Optimization of the generator settings for endobiliary radiofrequency ablation

Figure 1 Radiofrequency ablation on the ampulla of Vater. A: The introduction of the probe (pig #3); B: The early mucosal changes visible during radiofrequency procedure (pig #2); C: Features of early and excessive tissue damage after probe withdrawal (pig #1).

Figure 2 Macroscopic findings on the bile tract after radiofrequency ablation in pig #2. A: The papillary region and distal common bile duct, with tissue damage reaching the duodenal wall (arrows); B: An ablated zone limited to the wall of the common bile duct (arrows); C: An example of intrahepatic parenchymal damage up to 4 mm away from the bile ducts (arrows).

Figure 3 Histological findings in the three ampullae Vaterii treated by radiofrequency ablation. A: Taken from pig #3, shows satisfying ablation of the ampulla of Vater sparing the submucosa; arrows indicate the intact submucosa; hematoxylin eosin and saffron, original magnification × 25; B: The vertical extension of tissue damage in pig #1, reaching the muscularis mucosae; arrows indicate the muscularis mucosae; hematoxylin eosin saffron, original magnification × 100; C and D: The ampullae of pigs #1 and 2 (respectively), with deep tissue necrosis extending far beyond the muscularis propria up to the adipose tissue; arrows indicate the extent of coagulation necrosis; hematoxylin eosin and saffron, original magnification × 25.

Figure 4 Variation of the extent in depth of thermal tissue damage after radiofrequency ablation in the liver according to electrical settings (VIO 300D). A: Variation of depth with shot duration; B: Variation of depth with power output setting; C: Variation of depth with effect.

Figure 5 Relative variation of power output and effect setting for a given depth of tissue ablation and a 90 s ablation time in the liver.