Myocardial blood flow and oxygen consumption during halothane-nitrous oxide anaesthesia for coronary revascularization.

The effects of halothane on myocardial blood flow and myocardial oxygen balance were studied in seven male patients with stable angina and normal left ventricular function. Patients were receiving maintenance doses of beta-receptor antagonists and underwent coronary artery bypass surgery. Anaesthesia consisted of halothane and 50% nitrous oxide in oxygen. Halothane decreased myocardial blood flow and myocardial oxygen consumption by 29% and 32%, respectively, after induction of anaesthesia, and during sternotomy. Myocardial lactate production was not observed at any time. Cardiac index, stroke volume index, mean arterial pressure and mean diastolic arterial pressure were decreased significantly after induction of anaesthesia and during sternotomy. Heart rate remained unchanged. The global myocardial oxygen supply and demand relationship was maintained. The results suggest that halothane is a safe anaesthetic for coronary revascularization in patients with unimpaired left ventricular function.