Evaluating the tissue effects of balloon-based endobiliary radiofrequency ablation in porcine bile ducts

Background We developed a novel balloon-based endobiliary radiofrequency ablation (RFA) system to overcome the limitations of conventional RFA in treating malignant biliary strictures. This study aimed to evaluate the histological effects of balloon-RFA in porcine bile ducts. Methods Balloon-RFA of intrahepatic bile ducts from freshly resected porcine livers was performed for 60 s at 50, 60 and 70 °C. The specimens were subsequently sectioned for histological analysis and the slides were digitally scanned. Pseudo-coloring was applied based on the intensity of the ablation effect, and the area and estimated volume of ablation were measured. Results All samples showed epithelial sloughing and coagulative necrosis, and the entire internal circumference of the bile duct was evenly ablated. Complete transmural necrosis and involvement beyond the wall were found in 0% of samples ablated at 50 °C, in 33% at 60 °C and 100% at 70 °C. The mean depth and estimated volume of the ablation areas were 1.29 mm and 353.84 mm3, 1.44 mm, and 505.54 mm3 and 1.81 mm and 702.52 mm3 at 50, 60 and 70 °C, respectively. Conclusions Balloon-RFA leads to sloughing of the mucosa and coagulative necrosis. Ablation depth and volume increased in proportion to target temperature