Schilt S, Moore J E, Delfino A, Meister J J
Biomedical Engineering Laboratory, Swiss Federal Institute of Technology Lausanne, Switzerland.
J Biomech. 1996 Apr;29(4):469-74. doi: 10.1016/0021-9290(95)00082-8.
Blood flow patterns in the coronary arteries are of interest due to their possible involvement in atherosclerosis localization. Spatial variations in hemodynamic flow patterns are predominantly determined by the vessel geometry. The coronary arteries represent a unique situation in the cardiovascular system because their geometry undergoes large dynamic variations during each cardiac cycle due to the contraction of the heart. This study was initiated to analyze the effects of time-varying curvature on flow velocity profiles in a curved tube model of the coronary arteries. An in vitro flow model was constructed, which consisted of a flexible curved tube through which fluid flowed under a steady imposed pressure gradient. The radius of curvature of the tube was varied in time using a stepper motor and carriage. Two different deformation configurations were used to determine if variations in center of curvature displacement affected the velocity profiles. It was found in both cases that the skewing of the axial velocity profile depended on the instantaneous dynamic vessel movement, with maximal skewing occurring when the radius of curvature was in transition from the minimum to the maximum value. The change in skewing was greater for the case where carriage moved obliquely to the main direction of flow than when the carriage moved perpendicularly. Although this study was limited to relatively low values of the radius of curvature and change in curvature, an initial understanding of this flow situation was obtained which may lead to the development of more physiologic models.
冠状动脉中的血流模式因其可能与动脉粥样硬化的定位有关而备受关注。血流动力学模式的空间变化主要由血管几何形状决定。冠状动脉在心血管系统中呈现出独特的情况，因为由于心脏的收缩，其几何形状在每个心动周期中都会经历较大的动态变化。本研究旨在分析时变曲率对冠状动脉弯曲管模型中流速分布的影响。构建了一个体外流动模型，该模型由一个柔性弯曲管组成，流体在稳定的外加压力梯度下通过该管流动。使用步进电机和滑架使管的曲率半径随时间变化。采用两种不同的变形配置来确定曲率中心位移的变化是否会影响速度分布。在这两种情况下都发现，轴向速度分布的偏斜取决于瞬时动态血管运动，当曲率半径从最小值过渡到最大值时，偏斜最大。与滑架垂直移动的情况相比，滑架向流动主方向倾斜移动时偏斜的变化更大。尽管本研究仅限于相对较低的曲率半径值和曲率变化，但对这种流动情况有了初步的了解，这可能会促使开发更符合生理的模型。
