脉动式灌注中肝脏血管动力学特性研究

发布时间：2018-05-04 05:33

本文选题：肝移植 + 血管灌注　；参考：《天津理工大学》2017年硕士论文

【摘要】：肝脏是人体代谢的一种重要器官,肝衰竭会对人体的健康造成恶劣的影响。目前,对肝衰竭彻底治疗的重要手段是肝脏移植手术。由于供肝来源少,导致可用的优质肝供体相对紧缺,使得医疗现场采用边缘肝供体的可能性也越来越大,提高肝供体的质量将变成关键问题。肝脏灌注是移植手术前清洗和保存环节中的核心,采用适宜的肝脏灌注方法是更好的清除异物和保护肝脏组织的保障,也能够减少缺血或异常受力变化对其血管和器官组织造成损伤,同时有利于术后快速恢复。研究方法:本文基于恒流灌注方法存在的缺点和现阶段缺乏医用灌注液参数的研究基础上,提出两种全新的肝脏灌注方法,对称式脉动流和非对称式脉动流。通过研究灌注仿真过程中的动力学特性,阐明新的灌注方法的可行性。研究中首先构建了一级直血管、一级狭窄直血管、一级狭窄弯曲血管、一级非平滑血管以及不同角度的分支血管模型,并给出管内流体、管壁及流-固耦合控制方程。然后,基于双向流-固耦合分析,将新提出的两种肝脏灌注方法应用到不同几何形状的三维弹性肝脏血管模型中进行血管灌注仿真,模拟血管壁的运动及灌注液在血管内的流动。最后,分析肝脏血管灌注中动力学特性(主要包括流速、剪切力及血管变形等)的变化,并与恒流灌注的仿真数据进行对比,研究比较了不同几何形状的血管模型在灌注过程中其血管动力学特性的差异,说明本文提出的新的灌注方法的可行性。研究结果:采用多用途有限元仿真分析软件ANSYS进行灌注仿真模拟,仿真结果清晰地显示了血管内的流体动力学行为。对某一种特定几何形状的血管模型分别采用对称式脉动流、非对称式脉动流和恒流的灌注方法进行灌注仿真时,血管内灌注液的流速、血管变形和流-固耦合交界面剪切力的变化规律基本相同。在灌注液成功带走异物的前提下,对称式脉动流灌注时血管壁产生的变形要小于恒流灌注时血管壁产生的变形,即该灌注过程减弱了血管壁的径向运动,降低了血管壁的变形带来的肝脏血管组织损伤;采用非对称式脉动流灌注时血管壁产生的变形均小于恒流灌注时血管壁产生的变形,而且第二非对称式脉动流灌注时的血管变形小于第一非对称式脉动流灌注时的变形。血管单位横截面流过相同流量的灌注液时,不同几何形状的血管模型在不同灌注方法下的血管动力学特性不同,但对称式脉动流的灌注仿真效果优于其他灌注方法产生的结果。研究结论:研究结果表明,本文提出的新的灌注方法是可行的,研究不同肝脏灌注方法和血管几何模型对灌注仿真过程中的动力学特性产生的影响,为临床医疗改变灌注参数以改善肝供体质量提供理论依据。
[Abstract]:The liver is an important organ for human metabolism, and liver failure will have a bad effect on the health of the human body. At present, liver transplantation is an important means of complete treatment for liver failure. Because of the lack of donor liver, the available high quality liver donor is relatively tight, and the possibility of using the marginal liver donor in the medical site is becoming more and more likely. The quality of the high liver donor will become a key problem. Liver perfusion is the core of cleaning and preservation before transplantation. The appropriate liver perfusion method is a better guarantee for removing foreign bodies and protecting liver tissue, and can also reduce the damage to blood vessels and organs by ischemia or abnormal stress changes, and is beneficial to the post operation. Fast recovery. Research methods: Based on the shortcomings of the constant current perfusion method and the lack of medical perfusion parameters at the present stage, two new liver perfusion methods, symmetrical pulsating flow and asymmetric pulsating flow are proposed in this paper. By studying the dynamic characteristics of the perfusion simulation, the feasibility of the new perfusion method is clarified. First, the first order straight vessel, first order narrow straight blood vessel, first order narrow curved vessel, first order non smooth blood vessel and different angle branch vessel model are constructed, and the internal fluid, tube wall and flow solid coupling control equation are given. Then, based on two-way flow solid coupling analysis, the new two kinds of liver perfusion methods are applied to not In the three-dimensional elastic liver vascular model of the same geometry, the blood vessel perfusion simulation is simulated, the movement of the blood vessel wall and the flow of the perfusion fluid in the blood vessel are simulated. Finally, the changes of the dynamic characteristics (including the flow velocity, shear force and blood vessel deformation, etc.) in the liver blood vessel perfusion are analyzed and compared with the simulation data of the constant flow perfusion, and the comparison is made to study the comparison. The difference of vascular dynamic characteristics of vascular models with different geometric shapes in the process of perfusion indicates the feasibility of the new method of perfusion proposed in this paper. The results of the study are: using the multi purpose finite element simulation analysis software ANSYS to simulate the perfusion simulation, and the simulation results clearly show the fluid dynamic behavior in the blood vessel. When the vascular models of specific geometry are symmetrical pulsation flow, asymmetric pulsating flow and constant flow perfusion method, the flow velocity of intravascular perfusion, vascular deformation and flow to solid coupling interface shear force are basically the same. Under the premise of successful removal of foreign objects, the symmetrical pulsation flow is carried out. The deformation of the vascular wall is less than that of the vascular wall during perfusion, that is, the perfusion process reduces the radial movement of the vascular wall and reduces the damage of the vascular tissue caused by the deformation of the vascular wall, and the deformation of the vascular wall produced by the asymmetric pulsation flow is smaller than that produced by the blood vessel wall during the constant flow perfusion. The vascular deformation of the second asymmetric pulsating flow is less than that of the first asymmetric pulsating flow. When the unit cross section of the vessel flows through the same flow of perfusion, the vascular dynamics of the vascular models of different geometric shapes are different under different perfusion methods, but the simulation effect of the perfusion of symmetrical pulsating flow The results show that the new perfusion method proposed in this paper is feasible, and the effects of different liver perfusion methods and vascular geometric models on the dynamic characteristics of perfusion simulation are studied, and the theory of changing perfusion parameters to improve the quality of liver donor in clinical medical treatment is provided. Basis.

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R657.3

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