A two-dimensional incremental study of the static mechanical properties of vascular grafts

Abstract

We have used a two-dimensional incremental model to examine the static mechanical properties of canine iliac artery and, with a view to compliancematching, the properties of several vascular grafts: expanded PTFE grafts, human umbilical cord vein grafts (HUV) and helically-wound prototype polyurethane grafts with wrap angles of 30°, 45°, and 60°. Whole vessels were tested in the isotonic mode under physiological conditions using a video analysis system. Using the incremental analysis, circumferential and longitudinal moduli and the two Poisson ratios were derived at operating points of 80, 100, 120, 140, and 160 mm Hg pressure and 30 g end-load (or in vivo end-load for the arterial samples). The model can be manipulated to produced excellent predictions of results from the more common compliance testing. While the PTFE and HUV samples were much stiffer than the natural vessels, a polyurethane graft with a wrap angle of approximately 45° is a good match for canine iliac artery.