title: Evaluation of platelet deposition and neointimal hyperplasia of heparin-coated small-caliber ePTFE grafts in a canine femoral artery bypass model.
abstract: BACKGROUND
  Bypass graft failure due to acute thrombosis and intimal hyperplasia remains a major challenge in small-diameter vascular prosthetic graft reconstruction. Heparin has been shown to prevent thrombus formation and inhibit intimal antithrombotic in animal studies. In this study, we evaluated the effect of small-caliber heparin-coated expanded polytetrafluoroethylene (ePTFE) grafts on platelet deposition and intimal hyperplasia in a canine model of femoral artery bypass grafting.
  
  
  METHODS
  Nine adult greyhound dogs underwent placement of bilateral femorofemoral artery bypass grafts with ePTFE grafts (4 mm diameter and 7 cm long). In each animal, a heparin-coated ePTFE graft was placed on one side while a noncoated graft was placed on the contralateral side which served as the control. Platelet deposition was measured by autologous (111)indium-labeling and scintillation camera imaging analysis in 24 h. The graft patency was assessed at 4 weeks following the bypass. The effect of intimal hyperplasia was assessed with histological and morphometric analysis.
  
  
  RESULTS
  Platelet deposition on the heparin-coated grafts at 24 h was significantly reduced by 72% as compared to controls (P = 0.001). The patency rate was 44% in control grafts and 89% in heparin-coated grafts. There was a significant reduction of graft intimal hyperplasia at both proximal (0.38 +/- 0.21 mm(2)) and distal (0.19 +/- 0.06 mm(2)) anastomoses in the heparin-coated grafts as compared with proximal (1.01 +/- 0.28 mm(2)) and distal (0.42 +/- 0.01 mm(2)) anastomoses in the untreated control grafts, respectively (P < 0.05). Heparin coating significantly reduced graft neointimal hyperplasia at patent graft anastomoses by 55-72% as compared to controls.
  
  
  CONCLUSIONS
  These data demonstrate that heparin coating of ePTFE significantly reduced early platelet deposition and inhibited anastomotic neointimal hyperplasia. Moreover, small-caliber heparin-coated ePTFE graft significantly increased graft patency in a canine femoral artery bypass model. This may represent a promising treatment strategy for improving the clinical performance of small-caliber prosthetic vascular grafts.
authors.affiliation: Division of Vascular Surgery & Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Methodist Hospital, Houston, Texas 77030, USA.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Lin
authors.forename: Ruth L
authors.initials: RL
authors.lastname: Bush
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Alan B
authors.initials: AB
authors.lastname: Lumsden
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
mesh_terms: D000714:Anastomosis, Surgical; D000818:Animals; D000925:Anticoagulants; D001792:Blood Platelets / Q000473:pathology*; D001807:Blood Vessel Prosthesis; D020099:Coated Materials, Biocompatible; D004285:Dogs; D005263:Femoral Artery / Q000473:pathology / Q000601:surgery*; D006493:Heparin; D006965:Hyperplasia; D011138:Polytetrafluoroethylene; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*; D014654:Vascular Patency
chemical_list: D000925:Anticoagulants; D020099:Coated Materials, Biocompatible; D011138:Polytetrafluoroethylene; D006493:Heparin