Volume changes and pressure variations are fundamental determinants of ventricular functioning. Ventricular end-systolic elastance (Emax) depends on ejection pressure and end-systolic volume, whereas arterial elastance (Ea) refers to the ratio of ejection pressure and stroke volume. Coupling between left ventricle and arterial bed has often been quantitated by using the ratio of Emax and Ea. Reportedly, this ratio equals to one for optimal coupling conditions, but measurements in humans documented values considerably different from unity.We modelled the behavior of the left ventricle on the basis of the experimentally constructed Alternative Starling curve (ASC). Such relation describes the dynamic behavior of the volume regulation for the heart. This information was then applied to relate Emax/Ea to ejection fraction (EF). Our results indicate that Emax/Ea varies with the prevailing value of EF. Also, this outcome explains seemingly conflicting findings obtained in cardiac patients.