title: Late effects of low-energy gamma-emitting stents in a rabbit iliac artery model.
abstract: OBJECTIVE
  To determine the long-term dose response of novel low-dose gamma-emitting stents in a rabbit iliac artery model.
  
  
  METHODS
  Control stents (n=24) and 103Pd stents 1.0 to 4.0 mCi (n=36) were implanted in the iliac arteries of 30 New Zealand rabbits. Stents were evaluated by intravascular ultrasound (immediately post procedure and before killing) and by histomorphometry.
  
  
  RESULTS
  At 26 weeks, 28 rabbits were killed, with no evidence of stent thrombosis. In the body of the stent there was a dose-response relationship with 50% inhibition of intimal hyperplasia at the highest activity compared to control stents (p=0.07) and a significant increase in intimal hyperplasia at the lowest activity (p < 0.01). At the stent edges, there was a significant reduction of lumen area at all activity levels compared to control stents, which was most prominent at the proximal stent edge. Higher-activity stents demonstrated incomplete endothelialization and immature neointimal formation.
  
  
  CONCLUSIONS
  Continuous low-dose-rate irradiation by gamma-emitting 103Pd stents is feasible with reduction of in-stent hyperplasia in a dose-related manner. However, significant narrowing at the stent edges, increased in-stent hyperplasia at lower activities, and incomplete vascular healing with persistence of immature neointima at higher activities are significant limitations.
authors.affiliation: The Roy and Ann Foss Interventional Cardiology Research Program, Terrence Donnelly Heart Center, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. straussb@smh.toronto.on.ca
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Strauss
authors.forename: Chris
authors.initials: C
authors.lastname: Li
authors.forename: Heather A
authors.initials: HA
authors.lastname: Whittingham
authors.forename: Fermin O
authors.initials: FO
authors.lastname: Tio
authors.forename: Michael J B
authors.initials: MJ
authors.lastname: Kutryk
authors.forename: Christian
authors.initials: C
authors.lastname: Janicki
authors.forename: John D
authors.initials: JD
authors.lastname: Sparkes
authors.forename: Todd
authors.initials: T
authors.lastname: Turnlund
authors.forename: William L
authors.initials: WL
authors.lastname: Sweet
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000627:therapeutic use*; D006965:Hyperplasia / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D007083:Iliac Artery / Q000473:pathology / Q000528:radiation effects*; D023421:Models, Animal; D010165:Palladium / Q000627:therapeutic use*; D011817:Rabbits; D011853:Radiobiology; D011868:Radioisotopes / Q000627:therapeutic use*; D012008:Recurrence; D015607:Stents / Q000009:adverse effects; D017539:Tunica Intima / Q000473:pathology / Q000528:radiation effects*; D014654:Vascular Patency
chemical_list: D011868:Radioisotopes; D010165:Palladium