title: Stents covered by an autologous arterial graft in porcine coronary arteries: feasibility, vascular injury and effect on neointimal hyperplasia.
abstract: OBJECTIVE
  The use of stents has improved results after balloon coronary angioplasty. Several materials have been proposed for covering the metallic surface of the stent to reduce the rate of subacute thrombosis and restenosis. In our institution, an autologous arterial graft was used for covering the external surface of a conventional stent. The angiographic and histological response in a porcine coronary artery model was investigated.
  
  
  METHODS
  An autologous arterial graft was removed from the femoral artery and carefully prepared. Subsequently, a conventional stent was covered externally by the arterial graft. Twenty-two covered stents and 22 uncovered regular stents were implanted alternatively in the coronary arteries of 22 pigs. One animal died immediately after the procedure, due to thrombus formation in the uncovered stent. Six animals were sacrificed at seven days and the remaining animals were sacrificed at two months. Before the sacrifice, coronary angiography was performed in all animals.
  
  
  RESULTS
  Thrombosis was detected in two control segments and in one covered stented segment. After seven days, the luminal surface of the covered stents was covered by a new endothelial layer in contrast to partial endothelial cell appearance in the control group. The angiographic parameters were similar between the two groups. Histologically, the covered stents were associated with less vascular injury compared to uncovered stents. In covered stents a trend towards reduction of maximal intimal hyperplasia was detected (covered: 116.6 +/- 47.75 vs uncovered: 150.25 +/- 46.81 microns, p = 0.08); also the thickness of the arterial media was reduced (covered: 21.34 +/- 10.28 vs uncovered: 102.63 +/- 18.71 microns, p = 0.02). The luminal and vessel areas were similar in the two groups.
  
  
  CONCLUSIONS
  The preparation and implantation of the autologous arterial graft-covered stent is technically safe and feasible. This type of covered stent results in accelerated endothelialization, less vascular injury, thinning of the arterial media and a trend to reduce the intimal hyperplasia in normal coronary arteries.
authors.affiliation: Department of Cardiology, University of Athens, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Stefanadis
authors.forename: K
authors.initials: K
authors.lastname: Toutouzas
authors.forename: E
authors.initials: E
authors.lastname: Tsiamis
authors.forename: C
authors.initials: C
authors.lastname: Vlachopoulos
authors.forename: S
authors.initials: S
authors.lastname: Vaina
authors.forename: D
authors.initials: D
authors.lastname: Tsekoura
authors.forename: L
authors.initials: L
authors.lastname: Haldi
authors.forename: E
authors.initials: E
authors.lastname: Stefanadi
authors.forename: M
authors.initials: M
authors.lastname: Gravanis
authors.forename: P
authors.initials: P
authors.lastname: Toutouzas
mesh_terms: D000818:Animals; D017023:Coronary Angiography; D001026:Coronary Artery Bypass / Q000379:methods*; D003327:Coronary Disease / Q000473:pathology / Q000601:surgery*; D003331:Coronary Vessels / Q000648:ultrastructure; D005263:Femoral Artery / Q000637:transplantation*; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009389:Neovascularization, Pathologic; D015607:Stents; D013552:Swine; D014182:Transplantation, Autologous; D017539:Tunica Intima / Q000473:pathology / Q000648:ultrastructure