低密度脂蛋白在颈动脉中输运与沉积的数值模拟及其影响因素

Numerical Study on Low-Density Lipoprotein Transport and Deposition in Carotid Arteries and the Associated Factors

目的研究低密度脂蛋白(low-density lipoproteins,LDL)在颈动脉中的输运和壁面沉积规律,分析其与血流动力学、形态学参数的关联性,为基于LDL壁面沉积特征及其关联因素评估颈动脉粥样硬化风险和易感位置提供理论参考。方法基于医学图像对6名健康志愿者的颈动脉构建个性化模型,数值模拟LDL在脉动流条件下的输运及其在血管壁的沉积过程,并量化分析LDL壁面沉积浓度、浓度极化区域面积等与血流速度和颈动脉形态学参数的关联性。结果 LDL沉积常出现在靠近颈总动脉远端的颈动脉窦部,其沉积程度和分布特征存在明显的个体差异。沉积程度主要由流速决定,流速越小,LDL壁面沉积程度越高,相应的浓度极化区域面积越大;而沉积的空间分布主要受几何形态特别是分叉偏心率的影响,依分叉偏心率可呈环状分布和单侧分布两种典型的形式。结论颈动脉血流速度和形态学特征是分别决定LDL沉积程度和分布特征的主要因素,对其进行个性化测量有助于识别颈动脉粥样硬化高风险个体及易感区域。

Objective To investigate the transport and deposition behaviors of low-density lipoproteins( LDL) in the carotid artery and explore their associations with hemodynamic and morphological factors,so as to provide theoretical references for assessing the risk and predisposing regions of atherosclerosis based on the characteristics and associated factors of LDL deposition at the carotid artery wall.Methods Subject-specific computational models of the carotid artery based on medical images from six healthy volunteers were built,and the transport and wall deposition of LDL under pulsatile flow conditions were simulated,and finally the correlations of wall LDL concentration and total area of regions with LDL concentration polarization with flow velocity and morphological parameters of the carotid artery were quantitatively analyzed.Results Regions with significant LDL deposition often appeared in carotid sinus near distal end of the common carotid artery,with the degree and spatial distribution of deposition differing considerably among subjects.The degree of LDL deposition was determined mainly by flow velocity,i.e.,the lower the flow velocity was,the higher the degree of LDL deposition and accordingly the larger the area of wall regions with LDL concentration polarization was;whereas the spatial distribution of LDL deposition was significantly affected by morphological characteristics( especially bifurcation eccentricity ratio) of the carotid artery,for example,the distribution patterns could be divided into two typical types( i.e.,circular distribution,unilateral distribution) according to bifurcation eccentricity ratio.Conclusions Flow velocity and morphological characteristics of the carotid artery are major factors determining respectively the degree and spatial distribution of LDL deposition,and therefore subject-specifically measuring these parameters will provide useful information for screening individuals at high risk of atherosclerosis or identifying atheroprone regions.