Cryoballoon Ablation Procedure:
All procedures were performed under general anesthesia. Briefly, utilizing a femoral venous approach, two sheaths (7Fr and 9Fr) were placed in the left femoral vein. Via these sheaths, a Livewire decapolar catheter and an Intracardiac Echocardiography (ICE) catheter (both St. Jude Medical, St. Paul, MN) were advanced into the right atrium (RA) and subsequently positioned under fluoroscopic guidance in the coronary sinus and RA, respectively. A transseptal sheath was placed in the right femoral vein. Using ICE and fluoroscopy guidance, trans-septal access to the LA was obtained. A heparin bolus was given prior to trans-septal puncture and then as needed to maintain the activated clotting time (ACT) greater than 300 seconds during the procedure. The transseptal sheath was then exchanged for a 12 Fr Flexcath sheath through which a 28 mm Artic Front Advance Cryoballoon ablation catheter (both Medtronic, Inc., Minneapolis, MN) along with an inner lumen Achieve spiral mapping catheter (Medtronic, Inc.) were placed in the LA. Using the St. Jude Medical Ensite Velocity NAVX software, guided by a three dimensional CT recreation of the LA, electroanatomic mapping was performed in the LA to identify all the PVs. Each of the PVs were then sequentially isolated using cryoballoon insufflations after ensuring tight contact with their respective antrums. During cryoablation of the right-sided PVs, the livewire catheter was used to stimulate the phrenic nerve from the SVC to monitor for phrenic nerve injury. Following cryoablation, a bidirectional conduction block was demonstrated from all veins, and a post-ablation voltage map was created using the NAVX software. For areas noted to have incomplete PV isolation with electrical gaps, additional touch up freezes with the cryoablation catheter or, if necessary, a RF ablation catheter was performed. For LCPVs with large ostiums, a segmental approach was utilized with multiple cryoablation applications delivered around the circumference of the PV antrum in order to achieve antral isolation of the common vein. Additional cryoablation applications or additional RF ablation was performed as needed until complete PV isolation was achieved from all veins.