Fluoroscopy image in anterior posterior view. Both the ablation catheter and the circular mapping catheter are inserted into the left atrium and positioned at the ostium of the left superior pulmonary vein after successful double transseptal puncture of the interatrial septum. Esophageal position is monitored using a contrast dye-filled nasogastric tube. ABL, ablation catheter; LASSO, circular mapping catheter; CS, coronary sinus catheter; NG, nasogastric tube.