Thoracic epidural anesthesia (TEA) is increasingly used to reduce stress response, pain and pulmonary complication of patients under coronary artery bypass graft (CABG). However, effects of TEA on blood flow of grafted coronary artery are scarcely noticed. Imbalance between blood flow of grafted coronary artery and myocardial oxygen demand can bring about perioperative myocardial ischemia. Thus we evaluated the effect of TEA on blood flow of coronary grafts.

Twenty seven patients with triple-vessel coronary artery disease under CABG were recruited. Left internal mammary artery, radial artery, and great saphenous vein were anastomosed to left anterior descending artery, obtuse marginalis, and posterior descending artery, respectively. Before surgery, an epidural catheter was inserted. Total intravenous anesthesia was undertaken using fentanyl, midazolam and vecuronium. After grafts anastomosis, blood flow of grafted coronary artery was measured using transit-time flowmeter (TTFM) before weaning from CPB. And then, mixture of 2% lidocaine 10 ml, fentanyl 50µg and bicarbonate 1 mEq was injected via epidural catheter. Under the constant pump flow, the blood flow of grafted coronary artery before, 10 and 20 minutes after drug administration were measured using TTFM.

The blood flow of coronary artery grafts was similar in three time interval, irrespective of grafted artery. There are no significant differences in changes in coronary blood flow associated with epidural lidocaine injection among 3 types of grafted artery.

The present study shows that there are no significant effects of TEA on blood flow of newly grafted coronary artery after CABG.