Blagojević Milan, Nikolić Aleksandar, Zivković Miroslav, Zivković Milorad, Stanković Goran
Vojnosanit Pregl. 2014 Mar;71(3):285-92. doi: 10.2298/vsp1403285b.
BACKGROUND/AIM: Practical difficulties, particularly long model development time, have limited the types and applicability of computational fluid dynamics simulations in numerical modeling of blood flow in serial manner. In these simulations, the most revealing flow parameters are the endothelial shear stress distribution and oscillatory shear index. The aim of this study was analyze their role in the diagnosis of the occurrence and prognosis of plaque development in coronary artery bifurcations.
We developed a novel modeling technique for rapid cardiovascular hemodynamic simulations taking into account interactions between fluid domain (blood) and solid domain (artery wall). Two numerical models that represent the observed subdomains of an arbitrary patient-specific coronary artery bifurcation were created using multi-slice computed tomography (MSCT) coronagraphy and ultrasound measurements of blood velocity. Coronary flow using an in-house finite element solver PAK-FS was solved.
Overall behavior of coronary artery bifurcation during one cardiac cycle is described by: velocity, pressure, endothelial shear stress, oscillatory shear index, stress in arterial wall and nodal displacements. The places where (a) endothelial shear stress is less than 1.5, and (b) oscillatory shear index is very small (close or equal to 0) are prone to plaque genesis.
Finite element simulation of fluid-structure interaction was used to investigate patient-specific flow dynamics and wall mechanics at coronary artery bifurcations. Simulation model revealed that lateral walls of the main branch and lateral walls distal to the carina are exposed to low endothelial shear stress which is a predilection site for development of atherosclerosis. This conclusion is confirmed by the low values of oscillatory shear index in those places.
背景/目的：实际困难，尤其是较长的模型开发时间，限制了计算流体动力学模拟在血流数值建模中的类型和适用性。在这些模拟中，最具揭示性的血流参数是内皮剪切应力分布和振荡剪切指数。本研究的目的是分析它们在冠状动脉分叉处斑块形成的发生诊断和预后中的作用。
我们开发了一种新颖的建模技术，用于快速进行心血管血液动力学模拟，同时考虑流体域（血液）和固体域（动脉壁）之间的相互作用。使用多层计算机断层扫描（MSCT）冠状动脉造影和血流速度超声测量，创建了两个代表任意患者特定冠状动脉分叉观察子域的数值模型。使用内部有限元求解器PAK-FS求解冠状动脉血流。
一个心动周期中冠状动脉分叉的整体行为通过以下参数描述：速度、压力、内皮剪切应力、振荡剪切指数、动脉壁应力和节点位移。（a）内皮剪切应力小于1.5以及（b）振荡剪切指数非常小（接近或等于0）的部位容易形成斑块。
采用流固相互作用的有限元模拟来研究患者特定的冠状动脉分叉处的血流动力学和血管壁力学。模拟模型显示，主分支的侧壁和隆突远端的侧壁受到低内皮剪切应力作用，这是动脉粥样硬化发展的偏好部位。这些部位振荡剪切指数的低值证实了这一结论。
