title: Biologic fixation of polyester- versus polyurethane-covered stents in a porcine model.
abstract: OBJECTIVE
  Migration of endoprostheses remains a concern in endovascular aneurysm treatment. Biologic fixation is supposed to enhance anchorage, but the diseased atherosclerotic aorta in humans has demonstrated a limited capacity to incorporate an endoprosthesis by cellular proliferation. The biologic response of two different types of endoprostheses was evaluated in the porcine aorta.
  
  
  METHODS
  Two types of endoprostheses--four polyurethane-covered (PUC) stents with a macroporous polyurethane covering and four polyester-covered (PEC) stents with a woven polyester covering--were implanted in eight infrarenal porcine aortas for 6 weeks. Electron microscopy and qualitative and quantitative microscopy were performed on serial cross sections.
  
  
  RESULTS
  The PUC stents demonstrated an increase in diameter (from 8 mm +/- 1 to 10 mm +/- 1, 12.5%; P = .009), whereas the PEC stents persisted in their original dimensions (8 mm +/- 1, 0%). PUC and PEC stents were covered by continuous thrombus-free neointima (269 microm +/- 51 vs 575 microm +/- 113, respectively; P < .01). The PUC stents demonstrated firm attachment to the aorta as a consequence of a granulation tissue with ingrowth into the pores of the polyurethane covering. The PEC stents remained in loose contact with the aorta in the absence of tissue ingrowth.
  
  
  CONCLUSIONS
  Enhanced biologic fixation was achieved by extensive granulation tissue invading the pores of PUC endoprostheses. This finding can modify the design of future devices.
authors.affiliation: Department of Cardiovascular Surgery, University Hospital, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland. bettina.marty@chuv.hospvd.ch
authors.forename: Bettina
authors.initials: B
authors.lastname: Marty
authors.forename: Anders J
authors.initials: AJ
authors.lastname: Leu
authors.forename: Antonio
authors.initials: A
authors.lastname: Mucciolo
authors.forename: Ludwig Karl
authors.initials: LK
authors.lastname: von Segesser
mesh_terms: D000818:Animals; D001011:Aorta / Q000033:anatomy & histology / Q000601:surgery* / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000648:ultrastructure; D008854:Microscopy, Electron; D023421:Models, Animal; D011091:Polyesters; D011140:Polyurethanes; D015607:Stents; D013552:Swine
chemical_list: D011091:Polyesters; D011140:Polyurethanes