title: The effect of nonporous PTFE-covered stents on intimal hyperplasia following balloon arterial injury in minipigs.
abstract: OBJECTIVE
  To report an experimental study investigating the ability of nonporous polytetrafluoroethylene (PTFE) covering on a metallic stent to retard the development of neointimal hyperplasia (NIH).
  
  
  METHODS
  Three groups of Hanford miniature swine underwent standardized balloon injury to both external iliac arteries. Group I animals (control) received balloon injuries only. Group II had the site of balloon injury supported by a properly sized, balloon-expandable Palmaz stent placed directly over the injury site. Group III animals received a Palmaz stent covered with PTFE graft. All animals underwent arteriography immediately after intervention and again prior to sacrifice and specimen harvest at 4 weeks. The specimens were examined grossly and histologically at the proximal, middle, and distal segments for NIH development.
  
  
  RESULTS
  Uncovered stents developed significantly more NIH (p < 0.0001) and greater luminal narrowing (p < 0.001) than the controls. PTFE-covered stents (group III) exhibited less NIH (p < 0.001) and luminal reduction (p < 0.01) than bare stents (group II) at the middle portion of the stent-graft, but the PTFE cover had no effect on NIH and lumen reduction at the proximal or distal ends of the prosthesis.
  
  
  CONCLUSIONS
  PTFE-covered stents retarded NIH at 4 weeks, but only at the midportion of the devices; the covering did not prevent neointimal pannus ingrowth at the proximal and distal ends.
authors.affiliation: Department of Surgery, Montefiore Medical Center, The University Hospital for the Albert Einstein College of Medicine, New York, New York 10467, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Yuan
authors.forename: T
authors.initials: T
authors.lastname: Ohki
authors.forename: M L
authors.initials: ML
authors.lastname: Marin
authors.forename: R T
authors.initials: RT
authors.lastname: Quintos
authors.forename: D L
authors.initials: DL
authors.lastname: Krohn
authors.forename: J J
authors.initials: JJ
authors.lastname: Beitler
authors.forename: F J
authors.initials: FJ
authors.lastname: Veith
mesh_terms: D000792:Angiography; D000818:Animals; D002404:Catheterization / Q000009:adverse effects*; D002455:Cell Division; D006965:Hyperplasia; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D011138:Polytetrafluoroethylene; D015607:Stents; D013552:Swine; D013556:Swine, Miniature; D017539:Tunica Intima / Q000473:pathology*
chemical_list: D011138:Polytetrafluoroethylene