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.