Purpose: Endobiliary radiofrequency ablation (RFA) is a new endoscopic ablative technique. However, the ideal power setting for RFA has not yet been clarified. Therefore, we intended to evaluate the effects of endobiliary RFA according to time variations using novel RFA. Materials and methods: Nine female pigs were divided into three groups according to ablation time (60, 90, and 120 seconds) with the same setting (10 watts, 80 °C). All pigs underwent endoscopic retrograde cholangiography (ERC) and endobiliary RFA in the common bile duct. Gross and histologic examinations were performed after 24 hours. Results: The ERC and application of the endobiliary RFA were 100% successful, and the post-RFA cholangiogram did not show contrast leakage. The median depth of microscopic ablation was significantly different among the three groups (60 vs. 90 vs. 120 seconds = 1.90 (1.17-2.23) vs. 2.44 (2.31-2.60) vs. 2.52 (2.47-2.64) mm, p = 0.018). There was also a linear relationship between ablation time and microscopic ablation depth (r2 = 0.552, p = 0.002). However, no significant differences in macroscopic or microscopic ablation length were observed. In addition, there were focal ablation injuries in adjacent liver tissue in five of the nine pigs (2/3 in 60, 1/3 in 90, and 2/3 in 120 seconds). Conclusion: Endobiliary RFA using a novel RFA catheter resulted in controlled ablation with a linear relationship between microscopic ablation depth and ablation time in a swine model. Clinical studies are needed to validate the safe energy condition of endobiliary RFA in malignant biliary obstruction.
Keywords: animal experiment; endobiliary radiofrequency ablation (endobiliary RFA); endoscopic retrograde cholangiography (ERC); radiofrequency (RF); radiofrequency ablation (RFA); swine.