Comparison of systemic vasodilators: Effects on flow in internal mammary and radial arteries

Background. Spasm is a major concern with the use of arterial conduits in c oronary artery bypass surgery (CABG). We evaluated the effect of systemic v asodilators on in vivo radial artery now compared with internal mammary art ery (IMA) now. Methods. Fifty patients undergoing primary CABG with a mean age of 69 +/- 5 years enrolled in this study and were randomized to 1 of 5 groups based on the vasodilating agent administered (nitroglycerin, nitroprusside, dobutam ine, milrinone, and normal saline as control group). Radial artery and IMA flows, blood pressure, central venous pressure, and heart rate were measure d before and 10 minutes after drug administration. Results. Mean arterial pressure decreased significantly after drug administ ration in both the nitroglycerin (p = 0.007) and nitroprusside (p < 0.001) groups and increased in the dobutamine group (p < 0.001). There were no sig nificant differences between IMA now or radial now among the groups before drug administration. A multivariate general linear model was created and re vealed drug (specifically nitroglycerin) as the only predictor to increase now in the IMA (p < 0.001) or the radial artery (p = 0.009). Conclusions. We conclude that intravenous nitroglycerin causes in vivo vaso dilatation of both the IMA and radial artery and is a good systemic vasodil ator to be given when harvesting these two conduits. (Ann Thorac Surg 2001; 71:138-41) (C) 2001 by The Society of Thoracic Surgeons.