Decremental Conduction Property between Right Atrium and Superior Vena Cava Facilitates Detection and Mapping of the Caval Vein Potentials in Patients with Atrial Fibrillation

Purpose: Discriminating the potentials of superior vena cava (SVC) from those of right atrium (RA) at the venoatrial junction is sometimes challenging in patients with atrial fibrillation (AF) during SVC isolation. We aimed to establish a technique to identify clear potentials of SVC and RA at venoatrial junction. Methods: Twenty-five AF patients with SVC ectopy undergoing Catheter ablation were included. After pulmonary vein isolation, a circular decapolar Catheter and two multipolar Catheters were placed in the venoatrial junction, RA appendage and SVC, respectively. Burst pacing and single extrastimulus were applied from both RA appendage and SVC. Intervals of the potentials of RA and SVC on the circular Catheter during pacing maneuvers were measured. Results: Decremental conduction property in both directions between the venoatrial junction was observed with pacing maneuvers. The more decremental property was identified in the direction from RA to SVC than in the inverse direction. Single extrastimulus showed more decremental property than burst pacing either from RA appendage or SVC. Single extrastimulus facilitated identification of the earliest activation site of the venoatrial junction by separating the potentials of RA and SVC. Conclusions: Conduction over venoatrial junction showed decremental property, which facilitates mapping of the optimal ablation sites during electrical SVC isolation.