Cryoballoon (CB) ablation:
After a trans-septal puncture at the fossa ovalis, a long deflectable sheath (FlexCath Advance sheath; Medtronic, Inc, Minneapolis, MN) was introduced into the LA using intracardiac echocardiographic guidance. Pulmonary venous angiograms were obtained for each of the four PVs to serve as a fluoroscopic reference. An endocardial map of the LA was created via a CARTO-Biosense (Carto [R] 3; Biosense Webster, Inc, Diamond Bar, CA) or Ensite system (NavX, St. Jude Medical, Inc, St. Paul, MN). Right-sided phrenic nerve (PN) pacing was performed during the ablation of the right PVs. A second-generation CB catheter with a 23- or 28-mm balloon (Arctic Front Advance, Medtronic) and a PV mapping catheter were passed into the LA via the long sheath. Cryo lesions were targeted to the PVs after the demonstration of balloon occlusion with contrast injection. Goal temperatures were between -35 to -55C. Freezes were aborted if the esophageal temperature fell below 28°C or if phrenic nerve pacing showed diminution of diaphragmatic excursion during right-sided PV lesion delivery. Following the delivery of at least two lesion sets per vein, electrical isolation of each PV was reassessed, and additional applications of cryotherapy were delivered with either a 23- or 28-mm second-generation CB as necessary.