Impact of glutaraldehyde on calcification of pericardial bioprosthetic heart valve material.

Abstract

This study was conducted to investigate the impact of the preservation method of bioprosthetic heart valve materials on calcification rates and biocompatibility of the biologic tissue. In subcutaneous rat implants, conventionally preserved bioprosthetic heart valve material was compared with bovine pericardium that was treated with L-glutamic acid to reduce residual glutaraldehyde released from the fixed tissue. Both these methods were compared with bovine pericardium that was stabilized by a dye-mediated photooxidation reaction without glutaraldehyde. Biocompatibility of these biomaterials was tested in vitro using human endothelial cell cultures. Conventionally preserved bovine pericardium with a high amount of glutaraldehyde incorporated into the tissue resulted in severe calcification 63 days after subcutaneous implantation in rats (165.4 +/- 20 mg Ca2+/g dry weight). Postfixation treatment with L-glutamic acid, which reduces free, unbound aldehyde groups, showed a significant decrease in calcification (89.6 +/- 14 mg Ca2+/g dry weight). Glutaraldehyde-free preservation by dye-mediated photooxidation showed no calcification after 63 days of subcutaneous implantation (1.0 +/- 0.4 mg Ca2+/g dry weight). Regular endothelial cell proliferation was observed on photooxidized and L-glutamic acid-treated tissue, whereas conventionally treated tissue caused endothelial cell death. This study underlines the detrimental role of glutaraldehyde in the calcification process of bioprosthetic heart valve materials and emphasizes alternative preservation methods that reduce or avoid the use of glutaraldehyde.