title: The fiber orientation in the coronary arterial wall at physiological loading evaluated with a two-fiber constitutive model.
abstract: A patient-specific mechanical description of the coronary arterial wall is indispensable for individualized diagnosis and treatment of coronary artery disease. A way to determine the artery's mechanical properties is to fit the parameters of a constitutive model to patient-specific experimental data. Clinical data, however, essentially lack information about the stress-free geometry of an artery, which is necessary for constitutive modeling. In previous research, it has been shown that a way to circumvent this problem is to impose extra modeling constraints on the parameter estimation procedure. In this study, we propose a new modeling constraint concerning the in-situ fiber orientation (β                         (phys)). β                         (phys), which is a major contributor to the arterial stress-strain behavior, was determined for porcine and human coronary arteries using a mixed numerical-experimental method. The in-situ situation was mimicked using in-vitro experiments at a physiological axial pre-stretch, in which pressure-radius and pressure-axial force were measured. A single-layered, hyperelastic, thick-walled, two-fiber material model was accurately fitted to the experimental data, enabling the computation of stress, strain, and fiber orientation. β                         (phys) was found to be almost equal for all vessels measured (36.4 ± 0.3)°, which theoretically can be explained using netting analysis. In further research, this finding can be used as an extra modeling constraint in parameter estimation from clinical data.
authors.affiliation: Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands. A.v.d.Horst@tue.nl
authors.forename: Arjen
authors.initials: A
authors.lastname: van der Horst
authors.forename: Chantal N
authors.initials: CN
authors.lastname: van den Broek
authors.forename: Frans N
authors.initials: FN
authors.lastname: van de Vosse
authors.forename: Marcel C M
authors.initials: MC
authors.lastname: Rutten
mesh_terms: D000465:Algorithms; D000818:Animals; D001158:Arteries / Q000473:pathology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003331:Coronary Vessels / Q000473:pathology*; D004867:Equipment Design; D006333:Heart Failure / Q000503:physiopathology; D006801:Humans; D006874:Hydrostatic Pressure; D008955:Models, Cardiovascular; D015233:Models, Statistical; D008962:Models, Theoretical; D011312:Pressure; D013314:Stress, Mechanical; D013552:Swine