WALL STRUCTURES INFLUENCE ON PATENCY IN MICROPOROUS POLYURETHANE SMALL DIAMETER VASCULAR GRAFTS

Abstract

(Introduction)We previously reported that hydraulic permeability leads to satisfactory patency of a microporous small diameter vascular graft with a fibrous polyurethane (PU) graft wall. In this reports, the PU grafts were evaluated in terms of PU fiber diameter, porosity, and hydraulic permeability (HP). (Methods)Microporous PU vascular grafts (internal diameter: 1.5mm) were fabricated by a spray-phase inversion technique. Porosity (vacancy ratio inside a graft wall) and PU fiber diameters were measured using scanning electron micrographs. Those grafts (length: 10–16 mm) were implanted in the rat abdominal aorta (n=6), and were retrieved 1 month after implantation. No antithrombo-genic agent was administered either before or after implantation. (Results)The internal surface areas(%) with PU fiber diameters less than 3 pm in the 3 patent grafts were 47, 52, and 61 %, respectively, while those in the 3 occluded grafts were all 0 %. The mean wall porosity of the patent grafts and the occluded grafts were 44.7±7.9% and 1 7.9t2.1%, respectively. The mean HP of the patent grafts and the occluded grafts were 38.3±19.2 ml/min/cm2 and 2.420 ml/min/cm2, respectively. (Conclusions)It seems that grafts with more amount of thinner PU fibers, more porosity and more HP develop less thrombosis and, thus have better patency. Currently, further studies of relationships between 3 dimensional structure of graft wall and patency are in progress.