Evaluation of porcine valves prepared by dye-mediated photooxidation

Background. Previous studies demonstrated that dye-mediated photooxidation can stabilize bovine pericardium. Here, photooxidized porcine valve cusp an d root tissue were assessed in comparison to fresh and glutaraldehyde-treat ed samples. Methods and Results. In an in vitro tissue solubility test, both photooxidi zed and glutaraldehyde-treated tissues were resistant to protein extraction compared to fresh tissue. A rat subcutaneous model was used to test in viv o stability and calcification potential. In this study, four of the six fre sh leaflets were not visible because of resorption while both photooxidized and glutaraldehyde-treated tissues were biostable. Mineral contents of the rat explants were much lower for both fresh and photooxidized leaflets whe n compared with glutaraldehyde-treated leaflets. Also, the aortic root calc ified whether treated or not with the most mineral being associated with gl utaraldehyde-treated root. Analysis of photooxidized porcine valves explant ed from the mitral position in sheep indicated a material that was biostabl e and contained only minor calcification, perhaps due to deformed stents. Conclusions. Porcine valve tissue treated by dye-mediated photooxidation is biostable and resistant to calcification, and has potential for use in hea rt valve bioprostheses. (C) 1998 by The Society of Thoracic Surgeons.