FLOW EFFECTS ON VASCULAR STENT FAILURE

血流对血管支架失效的影响

• 批准号: 6579928
• 负责人: JAMES E MOORE
• 金额: $ 7.38万
• 依托单位: FLORIDA INTERNATIONAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6579928
• 关键词: biomechanics; blood vessel prosthesis; computer simulation; confocal scanning microscopy; fluid flow; human subject; human tissue; mathematical model; mechanical stress; model design /development; platelets

Vascular stents are being used clinically in increasing numbers for a variety of vascular disorders, but thrombosis and neointimal hyperplasia continue to compromise the potential utility of these devices. The research outlined in this proposal is based on the hypothesis that fluid mechanical phenomenon are, in part, responsible for clinical failures of vascular stents. The overall goals of this research are to determine how fluid mechanics may be related to platelet deposition on stents in the acute implementation stage, and how stent design can be changed to minimize the risk of flow-related restonosis. The specific aims of the proposed research are: Determine the amount of overall platelet deposition in cylindrical compliant stented artery models using an in vitro flow apparatus with human blood as the working fluid. Platelet deposition will be quantified by the present of radioactively labeled platelets on the tube wall. Three different stent designs (two commercially available designs and one prototype design) will be studied. Determine the localization of platelet deposition in a flate-plate stented artery model using fluorescent labeled platelets and confocal microscopy. The same three stent designs will be studied. Quantify the degree of flow separation and stagnation in the three different stent designs using computational fluid dynamics (CFD) techniques. Since the presence of pulsatile flow burs the definition of flow separation, a separation parameter has been defined and will be varied parametrically. Areas of flow stagnation will be identified by the presence of persistent low all shear rates. The extent of flow separation and stagnation will be statistically compared with the platelet deposition data. Further elucidate the role of flow patterns in platelet deposition in stents by performing experimental and computational particle tracking. Particle residence times will be quantified near the struts of the same three stent designs and statistically compared with the platelet deposition data. Stimulate the progression of neointimal development in the CFD flow simulations by "filling in" areas of flow separation. The separation parameter mention above will be adapted to define areas of pulsatile flow separation. The resulting tissue growth patterns will be compared with available in vivo data on neointimal development patterns. This work is expected to provide unique information on the mechanical aspects of stenting. This information will aid in developing the next generation of stent design in which arterial mechanics are a prime consideration.

临床上越来越多的血管支架被用于治疗各种血管疾病，但血栓形成和新生内膜增生继续损害这些装置的潜在用途。这项建议中概述的研究是基于这样一种假设，即流体机械现象是血管支架临床失败的部分原因。这项研究的总体目标是确定流体力学如何与急性实施阶段支架上的血小板沉积有关，以及如何改变支架设计以将血流相关再狭窄的风险降至最低。这项研究的具体目标是：使用体外流动装置，以人血为工作液，测定圆柱形顺应性支架动脉模型中的总体血小板沉积量。血小板沉积将通过管壁上放射性标记的血小板的存在来量化。将研究三种不同的支架设计(两种商用设计和一种原型设计)。用荧光标记的血小板和共聚焦显微镜确定平板支架动脉模型中血小板沉积的位置。同样的三种支架设计将被研究。使用计算流体动力学(CFD)技术量化三种不同支架设计中的流动分离和停滞程度。由于脉动流的存在破坏了流动分离的定义，因此已经定义了分离参数，并将随参数变化。流动停滞区将通过所有剪切率持续较低的存在来识别。血流分离和停滞的程度将与血小板沉积数据进行统计比较。通过进行实验和计算颗粒跟踪，进一步阐明流动模式在支架内血小板沉积中的作用。颗粒滞留时间将在相同三种支架设计的支柱附近进行量化，并与血小板沉积数据进行统计比较。在CFD流动模拟中，通过“填充”流动分离区域来刺激新生内膜的发展。上述分离参数将适用于确定脉动流动分离的区域。由此产生的组织生长模式将与体内关于新生内膜发育模式的现有数据进行比较。这项工作有望为支架置入术的机械方面提供独特的信息。这些信息将有助于开发下一代支架设计，其中动脉力学是主要考虑因素。