventricular dysplasia.

During VT in two cases with arrhythmogenic right ventricular dysplasia, entrainment criteria, constant fusion beats except for the last entrainment beat, progressive fusion, and a localized conduction block associated with interruption of VT, were demonstrated with rapid ventricular pacing performed during VT. Furthermore, a long conduction interval was present during entrainment from the pacing site to the earliest activation site during VT, indicating the presence of a slow conduction area. VT in these cases was, thus, due to reentry with an area of slow conduction within the circuit.