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首页> 外文期刊>Artificial Organs >Hemodynamic Response to Exercise and Head-Up Tilt of Patients Implanted With a Rotary Blood Pump: A Computational Modeling Study
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Hemodynamic Response to Exercise and Head-Up Tilt of Patients Implanted With a Rotary Blood Pump: A Computational Modeling Study

机译：旋转血泵植入患者对运动和抬头倾斜的血流动力学响应：计算模型研究

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摘要

The present study investigates the response of implantable rotary blood pump (IRBP)-assisted patients to exercise and head-up tilt (HUT), as well as the effect of alterations in the model parameter values on this response, using validated numerical models. Furthermore, we comparatively evaluate the performance of a number of previously proposed physiologically responsive controllers, including constant speed, constant flow pulsatility index (PI), constant average pressure difference between the aorta and the left atrium, constant average differential pump pressure, constant ratio between mean pump flow and pump flow pulsatility (ratio(P)I or linear Starling-like control), as well as constant left atrial pressure (P) over bar (ta) control, with regard to their ability to increase cardiac output during exercise while maintaining circulatory stability upon HUT. Although native cardiac output increases automatically during exercise, increasing pump speed was able to further improve total cardiac output and reduce elevated filling pressures. At the same time, reduced venous return associated with upright posture was not shown to induce left ventricular (LV) suction. Although (P) over bar (ta) control outperformed other control modes in its ability to increase cardiac output during exercise, it caused a fall in the mean arterial pressure upon HUT, which may cause postural hypotension or patient discomfort. To the contrary, maintaining constant average pressure difference between the aorta and the left atrium demonstrated superior performance in both exercise and HUT scenarios. Due to their strong dependence on the pump operating point, PI and ratio(PI) control performed poorly during exercise and HUT. Our simulation results also highlighted the importance of the baroreflex mechanism in determining the response of the IRBP-assisted patients to exercise and postural changes, where desensitized reflex response attenuated the percentage increase in cardiac output during exercise and substantially reduced the arterial pressure upon HUT.
机译：本研究使用经过验证的数值模型，研究了植入式旋转血泵（IRBP）辅助患者对运动和抬头向上倾斜（HUT）的反应，以及模型参数值更改对此反应的影响。此外，我们比较评估了许多以前提出的生理响应控制器的性能，包括恒定速度，恒定流量脉动指数（PI），主动脉和左心房之间恒定的平均压力差，恒定平均差动泵压力，恒定的差压比。关于在运动时增加心输出量的能力方面，平均泵流量和泵流量脉动性（比率（P）I或线性Starling类控制），以及超过bar（ta）控制的恒定左心房压力（P）。在HUT上保持循环稳定性。尽管在运动过程中自然心输出量会自动增加，但提高泵速仍可以进一步改善总心输出量并降低充盈压。同时，未显示与直立姿势相关的静脉回流减少会诱发左心室（LV）抽吸。尽管（P）over bar（ta）控制在运动过程中增加心输出量的能力优于其他控制模式，但它会导致HUT的平均动脉压下降，这可能会导致体位性低血压或患者不适。相反，在运动和HUT情况下，在主动脉和左心房之间保持恒定的平均压力差表现出优异的性能。由于它们对泵工作点的强烈依赖性，因此在运动和HUT期间，PI和比率（PI）控制的效果很差。我们的模拟结果还强调了压力反射机制在确定IRBP辅助患者对运动和体位变化的反应中的重要性，其中脱敏反射反应减弱了运动过程中心输出量的百分比增加，并显着降低了HUT时的动脉压。

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