title: Constitutive modeling of human saphenous veins at overloading pressures.
abstract: In the present study, inflation tests with free axial extension of 15 human vena saphena magna were conducted ex vivo to obtain data suitable for multi-axial constitutive modeling at overloading conditions (pressures up to approximately 15kPa). Subsequently the data were fitted with a hyperelastic, nonlinear and anisotropic constitutive model based on the theory of the closed thick-walled tube. It was observed that initial highly deformable behavior (up to approximately 2.5kPa) in the pressure-circumferential stretch response is followed by progressive large strain stiffening. Contrary to that, samples were much stiffer in longitudinal direction, where the observed stretches were in the range 0.98-1.03 during the entire pressurization in most cases. The effect of possible residual stress was evaluated in a simulation of the intramural stress distribution with the opening angle prescribed to 0°, 10°, 20°, 30°, 40°, and 50°. The result suggests that the optimal opening angle making the stress distribution through the wall thickness uniform is about 40°. The material parameters presented here are suitable for use in mechanobiological simulations describing the adaptation of the autologous vein wall after bypass surgery.
authors.affiliation: Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 166 07 Prague, Czech Republic. Electronic address: jan.vesely1@fs.cvut.cz.
authors.forename: J
authors.initials: J
authors.lastname: Veselý
authors.affiliation: Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 166 07 Prague, Czech Republic.
authors.forename: L
authors.initials: L
authors.lastname: Horný
authors.affiliation: Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 166 07 Prague, Czech Republic.
authors.forename: H
authors.initials: H
authors.lastname: Chlup
authors.affiliation: Third Faculty of Medicine, Charles University in Prague, Ruska 87, 100 00 Prague, Czech Republic.
authors.forename: T
authors.initials: T
authors.lastname: Adámek
authors.affiliation: General University Hospital in Prague, U Nemocnice 2, 128 08 Prague, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Krajíček
authors.affiliation: Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 166 07 Prague, Czech Republic.
authors.forename: R
authors.initials: R
authors.lastname: Žitný
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D008954:Models, Biological; D011312:Pressure; D012501:Saphenous Vein / Q000033:anatomy & histology / Q000502:physiology*; D013314:Stress, Mechanical; D016474:Weight-Bearing
keywords: Anisotropy; Bypass graft; Collagen; Constitutive model; Saphenous vein; Strain energy density