Background: 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 4% of patients. The aim of this study was to analyze the vasoreactive properties of the radial artery and to compare them with those of the internal mammary and the gastroepiploic arteries.
Methods and results: Human radial (56 from 15 patients), internal mammary (77 from 20 patients), and gastroepiploic (41 from 12 patients) artery ring segments were mounted on a strain gauge in oxygenated, normothermic Krebs' solution at optimal resting tension. With KCl (100 mM) serving as the control, the dose-response curves to norepinephrine, serotonin, and thromboxane A2 mimetic were obtained, permitting assessment of force of contraction and sensitivity. Functional endothelium was assessed with acetylcholine. Smooth muscle-dependent relaxation was assessed with sodium nitroprusside. The radial artery had stronger contractions to KCl 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 three vessels had equal sensitivities to norepinephrine and serotonin. The gastroepiploic artery had a lower sensitivity to thromboxane A2 mimetic than the two other vessels.
Conclusions: 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.