The cardioprotective effects of thoracal epidural anesthesia are induced by the expression of vascular endothelial growth factor and inducible nitric oxide synthase in cardiopulmonary bypass surgery

Abstract

Aim The cardioprotective effects of thoracal epidural anesthesia (TEA) are induced by the expression of vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (i-NOS) in cardiopulmonary bypass (CPB) surgery. When general anaesthesia (GA) is combined with TEA during coronary artery bypass graft, we investigated whether TEA together with GA play a role on VEGF and i-NOS expression in human heart tissue in cardiac ischemia. Methods. Right atrial biopsy samples were taken before CPB, before aortic cross clamp (ACC) and at 15 min after ACC release (after ischemia and reperfusion). Human heart tissues were obtained from the TEA+GA and GA groups. immunocytochemistry was performed using antibodies for VEGF and i-NOS. Results. Both VEGF and i-NOS immunoreactivity was observed in cardiomyocytes; and arteriol walls. Although VEGF and i-NOS immunoreactivity was apparent in both groups,, immunostaining intensity was greater in the TEA+GA group than the GA group. Between groups, at 4 h and at 24 h after the end of CPB, the cardiac index (0) was significantly higher in the TEA+GA group than GA group (3.4 +/- 0.8 L/min/m(2) vs 2.5 +/- 0.8 L/min/m(2); P<0.001), (3.8 +/- 1.1 L/min/m(2) vs 3.1 +/- 1.1 L/min/m(2); P<0.008) respectively. Within groups, at 4 and 24 h after the end of CPB, the CI was significantly higher in the TEA+GA group than baseline values, (3.4 +/- 0.8 L/min/m(2) vs 2.4 +/- 0.7 L/min/m(2); P<0.001), (3.8 +/- 1.1 L/min/m(2) vs 2.4 +/- 0.7 L/min/m(2); P<0.001) respectively, but no difference was found in the GA group (2.6 +/- 0.8 L/min/m(2) vs 2.5 +/- 0.8 L/min/m(2); P>0.05),(2.6 +/- 0.8 L/min/m(2) vs 3.1 +/- 1.1 L/min/m(2); P>0.05) respectively. After ACC release, 11/40 (27.5%) patients in the TEA+GA group showed ventricular fibrillation (VF), atrial fibrillation or heart block versus 25/40 (62.5%) of those in the GA group. VF after ACC release in the TEA+GA group (9/20 patients, 22.5%) was significantly lower than in the GA group (21/40 patients, 52.5%); (P<0.006). Sinus rhythm after ACC release in the TEA+GA group (29/40 patients, 72.5%) was significantly higher than in the GA group (15/40 patients, 37.5%); (P<0.002). Conclusion. The results of the present study indicate that TEA plus GA in coronary surgery preserve cardiac function via increased expression of VEGF and i-NOS, improved hemodynamic function and reduced arrhythmias after ACC release.