Radiofrequency ablation of the pancreas. I: Definition of optimal thermal kinetic parameters and the effect of simulated portal venous circulation in an ex-vivo porcine model.

CONTEXT Radiofrequency ablation of pancreatic tumours carries a risk of injury to important structures such as the bile duct and duodenum. We have recently developed an ex-vivo model of radiofrequency ablation of the porcine pancreas. OBJECTIVE This study evaluates the effect of variations in probe temperature, duration of ablation and simulated portal venous flow on radiofrequency-induced injury. SPECIMEN RETRIEVAL: Pancreata of 30 6-month-old healthy pigs undergoing sacrifice in a commercial abattoir were used. INTERVENTIONS Radiofrequency energy was applied to a pre-marked area of the pancreatic head. Pancreatic head biopsies were taken after ablation to incorporate duodenum, portal vein and bile duct respectively and frozen in liquid nitrogen. For each experiment a portion of the tail of the pancreas was studied as non-ablated control. Paired slides using haematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide (NADH) stains were prepared. MAIN OUTCOME MEASURES The effects of variation in target temperature (100 degrees C to 80 degrees C), duration of ablation and of simulated portal perfusion were studied. RESULTS Optimal thermal kinetic characteristics were produced by a target temperature of 90 degrees C applied for 5 minutes. At this temperature there was ablation of pancreas without injury to adjacent viscera. Higher temperatures resulted in injury to the bile duct and portal vein. Simulated portal circulation had no effect on ablation. CONCLUSIONS In this ex-vivo study radiofrequency produced a temperature and duration dependent ablation with the optimal characteristics being 90 degrees C for 5 minutes.