Computed zero-load flow, q s ( t), is the expected aortic flow at zero aortic input impedance, thus eliminating the effect of afterload on ventricular ejection. It is computed from an equivalent model of the ventricle using the Fourier components of left ventricular (LV) pressure and aortic flow, q a ( t), of two consecutive beats with different input impedance produced by partial aortic occlusion. Actual q s ( t) may be measured during the first beat after transection of the aorta. In animal experiments computed q s ( t) was similar to the waveform and magnitude of actual q s ( t) and was sensitive to inotropic interventions. A relationship between zero-load flow and parameters of cardiac muscle mechanics is derived from the Thévenin equivalent model of the pumping function of the ventricle and the three dimensional force-velocity-length diagram. The present analysis indicates that aortic flow can be expressed as the difference of afterload-independent zero-load flow and externally-controlled afterload-dependent internal flow.