title: First-generation aortic endografts: analysis of explanted Stentor devices from the EUROSTAR Registry.
abstract: OBJECTIVE
  To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.
  
  
  METHODS
  The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.
  
  
  RESULTS
  Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.
  
  
  CONCLUSIONS
  Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.
authors.affiliation: Department of Surgery, Laval University, and Québec Biomaterials Institute, CHUQ, Québec City, Canada. robert.guidoin@crsfa.ulaval.ca
authors.forename: R
authors.initials: R
authors.lastname: Guidoin
authors.forename: Y
authors.initials: Y
authors.lastname: Marois
authors.forename: Y
authors.initials: Y
authors.lastname: Douville
authors.forename: M W
authors.initials: MW
authors.lastname: King
authors.forename: M
authors.initials: M
authors.lastname: Castonguay
authors.forename: A
authors.initials: A
authors.lastname: Traoré
authors.forename: M
authors.initials: M
authors.lastname: Formichi
authors.forename: L E
authors.initials: LE
authors.lastname: Staxrud
authors.forename: L
authors.initials: L
authors.lastname: Norgren
authors.forename: P
authors.initials: P
authors.lastname: Bergeron
authors.forename: J P
authors.initials: JP
authors.lastname: Becquemin
authors.forename: J M
authors.initials: JM
authors.lastname: Egana
authors.forename: P L
authors.initials: PL
authors.lastname: Harris
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys / Q000737:chemistry; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D001672:Biocompatible Materials / Q000737:chemistry; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D006801:Humans; D008297:Male; D011091:Polyesters / Q000737:chemistry; D011475:Prosthesis Failure; D011859:Radiography; D015607:Stents
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D011091:Polyesters; C013616:nitinol