title: Effect of antithrombotic agents on the patency of PTFE-covered stents in the inferior vena cava: an experimental study.
abstract: OBJECTIVE
  To evaluate the efficacy of antithrombotic agents in the prevention of stenosis of polytetrafluoroethylene (PTFE)-covered stents in the venous system.
  
  
  METHODS
  Spiral Z stents covered with PTFE (PTFE-covered stents) were placed in the inferior vena cava (IVC) of 34 dogs. Nineteen dogs, used as a control group, were sacrificed at 2, 4, and 12 weeks. Fifteen dogs, previously given antithrombotic agents [cilostazol (n = 5), warfarin potassium (n = 5), cilostazol plus warfarin potassium (n = 5)] were sacrificed at 4 weeks, and then examined angiographically and histopathologically. The effect of the antithrombotic agents was compared between groups.
  
  
  RESULTS
  The patency rate of the antithrombotic agent group was 93% (14/15), which was higher than the control group rate of 63% (12/19). The mean stenosis rate of the patent stent at both ends and at the midportion was lower at 4 weeks in the antithrombotic agent group than in the control group. In particular, the mean stenosis rate in the cilostazol plus warfarin potassium group was significantly lower than the control group (Tukey's test, p < 0.05). The mean neointimal thickness of the patent stent at both ends and at the midportion was thinner at 4 weeks in the antithrombotic agent group than in the control group. In particular, the thickness of the neointima in the cilostazol plus warfarin potassium group was significantly decreased when compared with the control group (Tukey's test p < 0.05). At 4 weeks, endothelialization in the antithrombotic agent group tended to be almost identical to that in the control group.
  
  
  CONCLUSIONS
  The present study suggests that administration of an antithrombotic agent is an effective way of preventing the stenosis induced by a neointimal thickening of PTFE-covered stents in the venous system.
authors.affiliation: Department of Radiology, Nara Medical University, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Makutani
authors.forename: K
authors.initials: K
authors.lastname: Kichikawa
authors.forename: H
authors.initials: H
authors.lastname: Uchida
authors.forename: M
authors.initials: M
authors.lastname: Maeda
authors.forename: N
authors.initials: N
authors.lastname: Konishi
authors.forename: Y
authors.initials: Y
authors.lastname: Hiasa
authors.forename: T
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
mesh_terms: D000818:Animals; D000077407:Cilostazol; D004285:Dogs; D004730:Endothelium, Vascular / Q000473:pathology; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D011138:Polytetrafluoroethylene; D015607:Stents; D013777:Tetrazoles / Q000494:pharmacology; D017539:Tunica Intima / Q000473:pathology; D014682:Vena Cava, Inferior; D014859:Warfarin / Q000494:pharmacology
chemical_list: D005343:Fibrinolytic Agents; D013777:Tetrazoles; D014859:Warfarin; D011138:Polytetrafluoroethylene; D000077407:Cilostazol