Steinlechner Barbara, Dworschak Martin, Birkenberg Beatrice, Duris Monika, Zeidler Petra, Fischer Henrik, Milosevic Ljubisa, Wieselthaler Georg, Wolner Ernst, Quehenberger Peter, Jilma Bernd
Division of Cardiothoracic and Vascular Anesthesia and Intensive Care, Medical University of Vienna, Vienna, Austria.
Ann Thorac Surg. 2009 Jan;87(1):131-7. doi: 10.1016/j.athoracsur.2008.10.027.
Thromboembolic and bleeding complications in outpatients with a left ventricular assist device are common and can be detrimental. A meticulous balance between anticoagulant and procoagulant factors is therefore crucial. However, in contrast to routinely performed plasmatic coagulation tests, platelet function is hardly ever monitored although recent reports indicated platelet dysfunction. We therefore differentially evaluated platelet function with four commonly used point-of-care devices.
In a cross-sectional design platelet function was assessed in 12 outpatients and 12 healthy matched volunteers using thrombelastography platelet mapping, thromboelastometry, platelet function analyzer, and a new whole blood aggregometer (Multiplate).
Phenprocoumon produced an international normalized ratio of 3.5. It was associated with a twofold prolongation in the thromboelastometry clotting time (p < 0.001). Platelet function under high shear was severely compromised: collagen adenosine diphosphate closure times were 2.5-fold longer in patients than in volunteers (p < 0.001), and 50% of patients had maximal collagen adenosine diphosphate closure time values. Although antigen levels of von Willebrand factor were 80% higher in patients (p < 0.001), von Willebrand factor-ristocetin was subnormal in 5 of 12 patients. Ristocetin-induced aggregation was also threefold higher in volunteers (p < 0.001), indicating an additional functional defect of platelets affecting the glycoprotein Ib-von Willebrand factor axis. The von Willebrand factor multimer pattern in patients also appeared abnormal.
Multimodal antiplatelet monitoring showed markedly impaired platelet function in patients with a left ventricular assist device. Platelet dysfunction under high shear rates and abnormal ristocetin-induced aggregation is only partly attributable to low von Willebrand factor activity. These findings resemble the acquired von Willebrand syndrome that is associated with microaggregate formation and enhanced bleeding.
左心室辅助装置门诊患者的血栓栓塞和出血并发症很常见，且可能有害。因此，抗凝和促凝因子之间的精确平衡至关重要。然而，与常规进行的血浆凝血试验不同，尽管最近的报告表明存在血小板功能障碍，但血小板功能几乎从未被监测过。因此，我们使用四种常用的即时检测设备对血小板功能进行了差异评估。
采用横断面设计，使用血栓弹力图血小板图谱、血栓弹力测定法、血小板功能分析仪和一种新型全血凝集仪（Multiplate），对12名门诊患者和12名健康匹配志愿者的血小板功能进行评估。
苯丙香豆素产生的国际标准化比值为3.5。它与血栓弹力测定凝血时间延长两倍有关（p < 0.001）。高剪切力下的血小板功能严重受损：患者的胶原二磷酸腺苷封闭时间比志愿者长2.5倍（p < 0.001），50%的患者胶原二磷酸腺苷封闭时间值达到最大值。尽管患者血管性血友病因子的抗原水平高80%（p < 0.001），但12名患者中有5名患者的血管性血友病因子-瑞斯托霉素水平低于正常。志愿者中瑞斯托霉素诱导的聚集也高三倍（p < 0.001），表明影响糖蛋白Ib-血管性血友病因子轴的血小板存在额外的功能缺陷。患者的血管性血友病因子多聚体模式也显得异常。
多模式抗血小板监测显示，左心室辅助装置患者的血小板功能明显受损。高剪切率下的血小板功能障碍和异常的瑞斯托霉素诱导聚集仅部分归因于低血管性血友病因子活性。这些发现类似于与微聚体形成和出血增加相关的获得性血管性血友病综合征。
