title: Are covered stents really effective at closing esophagotracheal fistulas? Results of an animal study.
abstract: OBJECTIVE
  To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas.
  
  
  METHODS
  Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically.
  
  
  RESULTS
  Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks.
  
  
  CONCLUSIONS
  This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.
authors.affiliation: Department of Diagnostic Radiology, Philipps University, Baldingerstrasse, D-35033 Marburg, Germany. wagnerh@mailer.uni-marburg.de
authors.forename: H J
authors.initials: HJ
authors.lastname: Wagner
authors.forename: B
authors.initials: B
authors.lastname: Stinner
authors.forename: P
authors.initials: P
authors.lastname: Barth
authors.forename: K J
authors.initials: KJ
authors.lastname: Klose
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D011140:Polyurethanes; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000295:instrumentation*; D011859:Radiography; D013193:Stainless Steel; D015607:Stents; D013556:Swine, Miniature; D014138:Tracheoesophageal Fistula / Q000000981:diagnostic imaging / Q000601:surgery*
chemical_list: D020099:Coated Materials, Biocompatible; D011140:Polyurethanes; D013193:Stainless Steel