| 摘要: | Biological materials have been used as prosthetic devices such as heart valves, vascular grafts, and pericardial patches, These biological materials have to be fixed with crosslinking reagents and sterilized subsequently before they can be implanted in humans, Recently, a new crosslinking reagent, epoxy compound, has been used to fix bioprostheses. In this fixation technique, heparin may be ionically bound on the tissue surface, It has been shown that the amount of heparin bound to the tissue surface is proportional to the quantity of protamine impregnated in the biological tissues, However, it is not known if the impregnation of protamine will affect the crosslinking density of the biological tissues, This study was designed to compare the crosslinking densities of the epoxy compound fixed biological tissues with or without heparinization, Fresh porcine aortic valves procured from a slaughter house were first impregnated in various concentrations of protamine sulfate (0, 0.5, 1.0, or 1.5%) for about 30 min, The porcine aortic valves were then crosslinked in a 4% epoxy compound solution (Denacol(R) EX-313), The porcine samples were taken out at various elapsed fixation periods: 18, 25, 48, 72, 96, and 120 h. Finally, the crosslinked porcine aortic valves were heparinized in a 0.5% sodium heparin solution for about 1 h. The crosslinking densities of the porcine leaflet and the aortic wall of each sample were determined by measuring their shrinkage temperatures, It was revealed that the impregnation of various concentrations of protamine did not seem to significantly alter the shrinkage temperatures of the porcine leaflet and the aortic wall throughout the entire fixation process (p > 0.05), This indicated that the impregnation of protamine did not significantly change the crosslinking density of the biological tissues, However, it was found that protamine tended to discolor the tissue and to stiffen the porcine leaflet and the aortic wall, Although the impregnation of protamine did not seem to significantly alter the crosslinking density of the epoxy compound fixed biological tissues, the increase of the stiffness of the heparinized tissues may cause concerns in some clinical applications. (C) 1995 John Wiley and Sons, Inc. |
