title: Dose-response effects of 32P radioactive stents in an atherosclerotic porcine coronary model.
abstract: BACKGROUND
  Experimental studies have demonstrated that 32P radioactive stents reduce neointimal formation at 28 days in porcine iliac and coronary arteries. Our objective was to determine the long-term dose-response effects of 1.0- to 12.0-microCi 32P radioactive stents in a porcine atherosclerotic coronary model.
  
  
  RESULTS
  Control (n=19) and 1.0- to 12.0-microCi 32P radioactive (n=43) stents (total, n=62) were implanted in the coronary arteries of 31 miniature swine at 28 days after creation of a fibrocellular plaque by overstretch balloon injury and cholesterol feeding. Angiography and histomorphometry were performed at 6 months. Stent thrombosis occurred in 3 radioactive (7.7%) and no control stents (P=0.54). On histology, the mean neointimal area and the percent in-stent stenosis correlated positively with increasing stent activity (r=0.64, P<0.001). The mean neointimal area (mm2) for the stents with >/=3.0 microCi 32P (3.57+/-1.21) was significantly greater than that for the nonradioactive stents (1.78+/-0.68, P<0.0001). The neointima of the stents with >/=3.0 microCi 32P was composed of smooth muscle cells, matrix proteoglycans, calcification, foam cells, and cholesterol clefts.
  
  
  CONCLUSIONS
  Continuous low-dose-rate irradiation delivered by high-activity (32)P radioactive stents promotes the formation of an "atheromatous" neointima after 6 months in this experimental model. These data may be useful for predicting late tissue responses to radioactive stents in human coronary arteries.
authors.affiliation: Cardiology Research Foundation, Washington Hospital Center, Walter Reed Army Medical Center, Washington, DC 20100, USA. ajc2@mhg.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Carter
authors.forename: D
authors.initials: D
authors.lastname: Scott
authors.forename: L
authors.initials: L
authors.lastname: Bailey
authors.forename: T
authors.initials: T
authors.lastname: Hoopes
authors.forename: R
authors.initials: R
authors.lastname: Jones
authors.forename: R
authors.initials: R
authors.lastname: Virmani
mesh_terms: D000818:Animals; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000628:therapy*; D003328:Coronary Thrombosis / Q000209:etiology; D003331:Coronary Vessels / Q000473:pathology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D009131:Muscle, Smooth, Vascular / Q000000981:diagnostic imaging* / Q000473:pathology; D010761:Phosphorus Radioisotopes / Q000627:therapeutic use*; D015607:Stents / Q000009:adverse effects; D013552:Swine; D013556:Swine, Miniature
chemical_list: D010761:Phosphorus Radioisotopes