Introduction:
Pulmonary vein (PV) ectopy is understood to represent the bulk of triggers for atrial fibrillation.1 Electrical isolation by demonstration of entrance and exit block in these structures is the cornerstone of the catheter based therapy for this arrhythmia.2
Rate dependent conduction block is a well described electrophysiological phenomenon. This is often seen physiologically in the normal conduction system (e.g. a long-short inducing a RBBB, or AV Wenckebach at rapid heart rates). Rate dependent block across the cavo-tricuspid isthmus has been well described after catheter ablation of atrial flutter. It is believed to increase the likelihood of recurrence and, consequently, rate independent block has been supported as the end point for this ablation. Rate dependent block across the pulmonary veins has been previously described immediately following catheter ablation. Jacobson et al3 has previously described rate dependent entrance block (LA:PV) and Yagashita et al4 described rate dependent exit block (PV:LA). We report the case of rate dependent PV block seen at repeat ablation 7 years after the index procedure.