Endoscopic Ultrasound-Guided Application of a Cryotherm® Probe in the Pancreas : Results in an Animal Model

Context The development of linear array therapeutic probes with a large working channel (3.8 mm) has made endoscopic ultrasound (EUS) more operative. Objective The aims of the study were to evaluate feasibility, efficacy, and safety of EUS-guided transgastric application of a new cryotherm probe (CTP) in the pancreas of an animal model, as well as to objectify risks, complications and histological changes. Methods A new hybrid ablative device that combines radiofrequency (RF)-ablation with cryotechnology has been developed by ERBE. The cryotechnology has been used to support and increase the killing effect of the RF-technology. A Hitachi ultrasonographic system and a linear array Pentax EG3830UT echoendoscope were used. The CTP was applied under EUS guidance in 19 domestic pigs. The animals were killed immediately (n=1), one week (n=10), two weeks (n=7) and 4 weeks (n=1) after ablation. Pathologic examination was performed. Results All pigs tolerated the procedure well. Correlation between EUS and gross pathology showed a correlation coefficient of 0.69. Excluding an animal with severe pancreatitis, the correlation coefficient was 0.87. The ablation area was correlated to the application time and measured by means of the robust regression: it showed a fitted ratio of 2.294 (P<0.001), in the pancreases of the animals killed after one week, 2.709 in the pig immediately killed (P<0.001) and 0.209 in the animals killed after 2 weeks (P<0.001). Three animals presented a burning of the gastric wall, one developed a fistula between the cystic lesion and the gut, two had acute pancreatitis. Conclusion This is the first device which combines radiofrequency and cryotechnology to create selective necrosis. We demonstrated the feasibility, efficacy and safety of its EUS-guided application in the pancreas in a porcine model.