title: Experimental trial of balloon-expandable, metallic Palmaz stent in the trachea.
abstract: OBJECTIVE
  To determine the effect of the Palmaz stent, which has been successfully used to relieve airway obstruction in a small group of children, on the normal and operated on animal trachea.
  
  
  METHODS
  In this experimental trial, stents were placed bronchoscopically in the thoracic tracheae of 4 groups of 50 anesthetized cats. The cats in group 1 (adults, n = 10) and group 2 (kittens, n = 10) had normal tracheae; the cats in group 3 (adults, n = 15) underwent horizontal tracheal incision and closure; and the cats in group 4 (adults, n = 15) underwent pericardial patch tracheoplasty. In group 3 and 4, the stents were inserted in 10 cats and 5 cats served as controls. Stents were inflated to a 15-mm diameter in group 1 and an 8-mm diameter in the other groups. Half of the animals with stents were killed 5 weeks after the procedure, and the others, 10 weeks after the procedure.
  
  
  METHODS
  The Hospital for Sick Children, Toronto, Ontario.
  
  
  RESULTS
  In group 1, 1 animal died of tracheal perforation. A mild cough was noted in 15 of the 39 cats with stents. In group 4, 3 cats had difficulty eating and lost weight. The results of esophagoscopy excluded esophageal inflammation or obstruction in these 3 animals. The results of bronchoscopy indicated a nonobstructing rim of granulation tissue at the end of the stent in 15 of 20 cats in groups 1 and 2 and 17 of 20 cats in groups 3 and 4 and at the repair site in all animals with stents from groups 3 and 4. The results of autopsy indicated the cross-sectional area at the site of the stent was greater than normal in group 1 (P < .003) and smaller than the normal trachea at the site of the tracheoplasty in group 4 controls without stents (P < .02); however, the cross-sectional area at the tracheoplasty site with the stent was not smaller (P < .13). The results of histologic examination indicated a mild inflammatory reaction, with granulation tissue in all animals with stents, but in group 1, with overexpanded stents, the reaction was more severe, with epithelial ulceration, fibrosis, and sealed-off perforations in most animals. In group 3, the tracheae with stents had significantly more inflammatory reaction, granulation tissue, and epithelial damage than the controls without stents.
  
  
  CONCLUSIONS
  The Palmaz stent provokes an inflammatory reaction in the normal trachea and the trachea recently operated on. With the exception of the group 1 animals with overexpanded stents, this reaction is clinically insignificant. The Palmaz stent is able to maintain a normal lumen size after pericardial tracheoplasty in cats.
authors.affiliation: Department of Surgery, University of Toronto, Hospital for Sick Children, Ontario.
authors.forename: J C
authors.initials: JC
authors.lastname: Fraga
authors.forename: R M
authors.initials: RM
authors.lastname: Filler
authors.forename: V
authors.initials: V
authors.lastname: Forte
authors.forename: A
authors.initials: A
authors.lastname: Bahoric
authors.forename: C
authors.initials: C
authors.lastname: Smith
mesh_terms: D000800:Angioplasty, Balloon / Q000295:instrumentation*; D000818:Animals; D020680:Bronchoscopes; D002415:Cats; D005260:Female; D006097:Granulation Tissue / Q000473:pathology; D008297:Male; D011859:Radiography; D015607:Stents / Q000009:adverse effects* / Q000706:statistics & numerical data; D014132:Trachea / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D014136:Tracheitis / Q000209:etiology / Q000473:pathology