title: Covered retrievable tracheobronchial hinged stent: an experimental study in dogs.
abstract: OBJECTIVE
  To evaluate the safety and technical feasibility of the use of a covered retrievable tracheobronchial hinged stent and investigate the histopathologic airway changes after placement and removal of the stent in dogs.
  
  
  METHODS
  The experimental stent was composed of tracheal and bronchial stents that were connected together at their ends. Each stent was woven from a single thread of 0.2-mm-diameter nitinol wire filament in a tubular configuration and covered with polyurethane solution by a dipping method. Drawstrings were attached at the upper end of the tracheal stent for stent removal. Under fluoroscopic guidance, 20 stents were placed at the lower trachea and left main bronchus in 20 dogs and were electively removed 4 weeks (n = 10) or 8 weeks (n = 10) after placement. Ten dogs were killed just after stent removal and the remaining 10 were killed 2 weeks after stent removal.
  
  
  RESULTS
  Stents were successfully placed in all dogs. Pneumonia was observed in three dogs. Stent migration occurred in seven dogs (35%). Except for two cases of stent expectoration, 18 stents were easily removed within a few minutes. There was considerable granulation tissue proliferation and inflammatory reaction in the airways of the dogs that were killed just after stent removal. The pathologic changes of the airways returned to almost-normal conditions 2 weeks after stent removal.
  
  
  CONCLUSIONS
  Placement and removal of a covered retrievable tracheobronchial hinged stent seems to be feasible, and histopathologic changes of the airway related to the stents returned to normal 2 weeks after stent removal.
authors.affiliation: Department of Diagnostic Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul. jchwang@uuh.ulsan.kr
authors.forename: J C
authors.initials: JC
authors.lastname: Hwang
authors.forename: H Y
authors.initials: HY
authors.lastname: Song
authors.forename: S G
authors.initials: SG
authors.lastname: Kang
authors.forename: J H
authors.initials: JH
authors.lastname: Suh
authors.forename: G Y
authors.initials: GY
authors.lastname: Ko
authors.forename: D H
authors.initials: DH
authors.lastname: Lee
authors.forename: T H
authors.initials: TH
authors.lastname: Kim
authors.forename: Y K
authors.initials: YK
authors.lastname: Jeong
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001982:Bronchial Diseases / Q000473:pathology / Q000628:therapy*; D020878:Device Removal; D004285:Dogs; D004867:Equipment Design; D005240:Feasibility Studies; D012137:Respiratory System / Q000473:pathology*; D012449:Safety; D015607:Stents / Q000009:adverse effects; D014135:Tracheal Stenosis / Q000473:pathology / Q000628:therapy*