Vascular reactivity and flow characteristics of radial artery and long saphenous vein coronary bypass grafts: a 5-year follow-up.
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.
Webb
Carolyn M
CM
Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College London, UK. c.webb@imperial.ac.uk
Moat
Neil E
NE
Chong
Chee F
CF
Collins
Peter
P
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
D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate; D000241:Adenosine