Relation of preoperative radial artery flow-mediated dilatation to nitric oxide bioavailability in radial artery grafts used in off-pump coronary artery bypass grafting.
The radial artery is prone to vasospasm after coronary bypass surgery, and endothelial dysfunction is likely to be a key factor. We investigated whether endothelial dysfunction in radial artery conduits is present, and can be identified, preoperatively using a simple noninvasive ultrasound test of radial artery endothelial response, flow-mediated dilatation (FMD). The study population consisted of 126 patients scheduled for coronary artery bypass grafting. The afternoon before operation, patients had noninvasive ultrasound assessment of endothelial function in the left radial artery by FMD, which measures change in arterial size after an increase in flow-an endothelial-dependent response. Surplus graft segments were obtained at operation and nitric oxide bioavailability within the vessels determined from ex vivo responses to acetylcholine. Preoperative FMD in the radial artery was associated with vasorelaxations to acetylcholine in radial artery grafts (p<0.001 for both dose-response curves and maximum relaxations), although there was weak borderline association between FMD and vasorelaxations of saphenous vein grafts (p=0.07 for dose-response curves and p<0.05 for maximum relaxations). In multivariate analysis including cardiac risk factors, FMD was a predictor of vasorelaxations of radial artery grafts (beta=0.020, SE=0.009, p=0.030), independent of classic risk factors for atherosclerosis. In conclusion, there is significant interindividual variation in the endothelial function of vessels used for coronary artery bypass surgery, particularly the radial artery. These differences are present and can be identified preoperatively by FMD.
Antoniades
Charalambos
C
Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom. antoniad@well.ox.ac.uk
Mussa
Shafi
S
Shirodaria
Cheerag
C
Lee
Justin
J
Diesch
Jonathan
J
Taggart
David P
DP
Channon
Keith M
KM
Leeson
Paul
P
D000368:Aged; D001682:Biological Availability; D047549:Coronary Artery Bypass, Off-Pump; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009569:Nitric Oxide / Q000096:biosynthesis*; D017534:Radial Artery / Q000378:metabolism / Q000503:physiopathology* / Q000637:transplantation*; D012307:Risk Factors; D014661:Vasoconstriction / Q000502:physiology
D009569:Nitric Oxide