title: Prevention of neointimal hyperplasia associated with modified stretch expanded polytetrafluoroethylene hemodialysis grafts (Gore) in an experimental preclinical study in swine.
abstract: OBJECTIVE
  Stenosis is the main cause of hemodialysis vascular graft failure and it is primarily caused by neointimal hyperplasia (NH) development at the vein-graft anastomosis. Even though NH development factors are well known, their activation pathway still remains disputed and the real role of the mismatch compliance between the vein and the graft wall has not yet been resolved. The purpose of this experimental study in swine was to verify the possibility of preventing the development of NH at the vein-graft anastomosis using a modified commercially available longitudinal stretch expanded polytetrafluoroethylene (ePTFE) Gore (W. L. Gore & Associates, Flagstaff, Ariz) graft (either standard or heparin-bonded) with an added handmade ePTFE radial stretch cuff at one end to reduce the compliance between the graft and the vein wall.
  
  
  METHODS
  Twelve ePTFE stretch grafts (6 modified and 6 unmodified) were surgically placed as arterovenous grafts (AVGs) between the carotid artery and the external jugular vein in 6 pigs. In each pig, one modified graft was placed on one side and one corresponding unmodified graft on the other side as a control. In 4 pigs, standard stretch ePTFE Gore grafts were used, and in 2 pigs, heparin-bonded stretch Gore grafts were used; 2 pigs were also treated with antiplatelet drugs. All the implanted grafts had a total length of 8 cm and a diameter of 6 mm. The modified graft was realized by cutting a short segment of the commercially available graft lengthwise which was then sewn crosswise (rotated 90°) with the same diameter as the original graft and was then added to it. A Doppler ultrasound scan was used for monitoring the graft patency immediately, weekly, and before death. At death (21-28 days after implantation), artery, vein, and graft specimens were collected "en bloc" for histopathology.
  
  
  RESULTS
  The modified grafts in the antiplatelet-treated animals were able to completely prevent NH development on vein wall (100% in 2 subjects) which was also reduced in antiplatelet untreated animals (66.5%, 96.4%, and 100% in 3 subjects, respectively). The modified standard stretch grafts and similarly modified heparin-bonded stretch grafts obtained the same good results in NH prevention.
  
  
  CONCLUSIONS
  Data provide evidence of the efficacy of modified stretch ePTFE grafts with an added radial stretch cuff for the prevention of NH in swine models and support the hypothesis of the pivotal role of mismatch compliance between the graft and the vein wall in NH development.
authors.affiliation: Vascular and Endovascular Surgery Unit, Infermi Hospital, Rimini, Italy. maxgessaroli53@libero.it
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Gessaroli
authors.forename: Cristiano
authors.initials: C
authors.lastname: Bombardi
authors.forename: Massimo
authors.initials: M
authors.lastname: Giunti
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bacci
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects / Q000295:instrumentation*; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D002339:Carotid Arteries / Q000601:surgery*; D003187:Compliance; D003251:Constriction, Pathologic; D005260:Female; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D006965:Hyperplasia; D007601:Jugular Veins / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008422:Materials Testing; D023421:Models, Animal; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design; D006435:Renal Dialysis; D013552:Swine; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*; D018608:Ultrasonography, Doppler; D014654:Vascular Patency
chemical_list: D010975:Platelet Aggregation Inhibitors; D011138:Polytetrafluoroethylene