Significance of electrical activity in the right superior pulmonary vein post-isolation and relationship to superior vena cava potentials

Purpose After antral pulmonary vein isolation (PVI), electrical potentials may persist deep in the right superior pulmonary vein (RSPV). Whether these potentials signify true pulmonary vein potential (PVP) (implying inadequate RSPV isolation) or are far-field potentials (FFP) from the superior vena cava (SVC) is unclear. Here, we attempt to assess the incidence of persistent potentials in RSPV post-isolation and methods to differentiate PVP from FFP. Methods Following PVI, we mapped the RSPV and the SVC with simultaneously placed catheters. We recorded the incidence of SVC potentials, RSPV potentials, and distance between the 2 structures. When RSPV potentials were present, we assessed (1) relationship to SVC potentials, (2) RSPV-SVC distance, and (3) responses on pacing from either site. Results Among 43 consecutive post-PVI patients, 39 (91%) patients had SVC electrical activity but only 10 had persistent RSPV potentials. Of these, 2/10 had true PVP, and 8 were FFP from SVC. Bipolar electrogram morphology did not differentiate PVP from FFP, but low-amplitude (5 mA) SVC pacing was an effective maneuver. However, high-amplitude (≥ 10 mA) pacing from SVC and/or RSPV could result in far-field capture of the other site even when RSPV was devoid of electrical activity. Average RSPV-SVC distance was 15.9 mm. Conclusions Persistent RSPV potentials occur rarely post-PVI despite the close proximity to electrically active SVC. When present, true PVP can be differentiated from FFP by low-amplitude pacing from SVC. Bipolar EGM morphology and high-amplitude pacing are unreliable at differentiating these potentials.