CORONARY ARTERY DYNAMIC GEOMETRY AND ATHEROSCLEROSIS

这项研究的长期目标是：(1)确定血管系统的几何特征，这些特征增强了动脉对动脉粥样硬化性疾病的易感性，并可用于早期识别处于危险状态的个人，以及(2)了解机械因素在动脉粥样硬化的定位和病理生物学中的作用。为了实现第一个目标，寻找人体冠状动脉几何特征的活体测量与血管病理之间的关系，重点是早期病变。第二个目标是通过计算选定血管节段中流体动力学和壁内应力的分布，并寻找这些变量与活体测量的血管内膜和中层厚度之间的相关性来进一步实现第二个目标。俄亥俄州立大学和维克森林大学医学院的60名患者的临床双平面冠状动脉造影将被数字化处理，以重建选定的左前降支和右冠状动脉树节段的内轴的三维(3-D)过程。节段的定量几何参数，包括动脉几何的静态和动态测量以及血管运动学的测量，将使用客观的计算机算法从轴线获得。将评估不同个体之间几何形状的差异。将获得相同节段的血管内超声(IVUS)记录并进行处理，以产生与血管轴线配置的血管形态测量的详细测量结果。还将获得多普勒血流数据和相压力。将从血管造影术中寻找几何变量与从血管内超声记录中获得的形态测量参数之间的关系；分析将考虑与动脉粥样硬化的传统危险因素相关的个体变异性。血管造影的动态数据将用于模型计算，以估计血管运动和弯曲对流场和壁应力的影响。对于12例，血管造影和血管内超声记录将被用来描述舒张期部分血管的三维管腔和管壁。使用多普勒和压力数据作为输入，对该区域的流场和壁面应力进行了数值模拟；对第一个流动计算进行了实验验证。通过将计算的作用于血管节段的应力分布与血管内膜/中层厚度的应力分布进行比较，可以推断机械力在人体动脉粥样硬化中的作用。

The long-term objectives of this research are: (1) to identify geometric features of the vasculature that enhance arterial susceptibility to atherosclerotic disease and can be used for early identification of individuals accordingly at risk, and (2) to understand the role of mechanical factors in the localization and pathobiology of atherosclerosis. To achieve the first objective, relationships are sought between in vivo measurements of the geometric features of human coronary arteries and the pathology of the vessels, with a focus on the early lesion. The second objective is furthered by computing the distribution of fluid dynamic and intramural stresses in selected vessel segments, and seeking correlations between these variables and the thicknesses of the vascular intima and media, as measured in vivo. Clinical biplane coronary cineangiograms of sixty patients at The Ohio State University and Wake Forest University School of Medicine will be processed digitally to reconstruct the three- dimensional (3-D) course of the medial axes of selected segments of the left anterior descending and right coronary artery trees. Quantitative geometric parameters of the segments, including both static and dynamic measures of arterial geometry and measures of vessel kinematics, will be obtained from the axes using objective computer algorithms. Variations in geometry among individuals will be assessed. Intravascular ultrasound (IVUS) records of the same segments will be obtained and processed to yield detailed measurements of vessel morphometry collocated to the vessel axes. Doppler flow data and phasic pressure will also be acquired. Relations will be sought between the geometric variables from the angiograms and morphometric parameters derived from the IVUS records; and analysis will take into account individual variability with respect to the traditional risk factors for atherosclerosis. The dynamic data from the angiograms will be used in model calculations to estimate the effect of vessel motion and bending on the flow fieled and wall stresses. For twelve cases, the angiographic and IVUS records will be used to describe the 3-D lumen and wall of a portion of the vessel in diastole. The flow fieled and wall stresses in this region will be simulated numerically, using the Doppler and pressure data as input; the first flow calculation will be validated experimentally. By comparing the computed distribution of stresses acting on and in the vessel segment against that of intima/media thickness, inferences will be drawn regarding the role of mechanical forces in relation to human atherosclerosis.