VASOREACTIVITY OF THE RADIAL ARTERY - COMPARISON WITH THE INTERNAL MAMMARY AND GASTROEPIPLOIC ARTERIES WITH IMPLICATIONS FOR CORONARY-ARTERY SURGERY

Background. Recently, satisfactory results were obtained in a series o f patients in whom the radial artery was used as a conduit for coronar y artery bypass. However, spasm of this conduit was observed in 4% of patients. The aim of this study was to analyze the vasoreactive proper ties of the radial artery and to compare them with those of the intern al 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 mo unted on a strain gauge in oxygenated, normothermic Krebs' solution at optimal resting tension. With KCl (100 mM) serving as the control, th e dose-response curves to norepinephrine, serotonin, and thromboxane A 2 mimetic were obtained, permitting assessment of force of contraction and sensitivity. Functional endothelium was assessed with acetylcholi ne. Smooth muscle-dependent relaxation was assessed with sodium nitrop russide. The radial artery had stronger contractions to KCl than the o ther vessels. The radial and the gastroepiploic arteries with endothel ium presented a higher contraction force than the internal mammary art ery in response to norepinephrine and serotonin. The three vessels had equal sensitivities to norepinephrine and serotonin. The gastroepiplo ic artery had a lower sensitivity to thromboxane A2 mimetic than the t wo other vessels. Conclusions. This increased reactivity of the radial artery explains its propensity to spasm and emphasizes the need for a ntispastic drugs and platelet inhibitors when the radial artery is use d for coronary artery bypass.