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Flow induced platelet activation in mechanical heart valves - numerical and in vitro studies

机译:机械心瓣中的流动诱导血小板激活 - 数值和体外研究

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Numerical studies and in vitro measurements were conducted, aimed at quantifying free emboli formation and procoagulant properties of platelets induced by flow past mechanical heart valves (MHV). Pulsatile turbulent flow simulation was conducted past a St. Jude medical MHV in the aortic position, to study the effects of valve implantation technique on the thromboembolic potential of the valve. A misaligned valve with subannualarly sutured pledgets produced accelerating jet flow through the valve orifices and a wider wake of shed vortices. Shear stress histories of platelets along turbulent trajectories exposed the platelets to elevated shear stresses around the leaflets, leading them to entrapment within the shed vortices. In vitro platelet studies were conducted past the MHV mounted in a recirculation flow loop, by measuring the platelets ability to support the activation of acetylated human prothrombin by factor xa. The acetylation results in the generation of thrombin that does not reactivate platelets during the assay, sequestering flow induced effects and enabling quantification of the platelets activity state at the time of removal from the flow loop. The platelet activation state increased monotonically as a function of the recirculation time past the valve, as measured by the thrombin generation rates in the assay.
机译:进行了数值研究和体外测量,旨在定量通过流过机械心脏瓣膜(MHV)诱导的血小板的自由栓子形成和促凝血性能。脉动湍流流动模拟通过主动脉位置的圣裘德医疗MHV进行,研究瓣膜注入技术对阀的血栓栓塞电位的影响。具有贱金利缝合防线的未对准阀,产生加速喷射流过阀孔和棚涡流的更宽唤醒。沿着湍流轨迹的血小板剪切应力历史暴露在传单周围的剪切应力升高,导致它们夹在棚涡流内。通过测量通过因子Xa致因子Xa的血小板能力,通过测量血小板能力,通过体外血小板研究过去安装在再循环流动回路中的MHV。乙酰化导致在测定期间不会重新激活血小板的凝血酶,螯合流动诱导的效果并使血小板活性状态的定量从流回路中移除。由于通过测定中的凝血酶产生速率测量,血小板激活状态随着瓣膜的再循环时间的函数而单调地增加。

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