Development of time dependent biomechanical models for vascular tissue and implant design optimization

动脉粥样硬化性疾病是北美人死亡的主要原因之一。血管组织破裂是几种终末期心血管疾病的常见现象，包括可导致心肌梗死或心脏病发作的冠心病、可能导致出血的主动脉破裂和主动脉夹层。目前，医生正在使用简单的直径测量来估计疾病的严重程度。事实证明，这些措施并不准确。研究人员最近根据工程原理提出了新的标准，以更好地评估这些疾病。然而，即使是这些新指数也不能解释所有观察到的不良事件。例如，对于冠心病，新的标准不能解释大约30%的不良事件。因此，需要更好的标准来适应这些复杂的软组织，这些软组织表现出较大的变形，如橡胶。在过去的几年里，我研究了一种新的方法，基于对这种软组织中裂缝如何发生和进展的理解，以补充对组织破裂风险的评估。 该研究计划将使人们能够更好地了解这些软组织是如何在什么情况下以及何时发生故障的，这些故障可能会导致心脏病发作和出血等不良事件。获得的关于自然组织通常如何变形的新知识也将被用于设计下一代植入物，这种植入物也可以以同样的方式变形，以便更好地与身体互动。同样，这些信息也将被用于开发医学成像技术，以改进对组织状态的非侵入性评估。这些新的诊断和治疗战略应该会产生重要影响，因为大量人口受到这些医疗条件的影响。

Atherosclerotic diseases are amongst the principal causes of death in North America. The rupture of vascular tissue is a common phenomenon associated with several end-stage cardiovascular diseases including coronary disease which can cause myocardial infarction or heart attacks, aorta rupture and aorta dissection possibly leading to hemorrhage. Currently physicians are using simple diameter measurements to estimate the severity of the disease. These measures were proven to be imprecise. Researchers have recently proposed new criteria based on engineering principles to better assess these diseases. However, even these new indices cannot account for all observed adverse events. For example, for coronary disease the new criteria cannot account for about 30 % of the adverse events. There is thus a need for better criteria suited for these complex soft tissues that exhibit large deformations like rubber. I investigated, in the last years, a new approach based on the understanding of how cracks can happen and progress in such soft tissue for a complementary assessment of the risk of tissue rupture. The research program will allow to better understand how, under what conditions and when these soft tissues fail which can lead to adverse events like heart attacks and hemorrhage. The new knowledge acquired about how the native tissue normally deform will also be used to design the next generation of implants that can also deform in the same way in order to better interact with the body. Similarly, the information will also be used for developing medical imaging techniques for an improved non-invasive assessment of the state of the tissue. These new diagnostic and treatment strategies should have important impact as a large number of the population is affected by these medical conditions.