Significance of Regional Ventriculo-arterial Coupling in Patients With Chronic Heart Failure

Heart failure is a major health problem worldwide. Optimal treatment of this disabling and fatal condition may require functional characterization of the failed left ventricle (LV) and its interaction with the arterial system. Part of the physiological significance of the ventriculo-arterial coupling has been studied experimentally and clinically using the framework of the ratio of effective arterial elastance (Ea) to end-systolic elastance (Ees), with limited clinical applications. From central ascending aorta to terminal arterioles, every segment of the arterial tree contributes to the arterial loads that interact and impact LV performance in both systole and diastole, leads to atrial and ventricular remodeling and hypertrophy, and results in the development of heart failure. On the other hand, the ventricular systole is a complex coordination of multi-directional myocardial fibers involving longitudinal contraction, circumferential shortening, radial thickening, twist, and torsion, the so-called LV deformations. The purposes of the present study are to investigate the relationship between different components of hemodynamic load or arterial abnormalities and different components of LV myocardial deformations or regional LV function, the modulating effects of endothelial progenitor cells (EPCs) on the ventriculo-arterial coupling, and the therapeutic effects of aliskiren on the components of hemodynamic load and LV myocardial deformations and their couplings. The investigators will also investigate whether the ventriculo-arterial coupling, EPCs, and add-on therapy of aliskiren predict cardiovascular outcomes.