Halothane improves the balance of oxygen supply to demand in acute experimental myocardial ischaemia.

Acute myocardial infarction was induced by ligation of the anterior descending branch of the left main coronary artery in greyhound dogs anaesthetized with pentobarbitone. Blood flow in the area of ischaemia was measured by xenon clearance and compared with flow in the circumflex artery measured with electromagnetic flow meters. Halothane 1% produced an approximate 40% reduction in flow to both ischaemic and normal areas in association with a 20% reduction in collateral perfusion pressure and a 40% reduction in mean arterial pressure. Comparison of the percentage change in the ratio of oxygen availability/consumption in response to halothane revealed a significant difference between the ischaemic and the normal areas. The former increased to 113 +/- 9.3% (mean +/- SEM) whilst the latter decreased to 91 +/- 5.02%. This suggests that, in the non-failing heart, halothane improves oxygenation in areas of acute myocardial ischaemia.