title: Local mechanical properties of human ascending thoracic aneurysms.
abstract: Ascending thoracic aortic aneurysms (ATAAs) are focal, asymmetric dilatations of the aortic wall which are prone to rupture. To identify potential rupture locations in advance, it is necessary to consider the inhomogeneity of the ATAA at the millimeter scale. Towards this end, we have developed a combined experimental and computational approach using bulge inflation tests, digital image correlation (DIC), and an inverse membrane approach to characterize the pointwise stress, strain, and hyperelastic properties of the ATAA. Using this approach, the pointwise hyperelastic material properties were identified on 10 human ATAA samples collected from patients undergoing elective surgery to replace their ATAAs with a graft. Our method was able to capture the varying levels of heterogeneity in the ATAA from regional to local. It was shown for the first time that the material properties in the ATAA are unmistakably heterogeneous at length scales between 1mm and 1cm, which are length scales where vascular tissue is typically treated as homogeneous. The distributions of the material properties for each patient were also examined to study the inter- and intra-patient variability. Large inter-subject variability was observed in the elastic properties.
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, SAINBIOSE, F-42023 St. Étienne, France; INSERM, U1059, F-42000 Saint Etienne, France; Université de Lyon, SAINBIOSE, F-42000 Saint Etienne, France; University of Southampton, Engineering Materials, SO17 1BJ, Southampton, UK. Electronic address: frances.davis@emse.fr.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Davis
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, United States. Electronic address: yuanming-luo@uiowa.edu.
authors.forename: Yuanming
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, SAINBIOSE, F-42023 St. Étienne, France; INSERM, U1059, F-42000 Saint Etienne, France; Université de Lyon, SAINBIOSE, F-42000 Saint Etienne, France. Electronic address: avril@emse.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Avril
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, SAINBIOSE, F-42023 St. Étienne, France; INSERM, U1059, F-42000 Saint Etienne, France; Université de Lyon, SAINBIOSE, F-42000 Saint Etienne, France; Cardiovascular Surgery Service, CHU de Saint-Etienne, F-42055 St. Étienne CEDEX 2, France. Electronic address: ambroise.duprey@emse.fr.
authors.forename: Ambroise
authors.initials: A
authors.lastname: Duprey
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, United States. Electronic address: jia-lu@uiowa.edu.
authors.forename: Jia
authors.initials: J
authors.lastname: Lu
mesh_terms: D001011:Aorta; D017545:Aortic Aneurysm, Thoracic / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D006801:Humans; D008955:Models, Cardiovascular; D012421:Rupture; D013314:Stress, Mechanical
keywords: Distribution of material properties; Heterogeneous material properties; Inter-patient variation; Intra-patient variation; Inverse elastostatic analysis; Thoracic aneurysm