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RESEARCH PRODUCT

Biomechanics of human ascending aorta and aneurysm rupture risk assessment

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Ascending aortic aneurysms (AsAA) and aortic dissections are life-threatening cardiovascular diseases. The main criteria for determining surgical intervention of AsAA are the maximum diameter or the increasing annual rate of the aneurysm. The mortality of the untreated aortic dissection can be 21% to 74%, depending on the delay of hospital admission.Our study aims to characterize the biomechanical properties of the ascending aorta and propose a patient-specific approach to assess the risks of rupture. The purpose of this PhD work is multifold.On the one hand, biaxial tensile tests were performed on AsAA samples obtained from one hundred patients with surgery of AsAA. The impact on the different characteristics and risks was evaluated and cross-compared. We have shown that the risk factors of gender, age, diameter, and aortic valve disorders have a major impact on the stiffness of AsAA. On the other hand, eleven acute type A aortic dissection samples were collected. We have confirmed that the adventitia shows a significant stiffness than the intimomedial layer. Meanwhile, a rare case of AsAA associated with the quadricuspid aortic valve displays similar biomechanical properties to AsAA associated with the bicuspid aortic valve than with the tricuspid aortic valve. In order to make synthetic modeling from 3D printed aorta in 4D flow magnetic resonance imaging (MRI) study, three three-dimensional printable materials were tested to compare with an undilated aortic wall. The biomechanical properties of the 50 SH (shore stiffness) RGD450+TangoPlus is the most aorta-alike material.To conclude, from our result from one hundred patients, gender, age, diameter, and aortic valve disorders are the key to aortic stiffness.