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Figure 4 Identification of a Trigger Originating in the Superior-Posterior Segment of the Left Superior PV

Panels A and B show the fluoroscopic image in LAO and RAO projections, respectively, of the catheter location. The circular catheter is placed in the left superior PV ostium and the ablation catheter is placed at the right carina. Panel C shows recordings from circular and ablation catheters. The earliest electrogram is noted in bipole 6 to 7 of the circular catheter (red arrow). Panel D shows the detail of the circular catheter in the left superior PV ostium in RAO projection. One can identify the origin of the trigger from the superior-posterior segment of that ostium. If the earliest bipole was localized to the carina region, maneuvers to rule out origin in the left inferior PV, placing the ablation catheter in its ostium during the induction, were done. Abbreviations as in Figures 1 and 2.