Endoscopic cryotherapy: Preliminary results of a new technique for tissue ablation and hemostasis in the gastrointestinal tract

Background. Cryotherapy is based on the principle that short applications of extreme cold can produce localized tissue destruction. The depth of injury can be precisely controlled rendering it particularly suitable for the treatment of superficial dysplasic/neoplastic or vascular lesions. Despite its obvious potential in gastroenterology, the use of cryotherapy in therapeutic endoscopy has not been seriously investigated. We have developed a prototype endoscopie device (Cryospray) that permits the delivery of liquid cryogens in the form of a spray. Aim. To test the feasibility of using this procedure for superficial tissue ablation and hemostasis in the gastrointestinal tract. Methods. The cryospray device consisted of a long, flexible and insulated catheter through which liquid nitrogen (-196° C) was driven by a cryosurgical system (CMS Inc., Rockville). This catheter was passed through the biopsy channel of a therapeutic upper endoscope that was positioned several cm away from the target lesion. In the first set of experiments, liquid nitrogen was sprayed at the distal esophageal mucosa of 5 dogs. Dogs were then re-endoscoped periodically and biopsies taken from the treated areas. In other dogs, cryotherapy was used for hemostasis in a bleeding ulcer model. Results. Freezing of the esophageal mucosa, with a sharp demarcation margin from untreated mucosa, was visible within seconds of spraying liquid nitrogen. This was followed by slow thawing over the next few minutes. All dogs survived the procedure and appeared to thrive. At 24 hours, the epithelium was completely sloughed off with preservation of the submucosa and deeper layers. No significant hemorrhage was seen. By 3 weeks, the esophagus was completely re-epithelialized in 3 of 4 animals. In the hemostasis experiments, bleeding ceased immediately after cryospraying of the lesions, but resumed upon thawing in most cases. Conclusions. We have demonstrated the feasibility of endoscopie cryotherapy with several exciting implications for gastroenterologists. Its ability to cause a controlled depth of injury that is avascular may make it particularly valuable for treating superficial lesions such as Barrett's and AVMs. Further, it may also serve as a useful adjunctive measure in the treatment of bleeding lesions (such as varices) by virtue of its ability to produce a rapid cessation of bleeding from a distance.