title: Endoscopic cryotherapy: experimental results and first clinical use.
abstract: BACKGROUND
  Cryotherapy or the application of extreme cold has many potential applications in gastroenterology including tissue destruction and hemostasis but until now its development has been prevented by the lack of a delivery device suitable for use through the endoscope. We report here our experience with prototype devices using both liquid nitrogen driven by a cryosurgical 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 via a flexible catheter passed through an upper endoscope. In other dogs, cryotherapy was used for hemostasis in a bleeding ulcer model. The procedure was also used for palliation in a 58-year-old man with unresectable adenocarcinoma of the stomach with pyloric channel obstruction.
  
  
  RESULTS
  Freezing of the superficial mucosa was nearly instantaneous. All dogs survived the procedure and appeared to thrive. Histologic evaluation revealed significant necrosis of the superficial epithelial layer accompanied by a fibrinocellular infiltrate on the surface. These markers of acute injury subside by the fourth to sixth day and are replaced by regenerating epithelium, 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 patient 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 superficial epithelium, debulking of large tumors and hemostasis.
authors.affiliation: Division of Gastroenterology and Hepatology, University of Texas Medical Branch, Galveston, Texas 77555-0764, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Pasricha
authors.forename: S
authors.initials: S
authors.lastname: Hill
authors.forename: K S
authors.initials: KS
authors.lastname: Wadwa
authors.forename: G T
authors.initials: GT
authors.lastname: Gislason
authors.forename: P I
authors.initials: PI
authors.lastname: Okolo
authors.forename: C A
authors.initials: CA
authors.lastname: Magee
authors.forename: M I
authors.initials: MI
authors.lastname: Canto
authors.forename: W H
authors.initials: WH
authors.lastname: Kuo
authors.forename: J G
authors.initials: JG
authors.lastname: Baust
authors.forename: A N
authors.initials: AN
authors.lastname: Kalloo
mesh_terms: D000230:Adenocarcinoma / Q000628:therapy; D000818:Animals; D017679:Cryotherapy / Q000295:instrumentation / Q000379:methods*; D004195:Disease Models, Animal; D004285:Dogs; D020776:Endoscopes, Gastrointestinal; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D004867:Equipment Design; D004947:Esophagus / Q000473:pathology; D017809:Fatal Outcome; D006801:Humans; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000473:pathology; D010438:Peptic Ulcer Hemorrhage / Q000628:therapy; D011708:Pylorus; D013274:Stomach Neoplasms / Q000628:therapy; D013276:Stomach Ulcer / Q000150:complications / Q000628:therapy