title: Optimal covering material for stent-grafts placed in the portal vein in a canine model.
abstract: OBJECTIVE
  We evaluated the suitability of Dacron, polytetrafluoroethylene (PTFE), and small intestinal submucosa (SIS) as a covering material for stent-grafts placed in the portal vein as compared with a bare stent.
  
  
  METHODS
  Using 24 beagle dogs, either bare stents or stent-grafts covered with Dacron, PTFE, or SIS were placed in the main trunk of the portal vein in 6 animals each. Portography was performed immediately after stent placement, and at 2, 4, and 12 weeks thereafter. Next, the extracted stents or stent-grafts were examined histopathologically. Neointimal thickness adjacent to the stent wire and at the midportion between the stent wires was compared among the groups. Then, the neointimal thickness at the sub- and supragraft sites was compared between each stent-graft group. Serial changes in the histologic features of the thickened neointima were also investigated.
  
  
  RESULTS
  No significant difference was noted in the mean stenotic ratio of the portal vein diameter between the bare stent and PTFE groups, whereas it was significantly higher in the Dacron and SIS groups compared with the bare stent group. In neither of the studies on neointimal thickness adjacent to the stent wire and at the midportion between the stent wires were any significant differences noted between the neointimal thickness of the bare stent group and the sum of the neointimal thickness of the PTFE group, whereas the sum of the neointimal thickness of the Dacron and SIS groups was significantly greater than that of the bare stent group at both sites. In the comparison of the supragraft neointimal thickness, the SIS group showed significantly greater thickness than the PTFE group, while the difference between the Dacron and PTFE groups was not significant. In the comparison of the subgraft neointimal thickness, the Dacron and SIS groups showed significantly greater thickness than the PTFE group.
  
  
  CONCLUSIONS
  The present results indicate that of the three covering materials examined here, PTFE is the most suitable material for grafts placed in the portal vein.
authors.affiliation: Department of Radiology, Wakayama Medical University, 811-1, Kimiidera, Wakayama Shi, Wakayama 641-8510, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Ishii
authors.forename: Morio
authors.initials: M
authors.lastname: Sato
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Sonomura
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Yamada
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Tanihata
authors.forename: Hime
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Terada
authors.forename: Shinya
authors.initials: S
authors.lastname: Sahara
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawai
authors.forename: Masashi
authors.initials: M
authors.lastname: Kimura
authors.forename: Ichiro
authors.initials: I
authors.lastname: Mori
mesh_terms: D000818:Animals; D019917:Blood Vessel Prosthesis Implantation; D049109:Cell Proliferation / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D004195:Disease Models, Animal; D004285:Dogs; D042783:Endothelial Cells / Q000187:drug effects / Q000473:pathology; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000209:etiology; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000473:pathology; D011093:Polyethylene Terephthalates / Q000494:pharmacology; D011138:Polytetrafluoroethylene / Q000494:pharmacology; D011169:Portal Vein / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011172:Portography; D015607:Stents; D013997:Time Factors; D017539:Tunica Intima / Q000166:cytology / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D020099:Coated Materials, Biocompatible; D011093:Polyethylene Terephthalates; D011138:Polytetrafluoroethylene