[Comparative vasoreactivity of the radial, internal mammary and gastroepiploic arteries. Implications in coronary...

Recently, satisfactory results were obtained in a series of patients in whom the radial artery was used as a conduit for coronary artery bypass. However, spasm of this conduit was observed in four percent of patients. The aim of this study was to analyze the vasoreactive properties of the radial artery and to compare them to those of the internal mammary and the gastroepiploic arteries. Human radial (56 from n = 15 patients), internal mammary (77 from n = 20 patients) and gastroepiploic (41 from n = 12 patients) arteries ring segments were mounted on a strain gauge in oxygenated, normothermic, Krebs solution at optimal resting tension. With potassium chloride (100 mM) serving as the control, the dose response curves to norepinephrine, serotonin and thromboxane A2 mimetic were obtained, hence permitting to assess force of contraction and sensitivity. Functional endothelium was assessed by acetylcholine. Smooth muscle-dependent relaxation was assessed by sodium nitroprusside. The radial artery had stronger contractions to potassium chloride than the other vessels. The radial and the gastroepiploic arteries with endothelium presented a higher contraction force than the internal mammary artery in response to norepinephrine and serotonin. The gastroepiploic artery had a lower sensitivity to thromboxane A2 mimetic compared to the two other vessels. This increased reactivity of the radial artery explains its propensity to spasm and emphasizes the need for antispastic drugs and platelet inhibitors when the radial artery is used for coronary artery bypass.