基于个体化冠脉的球囊-支架系统数值模拟

发布时间：2018-05-13 13:05

本文选题：冠心病 + 个体化　；参考：《首都医科大学》2016年硕士论文

【摘要】：冠心病是指冠状动脉粥样硬化使管腔发生堵塞以及冠状动脉功能性的改变,导致心肌缺血、缺氧而引起的心脏病,亦称为缺血性心脏病。冠心病严重威胁着人类的健康,其预防、诊断和治疗一直是临床研究中一项迫切需要解决的重大课题。支架植入术是治疗冠心病的一种有效手段,近年来得到了广泛应用。其过程是将压握在球囊导管的支架输送到血管病变部位,通过施压膨胀球囊使支架扩张变形以达到支撑血管的目的。目前,支架植入手术方案如支架尺寸、置入方案的选取等主要依靠造影二维显像和临床经验,缺乏必要的理论依据,也无法直接获取支架后冠脉的管腔几何形变及内部钢梁分布与贴壁情况,预估病人的治疗效果。而且人体存在个体差异性,不合理的支架手术方案可能引发术后并发症如支架后再狭窄等。本论文立足于当前冠脉支架植入手术治疗冠心病的现状,期望建立一种基于个体化冠脉的球囊-支架系统模型,能够更加真实的反映临床中支架在狭窄冠脉段扩张及回弹服役的过程,从而更直观地了解支架植入引起的管腔几何形变、支架与血管的应力应变情况以及支架钢梁的分布与贴壁情况等,为个性化的支架植入手术方案和疗效预测提供一定的指导。论文的主要工作包括:针对球囊-支架系统扩张和回弹模拟中的球囊选择,我们研究了不同球囊褶皱模型对支架扩张和回弹过程的影响。结合制造商提供的压力-直径顺应性曲线验证模拟的合理性,并引入“狗骨头”率(DB)、轴向缩短率(LR)及径向回弹率(RR)评估球囊-支架系统模拟结果的优劣。结果表明,球囊的褶皱形态影响着支架的扩张和回弹,无褶球囊-支架系统的模拟效果最差,六褶锥形末端球囊-支架系统的模拟结果最符合制造商的数据,支架扩张更加均匀,且DB、LR和RR都较低。因此,在有限元模拟中,为了更真实的模拟支架的扩张和回弹,球囊的褶皱和锥形末端的几何特征不可忽略。在论文的第二大部分(第三章),我们根据患者的CT血管造影(CTA)影像重建右冠状动脉模型,采用第一部分讨论的六褶锥形末端球囊,进行基于个体化冠脉的球囊-支架系统共同扩张和回弹的耦合模拟,对有限元模拟的准静态条件及临床一致性进行了评估,并分析了管腔几何支架前后的形变及支架扩张最大时刻和回弹服役时刻血管和支架的应力应变分布,最后对支架的定位情况进行了研究。评估结果发现,计算模拟结果与临床造影显像具有良好的一致性。支架的植入使血管发生了一定程度的抻直形变,同时也很大程度上改变了血管的管腔直径和管腔面积。血管的最大主应力分布主要集中在斑块区域,在支架最大扩张程度下的应力值达到了血管的极限应力,可能有破裂的风险。支架受到的Mises应力最值出现在支撑体的拐弯处以及花冠间的连接处。在服役的最终时刻,我们还发现支架近端附近出现了接触不良现象,这可能与回弹不完全和弯曲的几何构造相关。
[Abstract]:Coronary artery disease is a kind of coronary atherosclerosis that causes the obstruction of the cavity and the function of coronary artery, which leads to myocardial ischemia and hypoxia. It is also called ischemic heart disease. Coronary heart disease is a serious threat to human health. The prevention, diagnosis and treatment of coronary artery disease is an important lesson in clinical research. Stent implantation is an effective method for the treatment of coronary heart disease. It has been widely used in recent years. The process is to carry the stent in the balloon catheter to the site of vascular lesion, and to expand the stent by pressure expansion balloon to achieve the purpose of supporting the blood vessel. The selection is mainly dependent on the two-dimensional imaging and clinical experience, lack of the necessary theoretical basis, and can not directly obtain the geometric deformation of the cavities of the stent and the distribution of the internal steel beam and the adherence of the internal steel, and predict the treatment effect of the patients. Moreover, there are individual differences in the human body. The unreasonable stent operation may lead to postoperative complications. This paper, based on the current status of coronary stent implantation in the treatment of coronary heart disease, expects to establish a balloon stent system based on individualized coronary artery, which can more truly reflect the process of stent expansion and resilience in narrow coronary segments, thus more intuitively understanding of stent implantation. The geometric deformation of the cavity, the stress and strain of the stent and blood vessel, the distribution and the attachment of the support steel beam provide some guidance for the individualized stent implantation and the prediction of the effect. The main work of this paper includes: We studied the different spheres for the balloon stent system expansion and the selection of the balloon in the rebound simulation. The effect of the capsule fold model on the expansion and springback of the scaffold. Combined with the pressure diameter compliance curve provided by the manufacturer to verify the rationality of the simulation, and the introduction of the "dog bone" rate (DB), the axial shortening rate (LR) and radial rebound rate (RR) to evaluate the simulation results of the balloon stent system. The results show that the fold shape of the balloon affects the support. The expansion and rebound of the frame, the least simulated effect of the folds of the balloon stent system, the simulation results of the six fold tapered end balloon stent system most conform to the manufacturer's data, the stent expansion is more uniform, and the DB, LR and RR are lower. Therefore, in the finite element simulation, the folds and cones of the balloon are in the form of more real simulation of the expansion and rebound of the scaffold. The geometric features of the end can not be ignored. In the second part of the paper (third chapter), we reconstruct the right coronary artery model based on the CT angiography (CTA) image of the patient, and use the six fold tapered terminal balloon discussed in the first part to simulate the joint expansion and rebound of the balloon support system based on the individual coronary artery, and to the finite element. The quasi static condition and clinical consistency of the simulation were evaluated. The deformation of the stent, the maximum time of stent expansion and the stress and strain distribution of the stent were analyzed. Finally, the position of the stent was studied. The results were presented, and the results of calculation and clinical imaging were calculated. Good consistency. The implantation of the stent causes a certain degree of straightening of the blood vessel, and it also greatly changes the diameter of the lumen and the cavity area of the vessel. The distribution of the maximum principal stress in the blood vessel is mainly concentrated in the patch area. The stress value under the maximum expansion of the stent has reached the ultimate stress of the blood vessel, and may have broken down. Risk. The Mises stress of the scaffold is most valued at the bend of the support and the junction between the corolla. At the end of the service, we also found that there was a bad contact near the proximal end of the support, which may be related to the incomplete and curved geometry of the springback.

【学位授予单位】：首都医科大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R541.4

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