A left ventricular assist device (LVAD) is a surgically implanted mechanical pump being used for patients with end-stage heart failure (HF). One of the significant clinical challenges in using LVADs is its remarkable changes in hemodynamic parameters during a change in body position from supine to standing. In standing position, vasodilatation of veins occurs in the legs, which decreases left ventricular end-diastolic pressure, and, in turn, the preload to the LVAD. In this research, a numerical investigation is carried out to evaluate the effect of LVAD in cardiac hemodynamic parameters such as cardiac output (CO) and stroke work (SW) under preload, normal, and afterload conditions. A Proportional–integral–derivative (PID) controller associated with an LVAD pump model and cardiovascular system (CVS) model is developed to study the cardiac hemodynamic and its performance during HF condition by changing system parameters in one cardiac cycle. The performance of the proposed model is then evaluated using a pump cannulae model, real-time status detection of the aortic valve (av), and left ventricular stroke volume. The model parameters associated with HF, including contractility of the left and right ventricle ([Formula: see text] & [Formula: see text]), systemic peripheral resistance ([Formula: see text]) and total blood volume ([Formula: see text]) were set 0.71[Formula: see text]mmHg.s.mL[Formula: see text], 0.53[Formula: see text]mmHg.s.mL[Formula: see text], 1.11[Formula: see text]mmHg.s.mL[Formula: see text] and 5800[Formula: see text]mL, respectively, to allow simulation of HF conditions. The findings of this study show that the CO is increasing linearly with end-diastolic left ventricular volume (LVEDV) and end-diastolic right ventricular volume (RVEDV). However, other vital parameters behavior has a nonlinear relation to CO. Results of this study prove that the LVAD model is more sensitive to preload than afterload condition under different hemodynamical conditions.

中文翻译：

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心力衰竭患者使用心室辅助装置的前负荷和后负荷敏感性的数值研究

左心室辅助装置 (LVAD) 是一种手术植入的机械泵，用于终末期心力衰竭 (HF) 患者。使用 LVAD 的重大临床挑战之一是其在从仰卧位到站立位的体位变化过程中血流动力学参数的显着变化。站立时，腿部静脉发生血管扩张，从而降低左心室舒张末期压力，进而降低 LVAD 的预负荷。在这项研究中，进行了一项数值研究，以评估 LVAD 在前负荷、正常和后负荷条件下对心脏血流动力学参数的影响，例如心输出量 (CO) 和中风功 (SW)。开发了一种与 LVAD 泵模型和心血管系统 (CVS) 模型相关的比例积分微分 (PID) 控制器，通过在一个心动周期中改变系统参数来研究心脏血流动力学及其在 HF 条件下的性能。然后使用泵插管模型、主动脉瓣 (av) 的实时状态检测和左心室每搏输出量来评估所提出模型的性能。与 HF 相关的模型参数，包括左右心室的收缩力（[公式：见正文] & [公式：见正文]）、全身外周阻力（[公式：见正文]）和总血容量（[公式：见正文]) 设置为 0.71[公式：见正文]mmHg.s.mL[公式：见正文]、0.53[公式：见正文]mmHg.s.mL[公式：见正文]、1.11[公式：见正文]mmHg.s.mL[公式：见文本]和 5800[公式：见文本]mL，分别用于模拟 HF 条件。本研究的结果表明，CO 随舒张末期左心室容积（LVEDV) 和舒张末期右心室容积 (RVEDV）。然而，其他生命参数行为与 CO 呈非线性关系。本研究结果证明，在不同的血流动力学条件下，LVAD 模型对前负荷比后负荷更敏感。