A Novel Cross-linked Poly(vinyl alcohol) (PVA) for Vascular Grafts

Poly(vinyl alcohol) (PVA) is a water-soluble synthetic polymer with excellent film-forming, emulsifying, and adhesive properties. The aim of this study is to design a simple process for PVA cross-linking with sodium trimetaphosphate to form membrane devices suitable for biomedical applications. This procedure requires no organic solvent, nor melting process to obtain films with high mechanical strength. Fabrication of a small diameter tube from a PVA film is easy with a single wrapping step around a Teflon rod. Dynamic mechanical analysis demonstrated that, upon removal of the applied stress, the PVA film with a Young's modulus of 2 x 10(5) kPa returns to its original size and shape. The wall thickness of PVA tubes is 344 +/- 13 mu m (n = 12), which is close to the wall thickness of a human artery (350-710 mu m). Suture retention of a PVA tube is excellent (140 +/- 11 g), close to that of human vessels. The burst pressure of PVA tubes is found to be 507 +/- 25 mm Hg, more than three times higher than the human healthy systolic arterial pressure. Under arterial pressure, there was no leakage even after needle puncture, contrary to clinical vascular expanded polytetrafluoroethylene prostheses. Finally, PVA tubes of 2 mm in diameter are used to replace a segment of an infrarenal aorta in rats. For at least one week, no mechanical nor thrombotic complications are noticed even in the absence of anticoagulant or antiplatelet treatment. Graft patency is also evidenced with non-invasive imaging techniques. As a conclusion, this novel cross-linking method confers to poly(vinyl alcohol) particular mechanical properties such as compliance, elasticity and resistance to mechanical stress, compatible with the circulatory blood flow.