title: Tissue response to covered Wallstents.
abstract: OBJECTIVE
  To evaluate and compare the healing response related to two types of graft-covered Wallstents (WSs) and an uncovered WS in the canine iliac artery.
  
  
  METHODS
  Eight bare mesh WSs, 10 polyethylene terephthalate interbraided WSs (PET-WSs), and six polytetrafluoroethylene covered WSs (ePTFE-WSs) were placed in the iliac arteries of 12 dogs. Arteriograms were obtained before and after implantation and at explantation. Devices were explanted at 1 month (n = 8), 3 months (n = 6), and 6 months (n = 10) and sent for histologic study.
  
  
  RESULTS
  One ePTFE-covered stent-graft was found to be thrombosed at 3 months; the remaining 23 of 24 implants remained patent to the time of explantation. The WS and ePTFE-WS both generated a uniform myointimal cell response without inflammation. The PET-WS induced a fibrous luminal response with substantial foreign body-type inflammatory reaction around the PET fibers. Although neointima associated with the PET-WS appeared thicker than that associated with either the ePTFE-WS or the bare WS, none of the patent implants developed greater than 50% angiographic narrowing.
  
  
  CONCLUSIONS
  The PET-WS induced chronic inflammation, a response not seen with either the WS or ePTFE-WS. This may explain the occurrence of pain and/or fever in human studies of arterial PET endoluminal stent-grafts. Patency for all three implants was excellent in this model.
authors.affiliation: Department of Radiology, Cleveland Clinic Foundation, OH 44195, USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Dolmatch
authors.forename: Y H
authors.initials: YH
authors.lastname: Dong
authors.forename: S O
authors.initials: SO
authors.lastname: Trerotola
authors.forename: D W
authors.initials: DW
authors.lastname: Hunter
authors.forename: L H
authors.initials: LH
authors.lastname: Brennecke
authors.forename: R
authors.initials: R
authors.lastname: LaBounty
mesh_terms: D000818:Animals; D004285:Dogs; D005549:Foreign-Body Reaction / Q000209:etiology* / Q000473:pathology; D007083:Iliac Artery / Q000473:pathology; D011138:Polytetrafluoroethylene; D015607:Stents; D017539:Tunica Intima / Q000473:pathology; D014654:Vascular Patency / Q000502:physiology
chemical_list: D011138:Polytetrafluoroethylene