Hydrophobic and fibrillar microporous polyetherurethane urea prosthesis: an ESCA study on the internal and external surfaces of explanted grafts.

The ESCA study gives a good qualitative and quantitative elemental analysis of internal and external surfaces of foreign materials. Microporous hydrophobic Mitrathane (a polyetherurethane urea) grafts were implanted as blood conduits in dogs for up to 6 months. Surface analysis of explanted grafts demonstrated the presence of different contaminants: sodium, chlorine, silicon, in patent grafts, i.e. those implanted for 1 month and less. The sulphur probably comes from the presence of proteins on the surface of the polymer and the high level of nitrogen is also protein-related. At 6 month implantation, the grafts were occluded and a decrease of proteins on the surface was observed. The values of N/C and O/C ratios are also reported. For the virgin material, these ratios correspond to the quantity of hard and soft segments; but, for the explanted grafts, these parameters are also influenced by the presence of proteins due to the Versaclean washing which did not wash away all the proteins on the surface of the polymer. The SEM photographs showed a certain degradation of polyurethane after 6 month of implantation. However, by ESCA study, it is difficult to compare the surface of virgin and explanted grafts because it is masked by the presence of proteins.