Fluoroscopy and ICE guide the clinician in making two transseptal punctures. Systemic anti coagulation begins after the first puncture, with a goal activated clotting time (ACT) of 300 to 400 seconds. An open irrigation, deflectable-tip catheter is used for mapping and catheter ablation. The previously taken MRI and CT images are incorporated into a three-dimensional mapping system for guidance as the pulmonary vein is isolated. During the procedure, fluoroscopy and computerized mapping systems track the catheter positions and permit precise delivery of radio frequency energy.