Coronary hyperperfusion and myocardial metabolism in isolated and intact hearts

The authors determined the independent influence of coronary hyperperfusion on myocardial metabolism in isolated and intact hearts. In an isovolumic blood-perfused rat heart preparation working against a left ventricular (LV) balloon, the effect of increasing coronary perfusion pressure from 100 to 150 mmHg was assessed. They concluded that coronary hyperperfusion was not an independent stimulus to myocardial VO2. To further test this, the effect of coronary hyperperfusion on myocardial metabolism was studied in an intact working swine heart preparation where the cardiac output was fixed with a right heart bypass circuit. Fatty acid oxidation in the left anterior descending bed was assessed by production of 14CO2 from [14C(U)]palmitate. They conclude that coronary hyperperfusion is not an independent determinant of myocardial oxidation or fatty acid utilization, and enhancement of mechanical function by the garden-hose effect appears to be dependent on the parameters of LV performance that are controlled