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.