Site specific inelasticity of arterial tissue

Abstract

1Understanding the mechanical behaviour of arterial tissue is vital to the development and 2 analysis of medical devices targeting diseased vessels. During angioplasty and stenting, stress 3 softening and permanent deformation of the vessel wall occur during implantation of the 4 device, however little data exists on the inelastic behaviour of cardiovascular tissue and how 5 this varies through the arterial tree. The aim of this study was to characterise the magnitude 6 of stress softening and inelastic deformations due to loading throughout the arterial tree and 7 to investigate the anisotropic inelastic behaviour of the tissue. Cyclic compression tests were 8 used to investigate the differences in inelastic behaviour for carotid, aorta, femoral and 9 coronary arteries harvested from 3-4 month old female pigs, while the anisotropic behaviour 10 of aortic and carotid tissue was determined using cyclic tensile tests in the longitudinal and 11 circumferential directions. The differences in inelastic behaviour were correlated to the ratio 12 of collagen to elastin content of the arteries. It was found that larger inelastic deformations 13 occurred in muscular arteries (coronary), which had a higher collagen to elastin ratio than 14 elastic arteries (aorta), where the smallest inelastic deformations were observed. Lower 15 magnitude inelastic deformations were observed in the circumferential tensile direction than 16 in the longitudinal tensile direction or due to radial compression. This may be as a result of 17 non-fibrous matrix or smooth muscle in the artery becoming more easily damaged than the 18 collagen fibers during loading. Stress softening was also found to be dependent on artery

Failure and Fatigue Properties of Immature Human and Porcine Parasagittal Bridging Veins

“…Furthermore, there have been few other studies to measure axial behavior of any blood vessel under cyclic loading 19, 20, 25, 32, 43 , with most focused on the first five cycles 19, 20, 25, 32 . Our study was designed to mimic scenarios of repeated single loads or cyclic head rotations in both sports (e.g.…”

Fatigue Damage of Collagenous Tissues: Experiment, Modeling and Simulation Studies

“…106 presented a tissue damage constitutive model with distinct softening and permanent set definitions in the matrix and fibers, while many other tissue damage models only considered permanent set in the fibrous components. 5,103 Maher and Early 107 found that the artery undergoes more significant permanent deformations in the radial direction, thus supporting the inclusion of a non-collagenous matrix permanent set defnition. Briefly, damage effects by the pseudo-elasticity theory 101 are enforced through an additive split of the isochoric stress tensor into the stress softened portion and the inelastic portion.…”

Comparison of transcatheter aortic valve and surgical bioprosthetic valve durability: A fatigue simulation study

“…The GLBP leaflet fatigue response was defined by the hypothetical GLBP fatigue parameters presented in our previous work (Martin and Sun 2013). The permanent set was assumed to be dependent on the matrix damage rather than the fiber damage on account of experimental observations that permanent sets are more significant perpendicular to the preferred fiber orientation in aortic and carotid tissues (Maher, Early et al 2012). The two fiber families were assigned identical material properties and oriented symmetrically about the leaflet material axis in the radial direction illustrated on the 2D leaflet schematic in Figure 1b.…”