title: A bioabsorbable (polyglactin), nonrestrictive, external sheath inhibits porcine saphenous vein graft thickening.
abstract: OBJECTIVE
  External, nonrestrictive, macro-porous polyester stents prevent neointima formation in porcine vein grafts and have been proposed as a therapeutic approach to the prevention of late vein graft failure. These stents are nonbiodegradable and therefore may promote long-term foreign body problems including infection and inflammation. The effect of external macro-porous biodegradable (polyglactin) sheaths on neointimal and medial thickening in porcine vein grafts was therefore investigated.
  
  
  METHODS
  Bilateral saphenous vein-carotid artery interposition grafting was performed in white Landrace pigs (n = 8) with external placement of polyglactin (Vicryl) sheaths (8 mm in diameter) on 1 side, with the contralateral side acting as a control. One month after surgery, grafts were explanted and wall dimensions measured on histological sections using computer-aided planimetry, and an immunocytochemical appraisal was carried out.
  
  
  RESULTS
  All grafts were patent at explantation. Polyglactin sheaths significantly reduced intimal thickness, medial thickness, and the percentage of proliferating cells compared with unsheathed controls. There was a pronounced accumulation of macrophages, giant cells, endothelial cells, and microvessels within and surrounding the biodegradable sheath compared with controls.
  
  
  CONCLUSIONS
  A nonrestrictive, biodegradable (polyglactin), external sheath reduces medial and intimal thickening in experimental saphenous vein grafts, possibly through inflammatory cell-mediated angiogenesis. If subsequent long-term studies confirm preservation of this beneficial effect, once the sheath biodegrades, this approach may have an advantage over the permanent polyester stent when applied clinically.
authors.affiliation: The Bristol Heart Institute, Bristol Royal Infirmary, University of Bristol, Bristol, UK. j.y.jeremy@bris.ac.uk
authors.forename: Jamie Y
authors.initials: JY
authors.lastname: Jeremy
authors.forename: Richard
authors.initials: R
authors.lastname: Bulbulia
authors.forename: Jason L
authors.initials: JL
authors.lastname: Johnson
authors.forename: Patricia
authors.initials: P
authors.lastname: Gadsdon
authors.forename: Vikram
authors.initials: V
authors.lastname: Vijayan
authors.forename: Nilima
authors.initials: N
authors.lastname: Shukla
authors.forename: Frank C T
authors.initials: FC
authors.lastname: Smith
authors.forename: Gianni D
authors.initials: GD
authors.lastname: Angelini
mesh_terms: D000704:Analysis of Variance; D000714:Anastomosis, Surgical / Q000379:methods; D000818:Animals; D001672:Biocompatible Materials; D002339:Carotid Arteries / Q000601:surgery*; D004195:Disease Models, Animal; D005260:Female; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D007150:Immunohistochemistry; D008297:Male; D018919:Neovascularization, Physiologic; D011098:Polyglactin 910; D011336:Probability; D012501:Saphenous Vein / Q000637:transplantation*; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D015607:Stents; D013499:Surface Properties; D013552:Swine; D017539:Tunica Intima / Q000473:pathology*; D017540:Tunica Media / Q000473:pathology*
chemical_list: D001672:Biocompatible Materials; D011098:Polyglactin 910