Evaluation of vascular aging on measures of cardiac function and mechanical efficiency: insights from in-silico modeling

Introduction: This study evaluated the hypothesis that vascular aging (VA) reduces ventricular contractile function and mechanical efficiency (ME) using the left ventricular pressure-volume (PV) construct. Methods: A previously published in-silico computational model (CM) was modified to evaluate the hypothesis in two phases. In phase I, the CM included five settings of aortic compliance (C_A) from normal to stiff, studied at a heart rate of 80 bpm, and phase II included the normal to stiff C_A settings evaluated at 60, 100, and 140 bpm. The PV construct provided steady-state and transient data through a simulated vena caval occlusion (VCO). The steady-state data included left ventricular volumes (EDV and ESV), stroke work (SW), and VCO provided the PV area (PVA) data in addition to the three measures of contractile state (CS): end-systolic pressure-volume relationship (ESPVR), dP/dt_max-EDV and preload recruitable stroke work (PRSW). Finally, ME was calculated with the SW/PVA parameter. Results: In phase I, EDV and ESV increased, as did SW and PVA. The impact on the CS parameters demonstrated a small decrease in ESPVR, no change in dP/dt_max-EDV, and a large increase in PRSW. ME decreased from 71.5 to 60.8%, respectively. In phase II, at the normal and stiff C_A settings, across the heart rates studied, EDV and ESV decreased, ESPVR and dP/dt_max-EDV increased and PRSW decreased. ME decreased from 76.4 to 62.6% at the normal C_A and 65.8 to 53.2% at the stiff C_A. Discussion: The CM generated new insights regarding how the VA process impacts the contractile state of the myocardium and ME.