Characterization of arteries and tissue engineered vascular grafts using experimental and finite element models

Abstract

In this dissertation, a methodology for comparing large arteries and tissue engineered vascular grafts is presented. This methodology is based on general porohyperelastic transport swelling theory (PHETS). Suites of experiments are introduced to determine material and transport properties of each vessel. These properties include elasticity, permeability, diffusivity, and convection coefficient. Finite element models (FEMs) were then used to model investigate arterial wall fluid flow and mobile species transport under quasi-static and pulsatile conditions. Rabbit carotid arteries were compared to rabbit aortas. The carotid was more elastic and permeable then the aorta. The pulsatile fluid wall flux was very different from the quasi-static and pulsatile in vivo conditions in these vessels. Tissue engineered vascular grafts (TEVGs) were fabricated in a bioreactor using high and low wall shear stress conditions. The elevated stiffness of ePTFE TEVGs significantly affects the fluid and species transport under both quasi-static and pulsatile conditions. A repeating influx/efflux condition developed in the large arteries and TEVGs during pulsatile pressurization. These conditions provide fluid/species transport pathways in arteries and TEVGs in pulsatile environments. The theoretical basis for ABAQUS FEMs coupled convection/diffusion of neutral species and water was developed. This will allow the analysis of mobile species concentration and flux in complex FEMs of soft biological structures. The theory and FEMs should also be useful in the study of vascular diseases, TEVG development, and drug transport in soft tissues.