BIOMECHANICAL EVALUATION OF ABDOMINAL AORTIC ANEURYSM

描述(摘自申请者摘要)：腹主动脉瘤 (AAA)是肾下大动脉的局灶性增大。如果不治疗，AAA 会逐渐扩大直到破裂；这一事件的死亡率为 90%，在最常见的死亡原因中排名第13位 我们。与外科手术修复AAA相关的是巨大的成本和风险 病人。因此，重要的是要确定何时破裂的风险 证明与手术相关的风险是合理的。能够可靠地评估 特定的AAA对破裂的易感性可以极大地改善 这些患者的临床管理，因为目前还没有这样的 可靠的评价标准。AAA破裂发生在机械应力 (即，内力)作用在动脉瘤壁上的能力超过了它的能力 承受这些应力(即墙体的破坏强度)。规模越大， 对于特定的AAA，墙体应力与墙体强度之比越大 破裂的可能性。因此，他们认为，以生物力学为基础的 方法“将有助于改进对心脏破裂倾向的评估 AAA根据患者的具体情况而定。在决定做手术之前 对于个别患者的干预，调查人员认为 外科医生应该知道两件事：作用于动脉瘤的机械应力 以及AAA墙的强度。他们最近取得了长足的进步， 这些末端。然而，为了改善他们对AAA墙体应力的估计 AAA壁的生物力学行为需要更加仔细和 严格定义。因此，第一个具体目标是提炼他们目前的 解释更现实的、各向异性生物力学的方法学 AAA的行为。他们之前的研究表明，有一个显著的，50 腹主动脉壁强度与非动脉瘤主动脉壁强度相比下降百分比。 然而，他们没有确定AAA壁强度的空间变异。 具体目标#2是开发一个基于统计的多因素模型 无创性评价腹主动脉壁强度的空间变异。具体目标#3 是为了产生破裂潜在指数(RPI)的空间变化 个人AAA级。RPI定义为局部作用的壁应力除以 局部墙体强度。当RPI接近值1.0时，AAA破裂 就在眼前。因此，临床医生可以检查RPI分布，以便 对特定的AAA进行评估。这种新颖的、创新的、基于计算机的 非侵入性方法将是一种重要而可靠的诊断工具 外科医生在决定选择性修复AAA时，极大地改善了 对患有这种疾病的患者的临床处理。

DESCRIPTION (Verbatim from Applicant's Abstract): Abdominal aortic aneurysm (AAA) is a focal enlargement of the infrarenal aorta. If left untreated, AAA will gradually expand until rupture; an event that carries a mortality rate of 90 percent and which is ranked as the 13th most common cause of death in the US. Associated with surgical repair of AAA are significant costs and risks to the patient. Thus, it is important to determine when the risk of rupture justifies the risks associated with surgery. The ability to reliably evaluate the susceptibility of a particular AAA to rupture could vastly improve the clinical management of these patients, as there presently exists no such reliable evaluation criterion. AAA rupture occurs when the mechanical stress (i.e., internal forces) acting on the aneurysm wall exceeds its ability to withstand these stresses (i.e., the wall's failure strength). The greater the wall stress to wall strength ratio for a particular AAA, the greater the likelihood of rupture. They therefore believe that a "biomechanics-based approach" would lead to an improved assessment of the propensity for rupture of AAA on a patient-specific basis. Before the decision is made for surgical intervention for an individual patient, the investigators believe that the surgeon should know two things: the mechanical stress acting on that aneurysm and the strength of the AAA wall. They have recently made great strides toward these ends. However, to improve their AAA wall stress estimates the biomechanical behavior of the AAA wall needs to be more carefully and rigorously defined. Therefore, Specific Aim #1 is to refine their current methodology to account for the more realistic, anisotropic biomechanical behavior of AAA. They previously showed that there occurs a significant, 50 percent decrease in strength of the AAA wall versus nonaneurysmal aorta. However, they did not determine spatial variation of AAA wall strength. Specific Aim #2 is to develop a statistically based, multifactorial model to noninvasively estimate spatial variation of AAA wall strength. Specific Aim #3 is to generate the spatial variation of the rupture potential index (RPI) for individual AAA. The RPI is defined as the locally acting wall stress divided by the local wall strength. As the RPI nears a value of 1.0, AAA rupture is imminent. The clinician may therefore inspect the RPI distribution in order to make an evaluation for a particular AAA. This novel, innovative, computer-based noninvasive method would be an important and reliable diagnostic tool to guide the surgeon in decisions for elective repair of AAA, greatly improving the clinical management for those afflicted with this disease.