Safety and Efficacy of Endoscopic Liquid Nitrogen Spray Cryotherapy for Ablation at the Duodenal Papilla: A Survival Porcine Study: Presidential Poster

Abstract

Purpose: Endoscopic ampullectomy for premalignant lesions involving the duodenal papilla is associated with significant risks. Other endoscopic ablative modalities with less risk would be desirable. Endoscopic cryotherapy has been shown to be effective in the esophagus but there is no data on its safety and efficacy at the papilla due to the potential risks associated with liquid nitrogen expansion in the small intestine. The aim of this study was to assess the feasibility, efficacy and complications of liquid nitrogen spray cryoablation at the duodenal papilla in a porcine model. Methods: The study was approved by the Institutional Animal Care and Use Committee (IACUC) at our institution. Four 80-100 lbs pigs (sus) underwent liquid nitrogen spray cryotherapy (CSA Medical Inc, Baltimore, MD) at the duodenal papilla. Technical success was defined as successful placement of the cryotherapy decompression tube past the second portion of the duodenum, followed by delivery of liquid nitrogen spray to the duodenal papilla. Safety was determined by monitoring peri-procedural and post-treatment blood tests and clinical course. Clinical efficacy was established by histological evidence of cryogen-induced tissue injury. Cryoablation was initially tested in two non-survival pigs and subsequently assessed in two survival animals. In the survival studies, biopsies from the papilla were obtained prior to cryotherapy. Freeze time of 20 seconds was applied per cycle for a total of four cycles per session. All animals were monitored daily for post-treatment adverse events, based on signs of distress, behavior changes, and/or loss of appetite. Blood specimens were obtained prior to treatment, on post-ablation day (POD) #1 and #7 for evaluation of Hb, WBC, liver tests, and pancreatic enzymes. EGD was performed on POD#7 to assess the local effects of cryotherapy and to obtain biopsies for histology. All animals were euthanized at the end of the 1-week survival period and necropsy was performed. Results: Spray cryotherapy was technically successful in all 4/4 (100%) animals. Lab data showed no significant changes following cryotherapy when compared to baseline, except for transient AST elevation on POD#1 with normalization on POD#7 in one animal. The two survival animals thrived without any adverse events. There was no evidence of bleeding, infection (abscess), or bowel perforation on necropsy. Endoscopic evaluation on POD#7 showed edema and superficial ulceration at the duodenal papilla. Biopsies revealed inflammation and mucosal necrosis, consistent with successful cryogen-induced tissue injury. Conclusion: Our data suggests that endoscopic liquid nitrogen spray cryotherapy is feasible and safe for endoscopic ablation at the duodenal papilla in a porcine model.