The in vitro mechanical properties of small diameter Poly(vinyl) alcohol hydrogel (PVA) plus dextran (Dx) based vascular grafts.

Abstract

Introduction The production of artificial vascular grafts of small diameter is a fluorescing line of investigation. PVA is a biomaterial that has been used for several biomedical applications and nowadays as a vascular graft. However the mechanical properties were never characterized in vitro. It was our objective to produce small diameter PVA grafts and characterize their physical and mechanical properties for posterior evaluation in a large animal model. Methods PVA vascular grafts were prepared by the physical reticulation technique freeze/thawing plus annealing and were made with 5 cm of length and an internal diameter of 5 mm. PVA was associated to dextran in 1% concentration. For the physical properties were addressed tests to determine wettability and electrical charge; and the mechanical properties were characterized according to the ISO standard 7198:1998 using burst pressure and dynamic mechanical analysis. Results and discussion Graft wettability was determined by contact angle (56.5º±0.2) and the surface was considered hydrophilic facilitating endothelial cell adhesion. Burst pressure evidenced the resistance of the graft to a maximum value of inner pressure (3.8±0.3 bar) compatible to the documented values for human large arteries. The elasticity of grafts is important due to the pulsatile nature of the flow in arterial conduits. The young modulus is a reflexion of that elasticity and the value for this artificial graft was 9.8x104±4.8x103 Pa which is close to the documented value for arteries. Conclusions The results of physical and mechanical characterization make this vascular graft a successful candidate for further in vivo characterization in a large animal model.