CBA procedure
All the procedures were conducted in local anesthesia with mild sedation. After access to the LA with the Brockenborough needle and an 8.5-French Swartz sheath (SL1; St. Jude Medical, MN), a 28-mm CB catheter (Arctic Front Advance; Medtronic Inc., MN) was introduced into the LA via a 12F steerable sheath (FlexCath; Medtronic Inc.). Mapping of the LA and PVs was performed with a circular mapping catheter (Achieve; Medtronic Inc.). The LA was reconstructed using the mapping catheter with the guidance of the 3-dimentional navigation system (KODEX-EPD Navigation system, version 1.4.8a). The technical characteristics of KODEX-EPD system have been described elsewhere7, 8.
Before delivering cryoablation, the Achieve catheter was positioned as proximal as possible in PV ostium to record PV potential. Then, the CB was inflated and advanced against the PV ostium. Baseline tool, injection tool and pulmonary venography were performed to assess the occlusion degree. (Figure 1)
The cryoablation strategy was 180 s in each PV with the following sequence: left superior PV (LSPV), left inferior PV (LIPV), right superior PV (RSPV), and right inferior PV (RIPV). To avoid phrenic nerve injury (PNI), all cryoapplicants for right PVs were performed while pacing at low output (4.0 mA and 1.0 ms duration) and clinical monitoring phrenic nerve function with tactile feedback. The nadir temperature and total thaw time of each freeze cycle were collected. Time to PVI (TTI) was also recorded if PV potential was visible during the cryoapplicants.