Visualization of the electrophysiologically defined junction between the superior vena cava and right atrium

An electrical superior vena cava (SVC) isolation from the right atrium (RA) sometimes can be challenging. For a safe and efficient SVC isolation, we aimed to visualize the accurate position of the SVC-RA junction on a three-dimensional (3D) mapping system using the decremental conduction properties of the SVC-RA junction in patients with atrial fibrillation (AF).

This study consisted of 15 consecutive AF patients (11 males, age 59 ± 10 years). A 3D mapping catheter was positioned in the SVC-RA junction region while delivering a single extra-stimulus from the right atrial appendage (RAA), to discriminate the RA and SVC potentials. The electrophysiological SVC-RA junction was defined as the most proximal points where the SVC potentials were recorded, which were tagged on the 3D mapping system around the SVC-RA junction, where radiofrequency energy applications were applied.

Around the SVC-RA junction, 9 ± 2 points were tagged on the 3D mapping system. The highest and lowest SVC-RA junction points were located on the anterior wall and posterior wall, respectively. The difference in the level between the highest and lowest SVC-RA junction points was 16.2 ± 6.3 mm. A successful SVC isolation was obtained in all patients without any complications.

The plane of the electrophysiologically defined SVC-RA junction was not perpendicular to the body axis, but slanted due to the anterior side being higher. Recognizing the precise location of the SVC-RA junction would contribute to a safe and efficacious SVC isolation.