Ablation Procedure
All patients underwent the ablation procedure with general anesthesia. All patients underwent detailed EAM with either CARTO or ESI mapping systems following vascular and left atrial access prior to and following ablation. Patients presenting in AF underwent cardioversion to NSR prior to EAM. All patients underwent PVI as the principle ablative strategy of the procedure. Additional non-PV targets (linear lesions; low-voltage areas) were ablated at the operator’s discretion.
Catheter ablation was performed using either an irrigated, contact force-sensing RF ablation system (Biosense Webster, etc., or Abbot/ESI) or a cryoballoon ablation catheter (Arctic Front and Arctic Front Advance, Medtronic Inc.). For patients undergoing RF ablation, target power delivery to the anterior and posterior LA walls was 35–45 and 25–35 W, respectively. Patients undergoing cryo-balloon ablation underwent fluoroscopic positioning of a 28- or 23mm cryo-balloon to achieve complete PV occlusion assessed by contrast injection. A minimum of two freeze-thaw cycles (3 min duration) were applied to each vein, sufficient to achieve PV isolation as assessed by a multipolar mapping catheter.
All patients had an esophageal temperature probe in place during ablation, with temporary cessation of lesion application if esophageal temperature deviation occurred. Phrenic nerve pacing was performed during cryo-balloon ablation in right-sided pulmonary veins in all cases, with cessation of ablation upon any diminution in the force of diaphragmatic contraction.
PV isolation was assessed in all cases after a 20-minute waiting period by demonstrating an entrance block to each vein, assessed during sinus rhythm on post-ablation EAM. Exit block was demonstrated at the operator’s discretion, as was occult PV reconnection during adenosine infusion.