The influence of device position on the flow within the Penn State 12 cc pediatric ventricular assist device.
The influence of device position on the flow within the Penn State 12 cc pediatric ventricular assist device.
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DOI：
10.1097/mat.0b013e3182639a18
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发表时间：
2012-09
期刊：
影响因子：
--
通讯作者：
Manning KB
中科院分区：
文献类型：
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作者：
Schönberger M;Deutsch S;Manning KB
心室辅助装置是一种常用的心力衰竭治疗成人患者作为桥移植或桥恢复的工具。成人心室辅助装置在儿科患者中的应用导致血栓事件增加。因此，我们一直在开发一种儿科心室辅助装置，宾夕法尼亚州立大学12cc PVAD。它是为体重在5至15公斤，卒中容积为12毫升的患者设计的，血栓形成是主要问题。它与血液的凝固性、血液接触材料和系统内的流体力学有关。目的是使PVAD成为一种长期治疗。因此，系统可以根据患者的行为定位在不同的位置。本研究首次评估了宾州州立大学12cc PVAD内位置对流动模式的影响，这可能有助于改进PVAD腔室和端口几何形状的设计。采用粒子图像测速技术对流体动力学进行了可视化。评估是基于入口射流行为和计算的壁面剪切率。对垂直和水平两种模式进行了比较，两种模式均以75次心跳、90/60 mmHg的出口压力和1.3 l/min的流量为条件。结果表明，进口射流特性发生了显著变化，并形成了旋转流型。在垂直方向上，进气道沿壁面射流很强。它启动一个旋转的流动模式与一个流浪的旋转轴。相比之下，水平模型方向的结果显示，沿壁面的入口射流较弱，旋转中心位置几乎恒定，这可能与血栓事件的高风险相关。此外，高速摄像显示了舒张期膈肌运动的差异。膜片打开轨迹测量确定没有明显的影响密度的血液模拟流体。因此，结果与人类血液有关。
Ventricular assist devices are a commonly used heart failure therapy for adult patients as bridge-to-transplant or bridge-to-recovery tool. The application of adult ventricular assist devices in pediatric patients has led to increased thrombotic events. Therefore, we have been developing a pediatric ventricular assist device, the Penn State 12 cc PVAD. It is designed for patients with a body weight of 5 to 15 kg and has a stroke volume of 12 cc. Clot formation is the major concern. It is correlated to the coagulability of blood, the blood contacting materials and the fluid dynamics within the system. The intent is for the PVAD to be a long term therapy. Therefore, the system may be oriented in different positions according to the patient’s behavior. This study evaluates for the first time the impact of position on the flow patterns within the Penn State 12 cc PVAD, which may help to improve the PVAD design concerning chamber and ports geometries. The fluid dynamics are visualized by particle image velocimetry. The evaluation is based on inlet jet behavior and calculated wall shear rates. Vertical and horizontal model orientations are compared, both with a beat rate of 75, outlet pressures of 90/60 mmHg and a flow rate of 1.3 l/min. The results show a significant change of the inlet jet behavior and the development of a rotational flow pattern. Vertically, the inlet jet is strong along the wall. It initiates a rotational flow pattern with a wandering axis of rotation. In contrast, the horizontal model orientation results show a weaker inlet jet along the wall with a nearly constant center of rotation location, which can be correlated to a higher risk of thrombotic events. In addition high speed videography illustrates differences in the diaphragm motion during diastole. Diaphragm opening trajectories measurements determine no significant impact of the density of the blood analog fluids. Hence, the results correlate to human blood.