3.2. Ablation procedure
Electrophysiological studies and catheter ablation were performed by four experienced operators (M.M, T.K, A.S, and Y.M) with the patient under intravenous sedation with dexmedetomidine. The operator performed the mapping and ablation under guidance with an electroanatomical mapping system (Carto3®; Biosense Webster, Diamond Bar, CA, USA).
First, PVI was performed using an open-irrigated ablation catheter (Thermocool SmartTouch®, Biosense Webster), a cryoballoon (Arctic Front Advance®, Medtronic, Minneapolis, MN, USA), or a laser balloon (HeartLight®, CardioFocus, Marlborough, MA, USA). When a radiofrequency catheter was used, a dragging technique was employed to perform circumferential ablation around both ipsilateral pulmonary veins. Radiofrequency energy was applied for 30 s (15 s at the posterior left atrial wall near the esophagus) at each site using a maximum temperature of 42 °C and maximum power of 35 W. Irrigation rate was 17 ml/min. The operator attempted to maintain an appropriate contact force between the catheter and endocardium of 5 to 20 g. In cases using a cryoballoon, 180-sec freezing was applied using a 2nd generation 28-mm cryoballoon catheter. The laser balloon was inflated with the goal of complete occlusion of the PV ostium. Laser lesions were created with a 30–50% lesion overlap. Where very good tissue contact was obtained, maximal power (12 W for 20 seconds) was chosen. At regions with moving blood, laser energy was applied at 7 W for 30 seconds.
PV electrograms were recorded using a 20-pole circular mapping catheter (LassoNaV, Biosense Webstar). PVI was considered complete when both entrance and exit blocks were created. If atrial flutters or non-PV AF triggers were observed spontaneously or induced by atrial burst stimuli or isoproterenol infusion, additional ablation were performed.