title: Constitutive modeling of ascending thoracic aortic aneurysms using microstructural parameters.
abstract: Ascending thoracic aortic aneurysm (ATAA) has been associated with diminished biomechanical strength and disruption in the collagen fiber microarchitecture. Additionally, the congenital bicuspid aortic valve (BAV) leads to a distinct extracellular matrix structure that may be related to ATAA development at an earlier age than degenerative aneurysms arising in patients with the morphological normal tricuspid aortic valve (TAV). The purpose of this study was to model the fiber-reinforced mechanical response of ATAA specimens from patients with either BAV or TAV. This was achieved by combining image-analysis derived parameters of collagen fiber dispersion and alignment with tensile testing data. Then, numerical simulations were performed to assess the role of anisotropic constitutive formulation on the wall stress distribution of aneurysmal aorta. Results indicate that both BAV ATAA and TAV ATAA have altered collagen fiber architecture in the medial plane of experimentally-dissected aortic tissues when compared to normal ascending aortic specimens. The study findings highlight that differences in the collagen fiber distribution mostly influences the resulting wall stress distribution rather than the peak stress. We conclude that fiber-reinforced constitutive modeling that takes into account the collagen fiber defect inherent to the aneurysmal ascending aorta is paramount for accurate finite element predictions and ultimately for biomechanical-based indicators to reliably distinguish the more from the less 'malignant' ATAAs.
authors.affiliation: Fondazione Ri.MED, Via Bandiera n.11, 90133 Palermo, Italy ; Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy. Electronic address: spasta@fondazionerimed.com.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pasta
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; Center for Thoracic Aortic Disease, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Phillippi
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15219, USA.
authors.forename: Alkiviadis
authors.initials: A
authors.lastname: Tsamis
authors.affiliation: Fondazione Ri.MED, Via Bandiera n.11, 90133 Palermo, Italy ; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA; DICGIM, Universitá di Palermo, Palermo 90128, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: D'Amore
authors.affiliation: Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Raffa
authors.affiliation: Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Pilato
authors.affiliation: Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Scardulla
authors.affiliation: Department of Cell Biology and Physiology, Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Watkins
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Wagner
authors.affiliation: Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; Center for Thoracic Aortic Disease, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Gleason
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; Center for Thoracic Aortic Disease, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Vorp
mesh_terms: D001011:Aorta / Q000378:metabolism / Q000473:pathology*; D017545:Aortic Aneurysm, Thoracic / Q000378:metabolism / Q000473:pathology*; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D020342:Finite Element Analysis; D006801:Humans; D055595:Mechanical Phenomena; D008954:Models, Biological; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D003094:Collagen
keywords: Aortic aneurysm; Aortic failure; Bicuspid aortic valve; Extracellular matrix; Finite element