title: [A novel hirudin coating of vascular endoprostheses: experimental results].
abstract: OBJECTIVE
  Does hirudin coating improve the patency of iliac artery endoprostheses in comparison to non-hirudin-coated endoprostheses?
  
  
  METHODS
  Nitinol stents and stentgrafts covered with polytetrafluoroethylene (PTFE) were coated with the polymer polyamino-p-xylylene-co-poly-p-xylylene using chemical vapor deposition (CVD) technique. Hirudin was covalently bound to the surface of the endoprostheses via the amino-group. External factors (mounting of the prosthesis, sterilization, storage time and temperature, release) affecting the hirudin activity were evaluated in vitro. Five types of prostheses were compared in vivo: (1) plain and (2) CVD- and hirudin-coated stents; (3) plain, (4) CVD-coated, and (5) CVD- and hirudin-coated PTFE-stentgrafts. In 20 sheep, 16 protheses of each type were inserted in arteries pretreated with a Fogarty maneuver. The animals were followed for either 1 (n = 10) or 6 (n = 10) months. Immediately after implantation and after 1, 3, and 6 months, intravascular ultrasound (IVUS) and angiography were performed. The vascular specimens were analyzed histologically.
  
  
  RESULTS
  Within 10 weeks, the hirudin activity of coated stents dropped 60 % due to external factors; the activity of coated PTFE stentgrafts dropped 20 %. After 1, 3, and 6 months, IVUS and histology revealed a significantly reduced patency of the hirudin-coated stentgrafts compared to the other prostheses. Only IVUS showed a significantly reduced patency of hirudin coated stents after 1 and 3 months compared to plain and CVD-coated PTFE-stentgrafts. The reduced patency was caused by neointimal hyperplasia.
  
  
  CONCLUSIONS
  In an experimental setting, hirudin coating did not improve the patency of vascular endoprostheses.
authors.affiliation: Klinik für Radiologische Diagnostik, Universitätsklinikum der RWTH Aachen. schuerm@rad.rwth-aachen.de
authors.forename: K
authors.initials: K
authors.lastname: Schürmann
authors.forename: A
authors.initials: A
authors.lastname: Roos
authors.forename: J
authors.initials: J
authors.lastname: Meyer
authors.forename: B
authors.initials: B
authors.lastname: Ries
authors.forename: J
authors.initials: J
authors.lastname: Lahann
authors.forename: B
authors.initials: B
authors.lastname: Hermanns
authors.forename: A
authors.initials: A
authors.lastname: Kulisch
authors.forename: D
authors.initials: D
authors.lastname: Vorwerk
authors.forename: D
authors.initials: D
authors.lastname: Klee
authors.forename: R W
authors.initials: RW
authors.lastname: Günther
mesh_terms: D000792:Angiography; D000818:Animals; D001807:Blood Vessel Prosthesis; D020099:Coated Materials, Biocompatible; D005500:Follow-Up Studies; D006629:Hirudins; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design; D012756:Sheep; D015607:Stents; D018084:Ultrasonography, Interventional; D014654:Vascular Patency / Q000502:physiology
chemical_list: D020099:Coated Materials, Biocompatible; D006629:Hirudins; D011138:Polytetrafluoroethylene