Detection of thrombosis in a magnetically levitated blood pump by vibrational excitation of the impeller
Detection of thrombosis in a magnetically levitated blood pump by vibrational excitation of the impeller
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DOI：
10.1111/aor.13632
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发表时间：
2020-02-05
影响因子：
2.4
通讯作者：
Maruyama, Osamu
中科院分区：
文献类型：
--
作者：
Hijikata, Wataru;Maruyama, Takuro;Maruyama, Osamu
非接触式叶轮支撑技术的使用提高了心室辅助装置（VAD）的耐用性，这些装置已在全球范围内临床使用。然而，泵血栓形成和中风仍然是有待解决的问题。我们已经开发了一种用于检测磁悬浮血泵中的血栓形成的方法，而不需要额外的传感器或其他设备。在所提出的方法中，正弦电流施加到用于磁轴承的电磁铁，导致叶轮的振动。泵内血栓形成时，电流与叶轮位移之间的相位差增大。首先，我们描述了检测泵血栓形成的原理。泵血栓形成减小了泵中的最后流体间隙，这引起相位差的变化。第二，我们报告的实验中，我们改变了最后一个流体间隙使用定向聚丙烯带，并表明，减少最后一个流体间隙导致相位差的增加。对于这些实验，对于每种条件重复测量三次。第三，我们检查了泵血栓形成和相位差之间的关系，通过观察使用猪血操作泵时的叶轮下侧来评估相位差。由于光无法穿透血层，因此取出红细胞进行观察。只提出了一项意见。结果表明，在观察到泵血栓形成的同时，相位差迅速增大。这意味着所提出的方法具有检测泵血栓形成的早期阶段的潜力。最后，进行了体外实验，以检测在泵中使用全血时的血栓形成。实验进行了五次。为了在泵内有意形成血栓，将活化凝血时间控制在200 s以内。在每种情况下，相位差在数十分钟后增加超过一度。然后，拆卸泵，观察到少量泵血栓形成。我们的结论是，实时诊断泵血栓形成可以实现通过测量相位差，而不需要额外的传感器。
The use of contactless support technology for the impeller has led to an increase in the durability of ventricular assist devices (VADs), and these have been in clinical use worldwide. However, pump thrombosis and stroke are still issues to be solved. We have developed a method for detecting the thrombosis in a magnetically levitated blood pump without the need for additional sensors or other equipment. In the proposed method, a sinusoidal current is applied to the electromagnets used for the magnetic bearing, resulting in vibration of the impeller. The phase difference between the current and displacement of the impeller increases with pump thrombosis. First, we describe the principle by which the pump thrombosis is detected. Pump thrombosis reduces the narrowest fluid gap in the pump and this gives rise to a change in the phase difference. Second, we report on experiments in which we changed the narrowest fluid gap using oriented polypropylene tape and showed that decreasing the narrowest fluid gap resulted in an increase in phase difference. For these experiments, the measurements were repeated three times for each condition. Third, we examine the relationship between the pump thrombosis and the phase difference evaluated by observations of the underside of the impeller when operating the pump with porcine blood. Since light was unable to penetrate the blood layer, the erythrocytes were removed for this observation. Only one observation was made. The results showed the phase difference rapidly increased at the same moment when the pump thrombosis was observed. This implies the proposed method has the potential to detect the early stages of pump thrombosis. Finally, in vitro experiments to detect thrombosis when using whole porcine blood in the pump were conducted. The experiment was carried out five times. To intentionally form a thrombus inside the pump, the activated clotting time was controlled to be less than 200 s. In every case, the phase difference increased by more than one degree after tens of minutes. Then, the pump was disassembled and a small amount of pump thrombosis was observed. We conclude that real-time diagnosis of pump thrombosis may be realized by measuring the phase difference without the need for additional sensors.