title: Human thoracic and abdominal aortic aneurysmal tissues: Damage experiments, statistical analysis and constitutive modeling.
abstract: Development of aortic aneurysms includes significant morphological changes within the tissue: collagen content increases, elastin content reduces and smooth muscle cells degenerate. We seek to quantify the impact of these changes on the passive mechanical response of aneurysms in the supra-physiological loading range via mechanical testing and constitutive modeling. We perform uniaxial extension tests on circumferentially and axially oriented strips from five thoracic (65.6 years ± 13.4, mean ± SD) and eight abdominal (63.9 years ± 11.4) aortic fusiform aneurysms to investigate both continuous and discontinuous softening during supra-physiological loading. We determine the significance of the differences between the fitted model parameters: diseased thoracic versus abdominal tissues, and healthy (Weisbecker et al., J. Mech. Behav. Biomed. Mater. 12, 93-106, 2012) versus diseased tissues. We also test correlations among these parameters and age, Body Mass Index (BMI) and preoperative aneurysm diameter, and investigate histological cuts. Tissue response is anisotropic for all tests and the anisotropic pseudo-elastic damage model fits the data well for both primary loading and discontinuous softening which we interpret as damage. We found statistically relevant differences between model parameters fitted to diseased thoracic versus abdominal tissues, as well as between those fitted to healthy versus diseased tissues. Only BMI correlated with fitted model parameters in abdominal aortic aneurysmal tissues.
authors.affiliation: Departments of Mechanical Engineering, Biomedical Engineering and Mathematics, University of Connecticut, CT, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Pierce
authors.affiliation: Institute of Biomechanics, Graz University of Technology, Graz, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Maier
authors.affiliation: Institute of Biomechanics, Graz University of Technology, Graz, Austria.
authors.forename: Hannah
authors.initials: H
authors.lastname: Weisbecker
authors.affiliation: Institute of Pathology, Medical University Graz, Graz, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Viertler
authors.affiliation: Experimental Cardiac Surgery, Faculty of Medicine, UZ Leuven, Leuven, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Verbrugghe
authors.affiliation: Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Famaey
authors.affiliation: Vascular Surgery, Faculty of Medicine, UZ Leuven, Leuven, Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Fourneau
authors.affiliation: Experimental Cardiac Surgery, Faculty of Medicine, UZ Leuven, Leuven, Belgium.
authors.forename: Paul
authors.initials: P
authors.lastname: Herijgers
authors.affiliation: Institute of Biomechanics, Graz University of Technology, Graz, Austria. Electronic address: holzapfel@tugraz.at.
authors.forename: Gerhard A
authors.initials: GA
authors.lastname: Holzapfel
mesh_terms: D000367:Age Factors; D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000473:pathology* / Q000503:physiopathology; D017545:Aortic Aneurysm, Thoracic / Q000473:pathology* / Q000503:physiopathology; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013223:Statistics as Topic
keywords: Aortic aneurysm; Constitutive modeling; Damage modeling; Human aorta; Supra-physiological loading