The effects of 1.5 MAC [minimum anesthetic concentration] isoflurane-nitrous oxide anesthesia on central hemodynamics, regional coronary blood flow, myocardial oxygenation and lactate balance were investigated in 13 patients with coronary artery disease. Mean arterial pressure was reduced 45% mainly because of systemic vasodilation. Great cardiac venous flow (GCVF) decreased, whereas total coronary sinus blood flow (CSF) was unchanged. Total coronary resistance and resistance in the area drained by the GCVF decreased as did myocardial O2 extraction, demonstrating coronary vasodilation. The GCVF/CSF ratio did not decrease despite the reduction in resistance to left ventricular ejection. Seven patients had ECG and metabolic indications of myocardial ischemic (lactate extraction reduced from 22 .+-. 5% to 7 .+-. 3%, P < 0.02 for the group). Changes in GCVF and O2 comsumption in the corresponding area correlated closely (r = 0.943). However, the regression line was shifted to the left and 3 patients, who became ischemic, had an increase in GCVF despite unchanged or decreased myocardial O2 demand. Isoflurane may cause coronary blood flow redistribution with regional myocardial ischemic in patients with coronary artery disease.