Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, Aachen, Germany.
Artif Organs. 2013 Sep;37(9):833-9. doi: 10.1111/aor.12116. Epub 2013 Jul 3.
Acquired von Willebrand Syndrome (AvWS) is known as a frequent bleeding complication in patients on ventricular assist device (VAD) support. Clinicians demand that the requirements for VADs with regard to hemocompatibility should also include low susceptibility for AvWS. Clinical AvWS diagnosis is known to be a complex, high-price, and time-consuming analysis. This article investigates an easy-to-handle, time-efficient, and inexpensive method for comparative AvWS investigations in vitro. Von Willebrand Factor activity level (vWF:Ac) and von Willebrand Factor antigen level (vWF:Ag) were chosen from the complete set of clinically established parameters. Blood plasma (human and porcine) was exposed to an inhomogeneous shear field in a shear-inducing test set up for up to 4 h. Plasma samples were drawn after different load periods and analyzed for vWF:Ac and vWF:Ag. vWF multimer analysis of selected samples were used as reference for determination of high molecular weight multimer (HMWM) loss. AvWS was detected after 20 min of shear load via vWF:Ac/vWF:Ag ratio and multimer analysis. A good correlation between the vWF:Ac/vWF:Ag ratio and HMWM loss (multimer analysis) was found for human plasma. AvWS characteristics of human and porcine plasma for analyzed samples were comparable. A correlation between vWF:Ac/vWF:Ag ratio and HMWM in porcine plasma could not be found. Results gained in this study indicate that vWF:Ac/vWF:Ag ratio is sensitive enough for comparative AvWS investigations in vitro with human blood. The applicability of the method suggested in this article for AvWS characterization in porcine blood needs to be investigated in further studies. The selection of analysis kits promises a less cost- and labor-intensive, time-consuming, and complex method for comparative AvWS investigations in vitro compared with AvWS diagnosis in patients.
获得性血管性血友病（AvWS）是心室辅助装置（VAD）支持患者常见的出血并发症。临床医生要求 VAD 对血液相容性的要求还应包括低易感性 AvWS。临床 AvWS 诊断已知是一种复杂、高成本和耗时的分析。本文研究了一种易于处理、高效和廉价的体外比较 AvWS 研究方法。选择了血管性血友病因子活性水平（vWF:Ac）和血管性血友病因子抗原水平（vWF:Ag）作为整套临床确立的参数。将血液血浆（人源和猪源）暴露于用于高达 4 小时的剪切诱导测试装置中的不均匀剪切场中。在不同的负载周期后抽取血浆样本，并分析 vWF:Ac 和 vWF:Ag。选定样本的 vWF 多聚体分析用作确定高分子量多聚体（HMWM）损失的参考。通过 vWF:Ac/vWF:Ag 比值和多聚体分析，在剪切负荷 20 分钟后检测到 AvWS。发现人血浆中 vWF:Ac/vWF:Ag 比值与 HMWM 损失（多聚体分析）之间存在良好的相关性。分析样本的人源和猪源血浆的 AvWS 特征具有可比性。在猪血浆中，vWF:Ac/vWF:Ag 比值与 HMWM 之间未发现相关性。本研究结果表明，vWF:Ac/vWF:Ag 比值对于体外比较 AvWS 研究非常敏感，可用于人血。需要进一步研究来确定本文提出的方法在猪血中用于 AvWS 特征描述的适用性。与患者的 AvWS 诊断相比，分析试剂盒的选择有望为体外比较 AvWS 研究提供一种成本更低、劳动强度更低、耗时更少且更复杂的方法。
