The effect of the thoracic epidural anesthesia together with general anesthesia on the blood flow and on the endothelium of the internal thoracic artery in coronary artery bypass surgery

Aim: The internal thoracic artery (ITA) is the most commonly used graft in coronary artery bypass grafting (CABG) surgery with a highest patency. The aim of this paper was to investigate whether thoracic epidural anesthesia (TEA) as an adjunct to general anesthesia (GA) play a role on blood flow and endothelium of ITA in patients undergoing CABG.Materials and Methods: Thirty patients scheduled for elective CABG were randomized to receive either GA (n=15) or TEA+GA (n=15). There were no significant differences in demographics of patients between the groups. The epidural catheter was inserted in the thoracic region between T1 and T5 levels. In the TEA+GA group, bolus bupivacain was administered after induction of GA and then followed by continuous infusion of bupivacain during intraoperative period and for the first 24 h of the operation. Blood flow of ITA was measured before institution of cardiopulmonary bypass without administration of any topical or intraluminal vasodilator agent. A short segment of ITA was excised 2 cm proximal to its bifurcation for histological examination. Immunocytochemistry was performed using anti-adenosine A2B antibody, anti-rabbit polyclonal VEGF antibody and rabbit polyclonal i-NOS antibody. The immunoreactivity rates were then evaluated.Results: The mean blood flow rate of ITA was significantly higher in the TEA+GA group than the GA group (56.0±9.0 ml/min. vs. 39.6±14 ml/min.; p?0.001). All patients were discharged from the hospital without any complications. No mortality occurred during the follow-up period. Although adenosine, VEGF and i-NOS immunoreactivity were apparent in both groups, immunostaining intensity was greater in the TEA+GA group than the GA group.Conclusion: The result of this study indicate that TEA plus GA in coronary surgery increases ITA blood flow significantly via increased adenosine, VEGF and i-NOS levels. Therefore, TEA+GA might be considered as an alternative to topical and systemic vasodilators for reducing vasospasm in patients undergoing CABG.