Case Report Spontaneous Documentation of Bidirectional Block During Pulmonary Vein Isolation- Keep an Eye on the Electrograms!

In the present case, we describe the abrupt transformation of intra-pulmonary vein activity from rapid firing to dissociated ectopic activity during sinus rhythm, as an easily identifiable, though rare to encounter, sign which documents the achievement of bidirectional block. Key Words: bidirectional block, pulmonary vein, ablation, atrial fibrillation A 47-year old patient underwent a catheter ablation procedure due to recurrent, symptomatic, drug-resistant episodes of atrial fibrillation. The ablation strategy included pulmonary vein (PV) isolation by deployment of circumferential lesions surrounding the PVs with an irrigated ablation catheter (Navistar Thermocool SF, Biosense Webster, inc., Diamond Bar, CA) and the use of a three-dimensional electroanatomical mapping system (CARTO-3). A circula