两种血管通路中血流特性及其对管壁影响的数值模拟研究

发布时间：2018-11-03 07:11

【摘要】：深入理解血液流动的特性及血管的响应对于相关治疗方案的改进和选取至关重要。由于血液流动的复杂性及活体实验的困难,目前在这方面的研究成果尚不能满足临床需求。本文结合动静脉内瘘和深静脉留置导管这两种常见的手术在此方面开展了数值模拟研究。在肾功能衰竭晚期,接受血液透析治疗是患者维持生存的重要手段,而良好的血管通路是血液透析治疗成功的关键。一般来说,自体动静脉内瘘是最佳的血管通道,但动静脉内瘘改变了原来的血液流动,可能会引起血管壁内膜增生。本文采用有限体积法,并考虑了血液的非牛顿流体性质以及血流的非定常性,在血管壁刚性无滑移的假设下,对自体动静脉内瘘对血流的影响进行了数值模拟。模拟结果表明:内瘘部分出现了一个比较复杂的涡流,导致内瘘附近的静脉壁面剪切力的最小值很小;距内瘘越近,截面上的壁面剪切力分布的不均匀程度越大,血管的稳定性越低,这很可能是导致动静脉瘘口吻合处静脉内膜增生的一个重要原因。某些高龄或心功能不全的患者,因其血管的条件较差,不能建立动静脉内瘘或者患者不能耐受内瘘。对于此类患者可考虑采用长期深静脉留置导管,然而血流不畅或内膜增生同样可能导致导管功能失效。本文对置入导管的静脉段的血流进行了数值模拟,结果表明:在导管侧孔处,血管壁上的壁面剪切力的分布不均匀。结合其他学者的研究成果,可推测剪切力的不均匀分布对血管内膜增生有重要影响。
[Abstract]:An in-depth understanding of the characteristics of blood flow and the response of blood vessels is essential to the improvement and selection of treatment protocols. Due to the complexity of blood flow and the difficulty of in vivo experiments, the current research results in this field can not meet the clinical needs. Combined with arteriovenous fistula and deep vein indwelling catheter, numerical simulation was carried out in this paper. In the late stage of renal failure, hemodialysis is an important means to maintain the survival of patients, and good vascular access is the key to successful hemodialysis treatment. In general, autogenous arteriovenous fistula is the best vascular channel, but arteriovenous fistula changes the original blood flow and may cause intimal hyperplasia. In this paper, the influence of autogenous arteriovenous fistula on blood flow was numerically simulated under the assumption of rigid vessel wall and no slip, taking into account the non-Newtonian fluid properties of blood and the unsteady flow of blood flow by using the finite volume method. The simulation results show that there is a complicated eddy current in the internal fistula which results in the minimal shear stress of the venous wall near the internal fistula. The closer to the internal fistula, the greater the uneven distribution of shear force on the wall of the section, and the lower the stability of the blood vessel, which may be an important reason for the intimal hyperplasia of the vein at the anastomosing position of the arteriovenous fistula. Some patients with advanced age or heart failure can not establish arteriovenous fistula or can not tolerate internal fistula because of their poor vascular conditions. Long-term deep venous catheterization may be considered for such patients, but poor blood flow or intimal hyperplasia may also lead to catheter failure. In this paper, the blood flow in the vein segment of the catheter is simulated. The results show that the shear force on the wall of the vessel wall is not evenly distributed at the lateral orifice of the catheter. Combined with the research results of other scholars, it can be inferred that the uneven distribution of shear stress plays an important role in intimal hyperplasia.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R692.5;O35

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