PREVENTION OF CALCIFICATION OF TISSUE VALVES

In this study an attempt was made to find an optimum method of chemica l treatment to prevent the calcification of bioprosthetic heart valves . Bovine pericardium was washed in a 5% sodium chloride solution follo wed by trypsin (Tr) treatment and was kept in 0.1% glutaraldehyde (GA) with a gradual increase in concentration up to 0.25% GA and finally p osttreated with a 4% chitosan (Ch) solution. Fresh, 0.2% GA, 0.625% GA , and sodium chloride-Tr-GA treated pericardial samples were taken for comparative study. Tensile testing showed comparable strength and elo ngation at the breaking point for all groups. The thermal shrinkage st udies indicated merit of the proposed treatment (5% sodium chloride-tr ypsin-glutaraldehyde treated pericardia with chitosan and without chit osan posttreatment). Collagenase assay showed that all differently tre ated (GA) materials were equally resistant to collagenase. All samples were implanted subcutaneously in rats for 2, 4, 8, or 12 weeks for ca lcification study. Morphological and mineral analyses showed complete prevention of calcification in sodium chloridetrypsin-GA-chitosan trea ted pericardium (Ca was 1.1 +/- 0.27 mg/g, von Kossa 0) at the 12th we ek of implantation.