title: Ionizing radiation to prevent arterial intimal hyperplasia at the edges of the stent: induces necrosis and fibrosis.
abstract: BACKGROUND
  Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries in multicenter clinical trials, information is lacking on how irradiation affects arterial histology after stenting and especially how it affects the edges of the stent. We investigated intimal hyperplasia recasting with histological changes in arterial wall at the edges of the stent after arterial stenting followed by adequate external radiation for the prevention of intimal hyperplasia in pigs.
  
  
  METHODS
  The aorta was experimentally stented in 30 pigs who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies 6 weeks after procedure.
  
  
  RESULTS
  Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control pigs. In the irradiated group histological examination at the edges of the stent showed thin neointimal proliferation with an intact endothelium. In all sections analyzed in the 20-Gy irradiated group the vascular media at 45 days contained necrotic areas and fibrosis with calcifications.
  
  
  CONCLUSIONS
  After arterial injury, adequate ionizing radiation effectively reduces neointimal thickening. Irradiation-induced histological changes include previously undetected recasting with necrosis and fibrosis at the arterial edges of the stent. The parietal recasting we observed in animal arteries irradiated at high doses is unclear and a cause of concern especially after clinical spontaneous dissection was recently reported. The use of ionizing radiation for the prevention of arterial restenosis awaits confirmation with a long-term follow-up including specific experimental histological analyses.
authors.affiliation: Unit of Vascular Surgery, Tripode-Pellegrin Hospital, Bordeaux, France. eric.ducasse@chu-bordeaux.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Ducasse
authors.forename: Jacques
authors.initials: J
authors.lastname: Chevalier
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Cosset
authors.forename: Colette
authors.initials: C
authors.lastname: Creusy
authors.forename: François
authors.initials: F
authors.lastname: Eschwege
authors.forename: Francesco
authors.initials: F
authors.lastname: Speziale
authors.forename: Enrico
authors.initials: E
authors.lastname: Sbarigia
authors.forename: Dominique
authors.initials: D
authors.lastname: Midy
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baste
authors.forename: Eric
authors.initials: E
authors.lastname: Lartigau
mesh_terms: D000818:Animals; D001158:Arteries / Q000473:pathology* / Q000528:radiation effects*; D005260:Female; D006965:Hyperplasia / Q000517:prevention & control / Q000532:radiotherapy; D007150:Immunohistochemistry; D011839:Radiation, Ionizing; D018709:Statistics, Nonparametric; D015607:Stents / Q000009:adverse effects*; D034421:Sus scrofa