The relationship between myocardial oxygen consumption and total work obtained by a new left ventricular model

The relationship between myocardial oxygen consumption (MVO2) and left ventricular work was examined experimentally, assuming that the left ventricle is equivalent to an electrical current source generator consisting of parallel source resistance (Ri) and constant generator current (I0). The internal and external work can be calculated as (Ri X I1(2)) and (Rp X I2(2)) in this model, where I1 is current of source resistance, Rp is peripheral resistance and I2 is cardiac output. The experiments were performed with a blood-perfused isolated ejecting canine heart preparation in which the hydraulic model, simulated to an aortic input impedance, was attached to the aortic root. The peripheral resistance was changed in a stepwise fashion and left ventricular pressure, cardiac output and MVO2 were measured. The calculated total work showed a close linear correlation with the MVO2, which suggested that the left ventricle can be regarded as a current source generator and the total work as a main mechanical factor in determining the MVO2.