Endoscopic cryotherapy: experimental results and first clinical use

Background: Cryotherapy or the application of extreme cold has many potenti al applications in gastroenterology including tissue destruction and hemost asis but until now its development has been prevented by the lack of a deli very device suitable for use through the endoscope. We report here our expe rience with prototype devices using both liquid nitrogen driven by a cryosu rgical system and cryogenic refrigerants (nitrous oxide and carbon dioxide) at or near ambient temperature. Methods: Cryotherapy was applied to the distal esophageal mucosa of dogs vi a a flexible catheter passed through an upper endoscope. In other dogs, cry otherapy was used for hemostasis in a bleeding ulcer model. The procedure w as also used for palliation in a 58-year-old man with unresectable adenocar cinoma of the stomach with pyloric channel obstruction. Results: Freezing of the superficial mucosa was nearly instantaneous. All d ogs survived the procedure and appeared to thrive. Histologic evaluation re vealed significant necrosis of the superficial epithelial layer accompanied by a fibrinocellular infiltrate on the surface. These markers of acute inj ury subside by the fourth to sixth day and are replaced by regenerating epi thelium, a process that is virtually complete by day 10. In the hemostasis experiments, bleeding ceased immediately after cryospraying of the lesions but resumed on thawing in most cases. Application of cryotherapy in the pat ient resulted in reduction of the pyloric mass with no immediately apparent adverse effects. Conclusions: These data, although preliminary, demonstrate the feasibility of endoscopic cryotherapy using a simple hand-held device. This device has broad potential for use in gastroenterology including ablation of superfici al epithelium, debulking of large tumors and hemostasis.