Comparison of biaxial mechanical and microstructural properties between human femoral arteries and surrogate models for stent development.

Abstract

Stents are essential medical devices for treating peripheral artery disease, but the outcomes of design testing depend strongly on the mechanical environment in which they are deployed. During stent development, surrogate arterial models are commonly used to reproduce the pulsatile behaviour and geometry of human arteries, according to standards requirements. However, these surrogates differ from the mechanical properties of living human arteries. This study compared eight materials commonly used in vascular devices development with fresh human arteries as reference. The tested materials were frozen human femoral artery, preserved human femoral artery, fresh and frozen sheep carotid artery, fresh and frozen pig abdominal aorta, basic silicon and technical silicon. Samples were tested on a planar bi-axial testing machine to quantify their mechanical properties. Stress and strain data were analyzed in the longitudinal and circumferential directions under nine different strain rate ratios. Bi-linear and constitutive model fitting were applied to describe and compare mechanical responses. Histological analysis characterized the structure and composition of each biological material, and constitutive parameters inferred from histology were numerically fitted. Frozen human femoral arteries and fresh pig abdominal aortas were identified as the closest models to human femoral arteries when comparing toe, high stress stiffness, diameter and thickness (utility score values of 9.44 and 8.38 respectively). No material fully matched the stiffness for both slopes and transition strain thresholds. Further research is needed to design surrogate materials that more accurately reproduce the mechanical behaviour of living arteries and support reproducible and physiologically relevant vascular testing.