Investigation of the effects of endovascular prostheses on cardiovascular fluid-structure interactions

使用血管内支架治疗动脉疾病是一个迅速崛起的重要领域，因为它是治疗闭塞、退行性疾病和动脉瘤疾病的首选方法。支架被插入血管以重建血管直径，无论是为了重新扩张梗阻(狭窄)还是为了遏制通过血管扩大的血流(见图)。尽管有这些不同的临床要求，但所有设备都必须从根本上遵守最主要的机械原理，即适当地产生径向力，以便更好地接近血管壁，以实现预期的临床结果。如果支架施加的力太大或太小，支架的通畅性可能会受到影响。许多临床问题是由支架区域和天然血管之间发生的顺应性不匹配引起的。与放置在主动脉中的支架的顺应性不匹配会导致过度扩张、血管结疤和波反射增加，从而导致血压升高。血流速度模式和壁切应力的变化也可归因于顺应性不匹配，并影响内皮反应、支架移位或血液渗漏。尽管这些担忧很重要，但作用于血管内支架的作用力还没有得到很好的识别或定义，文献中几乎没有可用的信息。我提出的研究目的是使用实验和数值模型来更好地了解血管内支架的负荷，以及它们如何影响血管/支架的顺应性、波传播、波反射、壁切应力、压力和流量。

The use of endovascular stents for management of arterial disease is a rapidly emerging area of importance as it is the preferred choice in the management of occlusive, degenerative and aneurismal disease. A stent is inserted into a vessel to re-establish the vessel diameter, whether that is for re-expansion of an obstruction (stenosis) or to contain the flow through a vessel enlargement (aneurysm - see Figure). Despite these differing clinical requirements, all devices must fundamentally adhere to the overarching mechanical principle of appropriate generation of radial force for good approximation of the vessel wall in order that the desired clinical outcome is achieved. If the stent applies too much or too little force the patency of the stent can be compromised. Many clinical issues arise from the compliance mismatch that occurs between the stented region and the native vessel. Compliance mismatches from stents placed in the aorta can produce over dilation, vessel scarring and increased wave reflections resulting in higher blood pressure. Changes in blood flow velocity patterns and wall shear stress are also attributable to compliance mismatch and influence endothelial response, stent migration or blood leakage. In spite of the importance of these concerns, the forces acting on endovascular stents have not been well identified or defined, with little information available in the literature. The goal of my proposed research is to use experimental and numerical models to better understand the loading of endovascular stents, and how they affect vessel/stent compliance, wave propagation, wave reflection, wall shear stress, pressure and flow.