Use of multielectrode circular mapping catheter to guide electrical isolation of the right superior pulmonary vein (RSPV). Panel A shows left anterior oblique fluoroscopy view of the left atrium during contrast injection of the right superior pulmonary vein. Panel B shows same view with circular mapping catheter (CMC) inserted just inside the ostium of the RSPV, with the ablation catheter (Abl) deployed near the venous ostium to complete electrical isolation of the vein. CS indicates the coronary sinus catheter; T, radio-opaque temperature probe; His, the His bundle catheter.