title: Vascular reactivity and flow characteristics of radial artery and long saphenous vein coronary bypass grafts: a 5-year follow-up.
abstract: BACKGROUND
  Radial artery (RA) aortocoronary bypass grafts anastomosed to a branch of the circumflex coronary artery have significantly better patency rates than saphenous vein (SV) grafts at 5 years, but the physiological characteristics and mechanisms involved are not clearly defined. We compared RA and SV graft vasomotor and flow responses to endothelium-dependent and -independent stimuli 5 years after surgery in a subgroup of patients enrolled in the Radial artery versus Saphenous Vein Patency (RSVP) trial.
  
  
  RESULTS
  Twenty-seven patients were included in the study (RA, n=15; SV, n=12). Graft blood flow was calculated from flow velocity, measured by intracoronary Doppler, and luminal diameter, measured by quantitative coronary angiography, before and after intragraft infusions of adenosine, acetylcholine, and isosorbide dinitrate. At rest, RA luminal diameters were significantly smaller than SV luminal diameters (P=0.029), blood flow velocity was greater in RA than SV (P=0.008), and volume blood flows were similar. RA but not SV dilated in response to adenosine and isosorbide dinitrate (all P<0.05, RA versus SV, percent change from baseline), and there were no significant differences in the diameter responses to acetylcholine. Volume blood flow responses to adenosine, acetylcholine, and isosorbide dinitrate were comparable.
  
  
  CONCLUSIONS
  Five years after surgery, RA coronary bypass conduits grafted to a single coronary territory demonstrated preserved flow-mediated vasodilatation, whereas SV grafts did not. Our results may provide insight into the more favorable patency of RA grafts over SV grafts.
  
  
  BACKGROUND
  http://www.clinicaltrials.gov. Unique identifier: NCT00139399.
authors: Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, UK. c.webb@imperial.ac.uk
authors: Carolyn M
authors: CM
authors: Webb
authors: Neil E
authors: NE
authors: Moat
authors: Chee F
authors: CF
authors: Chong
authors: Peter
authors: P
authors: Collins
mesh_terms: D000241:Adenosine; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D017023:Coronary Angiography; D001026:Coronary Artery Bypass / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000601:surgery*; D004730:Endothelium, Vascular / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D007548:Isosorbide Dinitrate; D017534:Radial Artery / Q000637:transplantation*; D012501:Saphenous Vein / Q000637:transplantation*; D013997:Time Factors; D018084:Ultrasonography, Interventional; D014654:Vascular Patency / Q000187:drug effects / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate; D000241:Adenosine