title: A nitinol "U-Clip" versus sutured arteriovenous anastomosis: local tissue response and intimal hyperplasia development in a sheep model.
abstract: OBJECTIVE
  This study sought to compare the local tissue response and subsequent volume of intimal hyperplasia (IH) that develops throughout the maturation of an arteriovenous fistula created using continuous/interrupted polypropylene with that of a novel, metal-alloy, penetrating anastomotic clip device.
  
  
  METHODS
  Forty-six fistulae were created in 23 sheep under a paired design using the nitinol U-Clip (n = 23) in one hind limb and continuous (n = 20) or interrupted (n = 3) polypropylene suture for the other. Animals were killed at 4 (n = 3), 14 (n = 3), 28 (n = 10), 42 (n = 3), and 180 (n = 4) days. Histological sections were evaluated for quantitative histology and immunohistochemistry.
  
  
  RESULTS
  Compared with continuous polypropylene, U-Clip specimens demonstrated less intima-media area per unit length (IMA/L), proliferating cells, and tissue necrosis at all time points (MANOVA, F = 9.8-24.1, all p ≤ .005; observed power >82%). Specifically, values of IMA/L were reduced by 5% (p = .97), 37% (p = .02), 33% (p < .01), 9% (p = .42), and 14% (p = .22) at the time points of 4, 14, 28, 42, and 180 days respectively. Proliferating cells were reduced by 75% (p < .01), 72% (p = .03), 76% (p = .03), 27% (p = .31), and 60% (p = .01) and tissue necrosis by 67% (p < .01), 58% (p = .02), 40% (p = .33), 21% (p = .43), 77% (p = .11). In a 28-day comparison between U-Clip and interrupted polypropylene the U-Clip group demonstrated a 4% (p = .65) reduction in IMA/L, 74% (p < .01) in proliferating cells and 49% (p < .05) in tissue necrosis.
  
  
  CONCLUSIONS
  These results provide evidence of reduced local tissue necrosis, proliferating cells, and IH, favouring arteriovenous fistulae created using the U-Clip anastomotic device over conventional polypropylene suture techniques most evident over the first 4 weeks.
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia; The Vascular Institute, Prince of Wales Hospital, Sydney, Australia. Electronic address: r.varcoe@unsw.edu.au.
authors: R L
authors: RL
authors: Varcoe
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia.
authors: A B P
authors: AB
authors: Teo
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia.
authors: M H
authors: MH
authors: Pelletier
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia.
authors: Y
authors: Y
authors: Yu
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia; Adult Cancer Program, Lowy Cancer Research Centre, Faculty of Medicine, University of New South Wales, Sydney, Australia.
authors: J L
authors: JL
authors: Yang
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia.
authors: P J
authors: PJ
authors: Crowe
authors: Department of Surgery, Prince of Wales Hospital, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, Faculty of Medicine, Sydney, Australia; The University of New South Wales, Sydney, Australia.
authors: W R
authors: WR
authors: Walsh
mesh_terms: D000497:Alloys; D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D049109:Cell Proliferation; D004867:Equipment Design; D005263:Femoral Artery / Q000473:pathology / Q000601:surgery*; D005268:Femoral Vein / Q000473:pathology / Q000601:surgery*; D006614:Hindlimb; D006965:Hyperplasia; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000098:blood supply*; D009336:Necrosis; D058426:Neointima; D011126:Polypropylenes; D012756:Sheep; D013525:Surgical Instruments; D013536:Suture Techniques / Q000009:adverse effects / Q000295:instrumentation; D013537:Sutures; D013997:Time Factors
chemical_list: D000497:Alloys; D011126:Polypropylenes; C013616:nitinol
keywords: Arteriovenous fistula; Haemodialysis vascular access; Intimal hyperplasia; Vascular anastomotic clip