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 <55°C and in 2 pigs sinus arrest occurred during o-RFA at 60°C. Histologically, transmural and circumferential contraction band necrosis was mainly confirmed around the SVCJ without damage to collateral tissue. In group 2, coagulation necrosis occupied almost all the ablative lesions, leading to severe degeneration of collateral tissue. Conclusion: O-RFA at the SVCJ may be more feasible and safer than RFA.