Computational Tool to Assess Performance of the Aortic Trauma Stent-Grafts

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 DESCRIPTION (provided by applicant): Trauma is the number one cause of death among people younger than 44 years of age, and 33% of all traumatic deaths are attributed to aortic injuries within the thorax. Endovascular reconstruction of traumatized aorta using stent-grafts has evolved as a first line therapy for trauma patients, but these stent-grafts were designed for elderly patients with chronic degenerative arterial diseases and are less than ideal for the smaller and more angulated thoracic aortas of young patients. In addition, the increased patient activity and high cyclic loads imposed by more dynamic younger cardiovascular systems may push stent-graft materials to failure resulting in higher morbidity, mortality and expensive reinterventions over the course of a lifetime. The goal of this project is to create a computationa tool that can determine the optimal stent-graft characteristics for the aorta of trauma patients and the mechanical behavior of the implanted stent-grafts over the long-term. This tool will be able to measure the conformability of the stent-graft when implanted in the young thoracic aorta and the long-term durability of the stent-graft as determined by its capability to withstand high-cycle fatigue loads. We propose to accomplish this by three Specific Aims: In Aim 1 we will determine the morphometric features of the thoracic aorta in different young trauma populations (<20, 20-29, 30-45 years old) that are critical for stent-graft deployment using comprehensive 3D arterial reconstructions derived from thin-section CTA scans. In Aim 2 we will build in silico models of stent-grafts deployed in the aortas of young trauma patients using biaxial mechanical properties of thoracic aortic wall obtained from tissue donors of each age group, and experimentally determined mechanical properties of two stent-grafts (GORE C-Tag and Medtronic Valiant) that are currently approved for trauma. We will then use mathematical modeling to subject the stent-grafts to typical cyclic physiologic loads and assess the resulting stress-strain fields. In Aim 3 we will determine stent-graft conformability to the inner aortic wal when subjected to simulated in vivo loads, and long-term durability as determined by the capability of the device to withstand high-cycle fatigue loads assessed by using stress analysis and Goodman diagrams. These data will be acquired for each trauma population to identify specific characteristics of the devices that may enhance the acute and long-term outcomes of endovascular treatments in each trauma group. The proposed study will lay the foundation for in silico comparative effectiveness studies for existing and yet-to-be developed endovascular devices for young patient populations and will set new standards for analysis of trauma-oriented endovascular devices, facilitating the development of better stent-grafts. This work will promote integration of the applicant into the biomedical field and enhance her potential for independent research career while carving out an excellent niche for her to pursue independent funding in the future.