WALL SHEAR STRESS IN THE CARDIOVASCULAR SYSTEM

心血管系统中的壁剪切应力

• 批准号: 3349528
• 负责人: JOHN M TARBELL
• 金额: $ 14.7万
• 依托单位: PENNSYLVANIA STATE UNIVERSITY, THE
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-12-01 至 1996-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3349528
• 关键词: aorta; atherosclerosis; blood vessels; cardiovascular function; cardiovascular pharmacology; computer simulation; dogs; elasticity; hemodynamics; mathematical model; mechanical stress; model design /development; tissue /cell culture; vasoactive agent

The shear stress of flowing blood on arterial walls plays an important role in cardiovascular homeostasis, influencing a broad spectrum of processes including: the coagulation of blood and formation of thrombi, the adhesion of blood cells to surfaces, the production of vasoactive chemicals by endothelial cells, the turnover rate of endothelial cells, and the permeability of artery walls to macromolecules. Many of these processes are believed to play a role in the localization of atherosclerotic plaques in curved and branched arteries and the development of intimal hyperplasia in the anastomotic region of vascular grafts. In spite of the importance of wall shear stress in cardiovascular function, its magnitude and distribution in the circulation are not well known at present because of difficulties associated with direct in vivo measurement. Thus the broad objectives of the proposed research are to determine the distribution and magnitude of wall shear stress in the cardiovascular system; the physical factors which are most influential in the determination (e.g., geometry, fluid rheology, wall mechanics, systemic impedance ...); and the possibilities for manipulation of wall shear stress through vasoactive drugs. The research design involves close interaction among in vivo and in vitro experiments and computer simulations. In the proposed research the following studies will be conducted: 1. Wall shear rate will be measured in the thoracic aorta and the aortic arch of dogs under normal and drug-altered hemodynamic conditions. Flush mounted hot film anemometry will be used for the measurements. 2. Wall shear stress and associated velocity profiles will be measured in elastic (moving wall) models of curved and branched arteries and vascular graft anastomoses using Newtonian and non-Newtonian blood analog fluids. The photochromic method, a non-disturbing flow visualization technique, will be used for measurement of velocity profiles from which wall shear rates will be calculated. 3. Computer simulations of velocity fields and wall shear stress distributions in atherogenic curved and branched artery models taking into account realistic fluid rheology and wall mechanics will be developed. Finite difference schemes developed in collaboration with computational fluid dynamicists at NASA-Ames will be applied to realistic physiological flow simulations.

动脉壁上流动的血液的剪切应力起着重要作用 在心血管稳态中发挥作用，影响广泛 过程包括：血液凝固和血栓形成， 血细胞与表面的粘附，血管活性物质的产生 内皮细胞的化学物质，内皮细胞的周转率， 以及动脉壁对大分子的渗透性。 其中许多 流程被认为在本地化中发挥着作用 弯曲动脉和分支动脉中的动脉粥样硬化斑块 血管吻合区内膜增生的发展 移植物。 尽管壁面剪应力在 心血管功能、其大小和分布 由于困难，目前流通并不为人所知 与直接体内测量相关。 因此，广泛的目标 拟议研究的目的是确定分布和幅度 心血管系统中的壁剪切应力；物理因素 对测定影响最大的因素（例如几何形状、流体 流变学、壁力学、系统阻抗……）；和可能性 用于通过血管活性药物操纵壁剪切应力。 这 研究设计涉及体内和体外的密切相互作用 实验和计算机模拟。 在拟议的研究中，将进行以下研究： 1. 将测量胸主动脉和主动脉的壁剪切率。 正常和药物改变血流动力学状态下狗的主动脉弓 状况。 嵌入式热膜风速计将用于 测量。 2. 将测量壁剪应力和相关的速度分布 在弯曲和分支动脉的弹性（移动壁）模型中 使用牛顿和非牛顿血液进行血管移植吻合术 模拟流体。 光致变色方法，无干扰流动 可视化技术，将用于速度测量 计算壁剪切率的剖面。 3. 速度场和壁面剪应力的计算机模拟 致动脉粥样硬化弯曲和分支动脉模型中的分布 考虑到现实的流体流变学和壁力学将 发达。 与以下机构合作开发的有限差分方案 NASA-Ames 的计算流体动力学家将应用于 真实的生理流动模拟。