Passive mechanical properties and constitutive modeling of blood vessels in relation to microstructure.

Mechanical property variations of blood vessels from different anatomical sites supposedly reflect variations in microstructure, but no explicit association has been afforded so far. The objective of the present study was to provide precise histometrical and mechanical data, allowing the identification of such an association for arteries and veins. For biomechanical characterization, a one-dimensional (1D) constitutive model was developed adopting a 'Fung-type' exponential function to reproduce the stiffening effect of blood vessels at high stresses and combining it with a power function to reproduce the low-stress response. Histometrical studies were conducted with quantification of fiber composition and waviness for the entire vessel and its layers. Significant correlations were found between the model parameters and extracellular matrix organization. The novel model associates with recently-derived strain-energy functions for the arterial wall, provides powerful fit to uniaxial tension data from all types of vascular tissue studied, and conforms explicitly to microstructure.