Delineation of the right ventricular septal activation during a right bundle branch origin accelerated idioventricular rhythm.

Accelerated idioventricular rhythm (AIVR) originating from the right bundle branch (RBB) (RBB-AIVR) is a rare ventricular arrhythmia. We delineated RBB and myocardial activation separately during RBB-AIVR, which revealed the spatial relationship of the AIVR origin, preferential pathway, and breakout site. Radiofrequency ablation to the preferential pathway successfully eliminated this arrhythmia.