An acoustic method for systematic ventricular assist device thrombus evaluation with a novel artificial thrombus model
An acoustic method for systematic ventricular assist device thrombus evaluation with a novel artificial thrombus model
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DOI：
10.21037/jtd.2018.04.11
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发表时间：
2018-06-01
影响因子：
2.5
通讯作者：
Schmitto, Jan D.
中科院分区：
文献类型：
--
作者：
Feldmann, Christina;Deniz, Ezin;Schmitto, Jan D.
背景：泵血栓形成（PT）仍然是左心室辅助装置支持患者的主要不良事件之一。目前，血栓的检测依赖于临床参数，如再次出现的心力衰竭症状，泵功率的变化，以及实验室参数，如乳酸脱氢酶升高和溶血。一旦发现PT是最常见的持久性和难治性药物治疗。因此，我们设计了一种新颖的、无创的声学方法，用于体外人工血栓模型的早期泵血栓检测。方法：在体外使用模拟循环环、人工血液（水甘油）和人工血栓材料（硅）进行研究，允许重复和明确的测试。测试的心室辅助装置（VAD）类型为HVAD（美敦力）。评估了三种不同的血栓位置：在转子的倾斜垫上，在主流道上，在转子下方的次流道上。在评估基线参数（无血栓，每个泵n=20）后，通过麦克风系统（Sennheiser）和随后的频谱分析（n=12）研究了7种不同质量的血栓（无血栓，0.5-5.0 mg）对4个HVAD设备的泵功耗和声发射的影响。声学分析算法包括记录的频率峰值的数量。结果：倾斜垫上有血栓的测量显示，与没有血栓的基线测量相比，所有血栓大小的频率峰值数量都增加了（基线：32.7 +/- 7.4;0.5 mg: 45.3 +/- 10.4直到5mg: 80.4 +/- 5.5）。仅在5mg血栓测量时，功率消耗相关升高（6.3 +/- 1.29 W，而基线时为4.9 +/- 0.14 W）。原发性和继发性血栓的测量显示，功耗和频率峰值计数没有相关的变化。结论：我们提出了一种声学方法，可以检测位于HVAD转子倾斜垫上的泵血栓，与当前检测算法中使用的功耗改变检测的血栓相比，所需的质量减少了十倍。假设泵血栓在数天内生长，本方法可以更早地检测到PT，从而提高药物治疗的疗效，并有助于避免泵交换。
Background: Pump thrombosis (PT) is still one of the major adverse events in patients supported with left ventricular assist devices. Nowadays, thrombus detection relies on clinical parameters like reoccurring heart failure symptoms, on changes in pump power consumption, and on laboratory parameters such as increased LDH and hemolysis. Once detected PT is most often persistent and refractory to medical therapy. We therefore designed a novel, non-invasive acoustic method for early pump thrombus detection in an in vitro artificial thrombus model.Methods: The study was performed in vitro using a mock circulation loop, artificial blood (water-glycerin) and artificial thrombus material (silicon) allowing for repeatable and defined testing. Tested ventricular assist device (VAD) type was HVAD (Medtronic). Three different thrombus locations were evaluated: on the tilted pad of the rotor, in the primary flow path, and in the secondary flow path beneath the rotor. After evaluating baseline parameters (no thrombus, n=20 for each pump), the influence of thrombi of seven different masses (no thrombus, 0.5-5.0 mg) on pump power consumption and acoustic emission of four HVAD devices was investigated via a microphone system (Sennheiser) and subsequent frequency spectrum analysis (n=12). The acoustic analysis algorithm included the number of frequency peaks recorded.Results: Measurements with thrombi on the tilted pad showed an increased number of frequency peaks with all thrombus sizes compared to baseline measurements without any thrombus (baseline: 32.7 +/- 7.4; 0.5 mg: 45.3 +/- 10.4 up to 5 mg: 80.4 +/- 5.5). Power consumption was relevantly elevated in 5mg thrombus measurement only (6.3 +/- 1.29 W compared to 4.9 +/- 0.14 W at baseline). Measurements with thrombi in the primary and secondary showed no relevant alteration in power consumption and frequency peak count.Conclusions: We present an acoustic method that detects pump thrombi located on the tilted pad of the HVAD rotor requiring ten times less mass compared to thrombi detected by power consumption alterations used in current detection algorithms. Assuming that pump thrombi are growing over several days, the presented method may detect PT much earlier thereby increasing efficacy of medical therapy and helping to avoid pump exchange.