CHANGES IN PROPERTIES OF MEDICAL GRADE POLYURETHANE, CARDIOTHANE, AFTER IMPLANTATION

Abstract

Cardiothane films were subcutaneously implanted in the back of rats for up to 2 years. The retrieved films showed discoloration and opacification, but any apparent fragmentation or damage was not observed. SEM analysis revealed that fine cracks appeared after 6 months and then developed gradually. In ATR-FTIR spectra, the relative intensity of bands at 1367 and 1103cm^-1 due to polyether groups decreased. The 1729cm^-1 band of non-hydrogen bonded urethane carbonyl diminished significantly compared to the band at 1698cm^-1 of hydrogen bonded one. The hydrolysis of non-hydrogen bonded urethane linkage occurred during implantation and surface polyether content decreased. However, no appreciable changes in the tensile strength or the elongation at failure took place, since the degradation was limited only to the surface layer.