title: Healing of implanted expanded polytetrafluoroethylene vascular access grafts with different internodal distances: a histologic study in dogs.
abstract: OBJECTIVE
  We assessed characteristics of healing, over time, of two types of expanded polytetrafluoroethylene grafts.
  
  
  METHODS
  An experimental histological study in dogs.
  
  
  METHODS
  The graft types studied had the same internal diameter (5 mm) but different internodal distances. In one, the internodal distance was 60 microm in the external surface and 20 microm in the luminal surface. In the other, the internodal distance was 30 microm throughout the material. Sixteen grafts of each type were implanted between the femoral artery and vein in 16 dogs; explanted 1, 2, 4 or 12 weeks later; and examined histologically.
  
  
  RESULTS
  In both graft types, infiltrating-cell density and maximum cell-penetration depth increased significantly between 1 and 2 weeks after implantation, but no significant increases occurred after 2 weeks. The number of inflammatory cells peaked 1 week after implantation and decreased significantly by 2 weeks. Subsequently, there were no significant changes in inflammatory cell numbers, suggesting that the inflammatory phase was over by 2 weeks after implantation and the grafts had become attached to surrounding tissue. There were no significant differences between the two graft types in cell density, cell-penetration depth, or number of inflammatory cells at any assessment time.
  
  
  CONCLUSIONS
  Our results provide histologic support for guidelines recommending that synthetic vascular grafts for hemodialysis access should not be cannulated until 2 weeks after implantation. Since increasing the internodal distance to 60 microm in the external surface had no effect on graft healing, methods other than manipulation of internodal distance should be used in developing a graft suitable for early cannulation.
authors.affiliation: Division of Vascular Surgery, Department of Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Kuzuya
authors.forename: M
authors.initials: M
authors.lastname: Matsushita
authors.forename: K
authors.initials: K
authors.lastname: Oda
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: N
authors.initials: N
authors.lastname: Nishikimi
authors.forename: T
authors.initials: T
authors.lastname: Sakurai
authors.forename: K
authors.initials: K
authors.lastname: Komori
mesh_terms: D000818:Animals; D019917:Blood Vessel Prosthesis Implantation; D002465:Cell Movement / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D004285:Dogs; D005260:Female; D005263:Femoral Artery / Q000166:cytology / Q000187:drug effects / Q000601:surgery; D005268:Femoral Vein / Q000166:cytology / Q000187:drug effects / Q000601:surgery; D008297:Male; D023421:Models, Animal; D008955:Models, Cardiovascular; D011138:Polytetrafluoroethylene / Q000494:pharmacology*; D019736:Prostheses and Implants; D013997:Time Factors; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D020099:Coated Materials, Biocompatible; D011138:Polytetrafluoroethylene