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Figure 3 Detection of the exit breakthrough points in the right superior pulmonary vein (RSPV) by pulmonary vein (PV) distal pacing. Proximal (bipoles 7–8) electrograms from all splines of the basket catheter placed in the RSPV are shown. (Left panel) During sinus rhythm, atrial (A) and PV potentials approach each other. (Right panel) During PV distal pacing from A 1–2, these potentials are discriminated. The exit breakthrough point (*) is B 7–8.