, Volume 5, Issue 4, pp 157-169

A Mechanical Model of Porcine Vascular Tissues-Part II: Stress–Strain and Mechanical Properties of Juvenile Porcine Blood Vessels

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Abstract

Our laboratory is studying the influence of the volume fractions and the organization of various macromolecules and cells in vascular tissue on the physical properties of vessel wall. The current investigation reports various mechanical properties of aorta, vena cava, carotid artery and iliac artery of the swine including: low-strain and high-strain moduli, transition from low-strain to high-strain behavior, the ultimate tensile stress, and the ultimate strain. Tissues were tested using a uniaxial incremental stress–strain technique, which allowed us to capture viscous, elastic, and total data simultaneously. Vessels were strained throughout their entire strain range until failure was achieved. Low-strain modulus showed sporadic differences between blood vessels and some dependence on strain-rate. The high-strain modulus was consistently greater in vena cava (2.2 MPa for viscous stress–strain—9.6 MPa for total stress–strain) than other vessels. The ultimate tensile strength of vena cava (0.46 MPa for viscous and 2.5 MPa for total) was again greater than in other vessels and there was some strain-rate dependence. The ultimate strain of carotid artery (180%) was greater in the transverse direction than in other vessels. Viscosity measurements indicated that blood vessels are thixotropic (viscosity decreased 2 orders of magnitude for 2 orders of magnitude increase in strain-rate). Our data suggests that differences in mechanical properties of blood vessels occur depending on where in the vascular tree the tissue is located. These differences may be required by the physiological and mechanical demands on individual vessels.