From the Intervention Centre, Oslo University Hospital, Oslo, Norway.
Faculty of Medicine, University of Oslo, Oslo, Norway.
ASAIO J. 2020 Jan;66(1):38-48. doi: 10.1097/MAT.0000000000000954.
We have recently demonstrated that accelerometer-based pump thrombosis and thromboembolic events detection is feasible in vitro. This article focuses on detection of these conditions in vivo. In an open-chest porcine model (n = 7), an accelerometer was attached to the pump casing of an implanted HeartWare HVAD. Pump vibration was analyzed by Fast Fourier Transform of the accelerometer signals, and the spectrogram third harmonic amplitude quantified and compared with pump power. Interventions included injection of thrombi into the left atrium (sized 0.3-0.4 ml, total n = 35) and control interventions; pump speed change, graft obstruction, and saline bolus injections (total n = 47). Graft flow to cardiac output ratio was used to estimate the expected number of thrombi passing through the pump. Sensitivity/specificity was assessed by receiver operating characteristic curve. Graft flow to cardiac output ratio averaged 66%. Twenty-six of 35 (74%) thrombi caused notable accelerometer signal change. Accelerometer third harmonic amplitude was significantly increased in thromboembolic interventions compared with control interventions, 64.5 (interquartile range [IQR]: 18.8-107.1) and 5.45 (IQR: 4.2-6.6), respectively (p < 0.01). The corresponding difference in pump power was 3 W (IQR: 2.9-3.3) and 2.8 W (IQR: 2.4-2.9), respectively (p < 0.01). Sensitivity/specificity of the accelerometer and pump power to detect thromboembolic events was 0.74/1.00 (area under the curve [AUC]: 0.956) and 0.40/1.00 (AUC: 0.759), respectively. Persistent high third harmonic amplitude was evident at end of all experiments, and pump thrombosis was confirmed by visual inspection. The findings demonstrate that accelerometer-based detection of thromboembolic events and pump thrombosis is feasible in vivo and that the method is superior to detection based on pump power.
我们最近已经证明，基于加速度计的泵血栓形成和血栓栓塞事件检测在体外是可行的。本文重点关注体内这些情况的检测。在开胸猪模型中（n=7），将加速度计附着在植入的 HeartWare HVAD 的泵壳上。通过对加速度计信号进行快速傅里叶变换来分析泵的振动，并对频谱第三谐波幅度进行量化，并与泵功率进行比较。干预措施包括向左心房注射血栓（大小为 0.3-0.4ml，共 35 次）和对照干预措施；改变泵速、移植阻塞和盐水推注（共 47 次）。移植流量与心输出量的比值用于估计通过泵的血栓数量。通过接受者操作特征曲线评估敏感性/特异性。移植流量与心输出量的比值平均为 66%。35 个血栓中的 26 个（74%）导致明显的加速度计信号变化。与对照干预相比，血栓栓塞干预时加速度计第三谐波幅度显著增加，分别为 64.5（四分位距 [IQR]：18.8-107.1）和 5.45（IQR：4.2-6.6）（p<0.01）。相应的泵功率差异分别为 3 W（IQR：2.9-3.3）和 2.8 W（IQR：2.4-2.9）（p<0.01）。加速度计和泵功率检测血栓栓塞事件的敏感性/特异性分别为 0.74/1.00（曲线下面积 [AUC]：0.956）和 0.40/1.00（AUC：0.759）。所有实验结束时，第三谐波幅度均持续升高，且通过肉眼观察证实泵血栓形成。研究结果表明，基于加速度计的血栓栓塞事件和泵血栓形成的检测在体内是可行的，该方法优于基于泵功率的检测。
