LDL apheresis and its effect on viscosity
LDL apheresis and its effect on viscosity
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发表时间：
2003
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通讯作者：
P. Moriarty;C. Gibson
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作者：
P. Moriarty;C. Gibson
血液的血流动力学对血管系统有着重要的影响。粘度，即流动阻力，是血液流动的主要决定因素，并与心血管疾病直接相关。与血浆粘度不同，血液粘度是非牛顿流体，其不是恒定的，而是根据血液的剪切力和剪切速率而变化。血液流动越慢，粘度越高。小管腔血管（小动脉和毛细血管），外周阻力的主要调节器，可以极大地影响血液粘度。血液粘度的介质包括血细胞比容、红细胞（RBC）变形性、RBC聚集和血浆粘度。已发现血清胆固醇通过增加RBC变形性、RBC聚集性和血浆粘度来增加血液粘度。在这篇综述中，作者讨论了低密度脂蛋白（LDL）单采术，一个立即清除大量血清胆固醇的过程，对血管系统的影响。具体而言，他们强调了LDL单采的两种方法（即，Liposorber和HELP），在美国使用。这两种设备都可以在2-3小时内将LDL胆固醇降低60%-70%。它们还可以显著降低纤维蛋白原水平。低密度脂蛋白单采术可以显著减少红细胞聚集，改善红细胞变形，降低血浆粘度，尤其是当纤维蛋白原水平也降低时。LDL单采后血液粘度可降低20%。血液流变学的改善被认为是治疗后心肌血流量和速度立即增加的原因之一。在急性充血期间，当微循环系统处于应激状态时，LDL单采术可能通过其降低血液粘度的能力来改善血管流动和组织灌注。
The hemodynamics of blood have a significant effect on the vascular system. Viscosity, the resistance to flow, is a major determinant of blood flow and can be directly related to cardiovascular disease. Blood viscosity, unlike plasma viscosity, is a non-Newtonian fluid that is not constant but changes depending on the shear force and shear rate of the blood. The slower the blood flow the higher the viscosity. Small lumen vessels (arterioles and capillaries), the major regulators of peripheral resistance, can be greatly affected by blood viscosity. Mediators of blood viscosity include hematocrit, red blood cell (RBC) deformability, RBC aggregation, and plasma viscosity. Serum cholesterol has been found to increase blood viscosity by increasing RBC deformability, RBC aggregation, and plasma viscosity. In this review, the authors discuss the effects of low-density lipoprotein (LDL) apheresis, a process for immediately removing massive amounts of serum cholesterol, on the vascular system. Specifically, they highlight two methods of LDL apheresis (i.e., Liposorber and HELP), which are used in the United States. Both devices can deerease LDL cholesterol by 60%-70% in 2-3 hours. They can also significantly reduce fibrinogen levels. LDL apheresis can dramatically reduce RBC aggregation, improve RBC deformation, and lower plasma viscosity-especially when fibrinogen levels are also reduced. Blood viscosity can be lowered by as much as 20% following LDL apheresis. Improved hemorheology is believed to be one of the reasons for immediate enhancement of myocardial blood flow and velocity following treatment. During acute hyperemia, when the microcirculatory system is under stress, LDL apheresis might improve vascular flow and tissue perfusion through its ability to lower blood viscosity.