Electrophysiological and Histological Evaluation of Acute Efficacy and Safety of Balloon Occlusive Ablation at Superior Vena Cava-Right Atrial Junction

We evaluated efficacy and safety of occlusive radiofrequency catheter ablation (o-RFA) using our thermal balloon catheter (TBC) at superior vena cava (SVC)-right atrial (RA) junction (SVCJ) compared to that of RFA with a standard-tip catheter. Methods: To electrically isolate (SVCI) SVC from RA in 10 pigs (group 1), the initial o-RFA at a balloon surface temperature of 53.9 ± 3.0°C for 3–5 min (13.56 MHz) was achieved at the SVCJ completely obstructed with an inflated balloon. If unsuccessful, subsequent o-RFA was repeated in a ࣘ5°C increments until reaching either SVCI or sinus arrest. Before and after each o-RFA, stimulation protocol from the RA was performed. Additionally, in 5 different pigs (group 2), RFA at 55°C (ࣘ50 W) for 1 min with a 4 mm-tip catheter was achieved at multiple sites along the SVCJ. Finally, the neighboring tissues of the SVCJ were histologically investigated. Results: In group 1, successful SVCI could be easily accomplished at the final temperature of 57.2 ± 2.4°C; however, in 3 pigs, a new atrial tachycardia was induced after o-RFA at