冠状动脉支架展开过程快速模拟计算及动物实验验证研究

Coronary artery disease is one of the most common diseases occurred in human cardiovascular system. In recent years, about 80% of the patients received the stent placement treatment. However, quite a few of these patients present in-stent restenosis after treatment, which induces recurrence of the arterial narrowing. The occurrence of this complication is closely related to the damage of the vessel wall by the expandable balloon and the stent as well as the changce of local hemodynamics. In this study, we apply computational mechanical analyses, investigating the hemodynamics and loading patterns over the vessel wall pre-and post-stent implantation, discussing possible mechanical factors that may induce in-stent restenosis, and evaluating the critical values of those mechanical indices, in order to, from the mechanical point of view, facilitate reasonable selection of stents, improve manipulation techniques, and thus reduce the occurrence of in-stent restenosis. On the other hand, through establishing experimental models of porcine coronary artery stenosis and applying ballon dilation as well as stent implantation, the accuracy of the abovementioned computational results will be investigated and validated. The other task of this project is to develop a fast-virtual stent deployment algorithm in order to facilitate medical doctors to predict the stent deployment configuration in real patients within a reasonable short period. The mechanical computations and the stent delopyment algorithm altogeher will provide infomation to help medical doctors evaluate whether the stent they selected is suitable for the specific patient and will be the main component to establish a medical management, evaluation and optimization platform for the stent treatment in coronary artery diseases.

冠心病是最常见的心血管疾病之一。近年来，约80%的患者接受人工支架置入术。但治疗后有相当比例的患者会发生支架内再狭窄，使血管再次阻塞。这种并发症的发生与球囊、支架对血管壁的损伤以及对局部血流的改变密切相关。本课题利用计算力学的模拟研究方法，对置入支架前后的冠脉血流以及血管壁面应力的变化进行分析，探讨引发支架内再狭窄的力学因素，并确定这些因素的临界值，为合理选用支架及操作技巧减少并发症提供力学参考。另一方面，通过制备猪的冠脉狭窄模型，模拟人的球囊扩张及支架置入术，验证力学计算的准确性。开发支架展开过程的快速模拟算法，以帮助医生在短时间内预测所选支架在病人体内的展开效果。为医生提供评价所选支架优劣的标准，并为建立针对冠脉支架治疗的医疗规划平台奠定基础。

本项目的主要研究内容包括冠脉经支架治疗后的血液动力学变化，冠脉支架展开过程快速模拟算法的开发，以及相关的动物实验验证三个主要部分。具体的研究工作包括：1.通过冠状动脉螺旋CT成像(CTA)和血管内超声（INVS）获得病人置入支架前、置入支架后（当天）以及随访时（6个月左右）的病灶部位医学影像； 2.对医学影像进行图像分割，重建病灶冠脉的三维模型，计算支架置入前后及随访时的血管内血流运动变化并分析壁面切应力的分布情况；3.支架展开过程快速模拟算法网格变形及接触模型的确定；4.制备猪的冠脉狭窄模型，进行球囊扩张及支架置入术，验证力学计算的准确性。项目执行期限仅有一年（2014.1-2014.12），目前，项目团队已完成：1.医学图像采集8例；2.三维模型重建及计算3例（包括支架置入前、置入当天和后期随访）；3.支架展开过程快速模拟算法中网格变形和接触模型的确定，以及算法在病人个体化三维模型（3例）中的应用；4.制备猪的冠脉狭窄模型1例。通过对这些案例的研究，在这一年中，项目团队初步建立了适用于冠脉狭窄支架治疗的支架展开过程快速模拟算法，分析了影响支架内再狭窄发生的可能的壁面切应力范围，并确定了动物实验的具体流程及预期目标。目前，前期研究成果已总结成文投往SCI期刊（已发表1篇，已接收1篇）及核心期刊（已接收2篇）。在后续研究中，我们将继续完善动物模型，完成对计算模拟结果的验证；进一步开展多病例模拟研究，确定评判支架置入合理与否的力学标准；并进一步改进支架展开过程的模拟算法，确保其适用性、准确性及稳定性。