Endoscopic ultrasound-guided application of a new hybrid cryotherm probe in porcine pancreas: a preliminary study

Background and study aims: Open, laparoscopic, or percutaneous radiofrequency (RF) ablation of the pancreas is still dangerous, whereas endoscopic ultrasound (EUS)-guided ablation might reduce risk because it is less invasive and provides real-time monitoring. We aimed to demonstrate the feasibility of transluminal RF ablation and to evaluate the efficacy and safety of a new flexible bipolar ablation probe combining RF and cryotechnology. Methods: 14 ablations were performed in 14 pigs. Energy input (16 W) and simultaneous cryogenic cooling with carbon dioxide (650 psi) were standardized. Application time range was 120900 seconds. Ablation area was measured by EUS immediately after ablation (area TO), and before euthanasia (area T1). Macroscopic findings (area T2) and histological findings after necropsy served as gold standard. The interval from application to euthanasia was either 1 or 2 weeks. Results: The correlation between EUS findings (area T1) and macroscopic appearance (area T2) was good (R = 0.89). The correlation between the T2 ablation area and the application time showed a fitted ratio of 2.3 (P < 0.0001) with a 1-week interval and 0.2 (P= 0.01) with a 2-week interval. No pig died because of the procedure. Two pigs showed histochemical pancreatitis, which was clinically overt in one. Necropsy additionally revealed one burn to the gastric wall and four gut adhesions. Conclusions: Selective transluminal RF ablation of the pancreas under EUS control in a living pig model is feasible. The new flexible bipolar probe creates an ablation area with extent related to the duration of application, and with fewer complications than conventional RF ablation techniques.