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Increasing the Transmitted Flow Pulse in a Rotary Left Ventricular Assist Device

机译：增加左旋心室辅助装置中的透射血流脉冲

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Long-term rotary left ventricular assist devices (LVADs) are increasingly employed to bridge patients with end-stage heart failure to transplant or as a destination therapy. Significant recent device development has increased patient support times, shifting further development focus toward physiologically sensitive control of the pump operation. Sensorless control of these devices would benefit from increased observability of the ventricular volume/preload to the pump, in order to regulate flow based on preload, imitating the native Frank-Starling flow control. Monitoring the transmitted flow pulse through the pump has been used as a surrogate for preload, although means of maximizing its transmission are not clear. However, it is known that a flat hydraulic performance curve of the rotary pump induces high changes in flow for a given change in pressure head. The aim of this study was to determine geometric pump parameters responsible for increasing this flow pulse transmission and to demonstrate this increase in vitro. The sensitivity of the performance gradient to blade angles, blade heights, blade clearance, and channel areas were studied. Resulting pressure head, flow, and hydraulic efficiency were analyzed with respect to textbook designed procedures. Then pumps with comparably "flat" and "steep" performance curves were used to simulate LVAD support in vitro over a range of pump flow rates to observe the transmitted flow pulsatility. It was found that an outlet blade angle of 90°, inlet blade angle between 25 and 45°, and large throat area generated a "flatter" performance curve. The transmitted flow pulsatility through a pump with a flat performance curve was 68% higher than that of a steep performance curve at a flow rate of 5L/min. Substantial gains in the observability of LVAD preload/resident blood volume in the ventricle exist through the careful selection of specific pump geometries.
机译：长期使用旋转左心室辅助设备（LVAD）来桥接患有终末期心力衰竭的患者进行移植或作为目的地治疗。最近的重大设备开发增加了患者支持时间，将进一步的开发重点转移到对泵操作的生理敏感控制上。这些设备的无传感器控制将受益于增加对泵的心室容积/预负荷的可观察性，以便根据预负荷来调节流量，从而模仿天然的Frank-Starling流量控制。监控通过泵传输的流量脉冲已被用作预紧的替代方法，尽管尚不清楚如何最大化其传输。然而，已知的是，对于给定的压头变化，旋转泵的平坦的液压性能曲线引起流量的高变化。这项研究的目的是确定造成这种流量脉冲传输增加的几何泵参数，并在体外证明这种增加。研究了性能梯度对叶片角度，叶片高度，叶片间隙和通道面积的敏感性。根据教科书设计的程序分析了产生的压头，流量和液压效率。然后将具有相对“平坦”和“陡峭”性能曲线的泵用于在一定范围的泵流量下体外模拟LVAD支撑，以观察传输的流量脉动。已经发现，出口叶片角度为90°，入口叶片角度在25至45°之间，并且喉部面积较大，这会产生“更平坦”的性能曲线。在流量为5L / min时，通过性能曲线平坦的泵传递的流量脉动比陡峭性能曲线的传递脉动性高68％。通过仔细选择特定的泵的几何形状，可明显提高LVAD预负荷/心室中的血容量。

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