Glenn手术血流动力学几何多尺度数值模拟及其PIV实验研究

发布时间：2018-12-18 21:56

【摘要】：Glenn手术是单心室缺陷综合征姑息性手术Fontan手术的第二步。Glenn手术是将上腔静脉与肺动脉进行端侧吻合,上腔静脉血直接流入左右肺动脉进入肺部,进行血氧交换,而不与肺静脉的动脉血混合,从而减轻紫绀症状。血流动力学因素是影响心血管疾病手术后恢复的重要因素。单心室病人常伴随有血管发育不良等并发症,其中最常见的是肺动脉狭窄。不同的肺动脉狭窄程度会造成不同的血流情况,影响病人术后左右肺的分流量和能量损耗等血管发育的生理需求,增加单心室负荷,在血流动力学角度上也会造成不良的血流动力学因素,可能会影响手术成功率及手术长期有效性。目前临床上实施手术主要依据二维医学图像和临床医生的手术经验,缺乏手术前血流动力学理论指导。而基于血流动力学理论,运用几何多尺度方法实现手术规划,可得到临床上关心的血流动力学参数及指标,给临床提供一定的参考。本研究研究内容包括:1、基于单心室病人的二维CT图像,重建单心室病人血管图像,并通过虚拟手术,构建肺动脉不同狭窄的Glenn手术三维模型,以分析比较不同的肺动脉狭窄对Glenn术后血流动力学的影响;2、建立单心室病人血液循环系统的集中参数模型,通过不断调试和试验,确定集中参数模型各个元件的参数;3、将上述三维模型代替到集中参数模型相应的部分,进行几何多尺度的耦合,通过对四种不同肺动脉狭窄程度的Glenn术后模型进行仿真,从血流动力学角度对比不同狭窄程度对病人术后发展的影响;4、制作Glenn手术透明模型,在数值模拟基础上初步进行几组稳态PIV试验。研究结果表明:病人不同的血管发育情况对单心室病人Glenn手术后的血管恢复有重要的影响。对于伴随单边肺动脉狭窄的单心室病人,随着狭窄程度的增加,研究结果呈现了左肺动脉逐渐减小的分流率和逐渐增高的能量损耗,并当狭窄为75%或高于75%时,左肺动脉的分流急剧下降,能量损耗也远远高于狭窄程度较小的模型,且分布较大面积的高OSI区域。这些血流动力学参数均表明在同一Glenn手术方式下,左肺动脉狭窄程度为75%或高于75%时,狭窄对血管壁将产生不良的血流动力学影响。本研究对单心室病人在单边肺动脉不同程度狭窄的情况下进行虚拟Glenn手术,数值模拟中所用几何多尺度方法能够准确为三维模型的数值计算提供近生理的边界条件,在血流动力学角度上研究肺动脉不同狭窄对Glenn手术术后恢复的影响,并运用粒子图像测速(Particle Image Velocimetry,PIV)技术对Glenn手术进行数值模拟研究的验证。
[Abstract]:Glenn operation is the second step of Fontan operation in patients with single ventricular defect syndrome. Glenn procedure is to anastomose the superior vena cava with the pulmonary artery end-to-side, the blood of the superior vena cava flows directly into the left and right pulmonary arteries to enter the lung for blood oxygen exchange. And does not mix with the arterial blood of pulmonary vein, thereby alleviate cyanosis symptom. Hemodynamic factors play an important role in postoperative recovery of cardiovascular diseases. Single ventricle patients often have complications such as vascular dysplasia, the most common of which is pulmonary artery stenosis. Different degree of pulmonary artery stenosis will cause different blood flow, which will affect the physiological requirements of left and right lung flow and energy loss, and increase the single ventricular load. Hemodynamic factors may affect the success rate and long-term effectiveness of the operation. At present, the clinical practice of surgery is mainly based on two-dimensional medical images and clinicians' operation experience, lack of theoretical guidance of hemodynamics before surgery. Based on the theory of hemodynamics and the geometric multi-scale method, the parameters and indexes of hemodynamics concerned in clinic can be obtained, which can provide a certain reference for clinical practice. The main contents of this study are as follows: 1. Based on two-dimensional CT images of patients with single ventricle, the vascular images of patients with single ventricle were reconstructed, and a three-dimensional model of Glenn operation with different stenosis of pulmonary artery was constructed by virtual surgery. To compare the effect of pulmonary artery stenosis on hemodynamics after Glenn. (2) to establish the centralized parameter model of blood circulation system of single ventricular patients, and to determine the parameters of each component of the centralized parameter model through continuous debugging and testing. 3. The above 3D model is replaced by the corresponding part of the lumped parameter model, and the geometric multi-scale coupling is carried out. Four kinds of Glenn postoperative models with different degree of pulmonary artery stenosis are simulated. The effects of different degree of stenosis on postoperative development were compared from hemodynamic point of view. 4. The transparent model of Glenn operation was made and several steady state PIV tests were carried out on the basis of numerical simulation. The results show that different vascular development in patients with single ventricle plays an important role in the recovery of blood vessels after Glenn surgery. For patients with unilateral pulmonary artery stenosis, the results of the study showed a decreasing shunt rate and increasing energy loss of the left pulmonary artery as the degree of stenosis increased, and when the stenosis was 75% or higher, The shunt of the left pulmonary artery decreased sharply and the energy loss was much higher than that of the model with less stenosis and the large area of high OSI was also found. These hemodynamic parameters indicated that when the stenosis degree of left pulmonary artery was 75% or higher than 75% in the same Glenn procedure, the stenosis would have a bad hemodynamic effect on the vascular wall. In this study, virtual Glenn surgery was performed on single-ventricular patients with unilateral pulmonary artery stenosis of varying degrees. The geometric multi-scale method used in the numerical simulation can provide the near physiological boundary conditions for the numerical calculation of the three-dimensional model. The effect of different stenosis of pulmonary artery on postoperative recovery of Glenn was studied in terms of hemodynamics. The particle image velocimetry (Particle Image Velocimetry,PIV) technique was used to verify the numerical simulation of Glenn operation.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R654.2

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