Aortic Wall Microarchitecture and Cyclic Strain

描述（由申请人提供）： 人主动脉易受动脉粥样硬化斑块沉积和动脉瘤扩大的影响。虽然具体的因果机制尚不清楚，但生物力学因素被认为起着重要作用，特别是在胸主动脉和腹主动脉对这些退行性变化的不同易感性方面。我们开发了一种无创磁共振方法来量化体内主动脉壁的生物力学，发现主动脉壁的运动和应变在主动脉周围变化，主动脉结构有显着的局部变化。这与偏心斑块定位和局灶性动脉瘤形成的临床观察结果一致。此外，主动脉生物力学受到植入的血管内器械（如支架和覆膜支架）的影响，这些器械用于治疗主动脉闭塞性疾病和动脉瘤，长期后果未知。 在此期间，我们将涉及不同的主动脉应变模式在体内测量的三维微结构的正常猪腹主动脉。然后，我们将在实验动物体内植入血管内主动脉支架和覆膜支架，以改变主动脉壁的生物力学。我们将评估对体内主动脉壁生物力学的急性和慢性影响以及主动脉微观结构的长期变化。我们将利用相同的体内磁共振成像技术来评估人体主动脉壁运动和周期性应变，并量化主动脉周长和沿着长度的差异。我们将研究年轻和老年健康志愿者，以辨别年龄和性别相关的主动脉壁生物力学差异。这些数据将为我们理解与生物力学应变相关的主动脉结构和组成提供有价值的见解，并将提供一种评估使用植入式主动脉器械进行介入治疗对主动脉壁影响的方法。此外，这些研究将提供一个框架，以了解影响人类主动脉的正常年龄相关性和退行性变化。最后，它将提供一个定量的基础上，主动脉磁共振成像在更大的人体临床试验中的应用，涉及患者的动脉瘤或闭塞性疾病的主动脉，之前和之后的血管内治疗。

DESCRIPTION (provided by applicant): The human aorta is susceptible to both atherosclerotic plaque deposition and aneurysmal enlargement. While the specific causal mechanisms are unclear, biomechanical factors are thought to play an important role, particularly in the differing susceptibility of the thoracic and abdominal aorta to these degenerative changes. We developed a non-invasive magnetic resonance method to quantify aortic wall biomechanics in vivo and found that aortic wall motion and strain vary around the aortic circumference with significant local variation in aortic structure. This is consistent with clinical observations of eccentric plaque localization and focal aneurysm formation. Furthermore, aortic biomechanics are impacted by implanted endovascular devices such as stents and stent grafts which are used to treat occlusive disease and aneurysms of the aorta with unknown long term consequences. During this grant, we will relate varying aortic strain patterns measured in vivo to the 3-dimensional microarchitecture of normal porcine aortas. We will then implant endovascular aortic stents and stent grafts in experimental animals to modify aortic wall biomechanics. We will assess the acute and chronic impact on in vivo aortic wall biomechanics and long-term changes in aortic microstructure. We will utilize the same in vivo magnetic resonance imaging technique to assess aortic wall motion and cyclic strain in humans and quantitate the differences about the circumference and along the length of the aorta. We will study both young and elderly healthy volunteers in order to discern age and gender related differences in aortic wall biomechanics. These data will provide valuable insights into our understanding of the structure and compostition of the aorta in relation to biomechanical strain and will provide a means of assessing the impact on the aortic wall of interventional treatments using implanted aortic devices. Further, these studies will provide a framework to understand normal age-related and degenerative changes affecting the human aorta. Finally, it will provide a quantitative basis for application of aortic magnetic resonance imaging in larger human clinical trials involving patients with aneurysmal or occlusive disease of the aorta, both before and after endovascular treatment.