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 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 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 PN 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 delivered with either a 28 or 23 mm second-generation CB as
necessary.