Relation between coupling index and ejection fraction and the alternative starting curve

Abstract

Abslract-Volume changes and pressure variations are fundamental determinants of ventrkuhr 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 coupliog 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 Nternative Starling curve (ASC). Such relation descritxs the dynamic behavior of the volume regulation for the heart. This information was then applied to relate Emax/Ea to ejection fraction (Em. Our results indicate that EmaxlEa varies with the prevailing value of EF. MO, this outcome explains seemingly conflicting findings obtained in cardiac patients.