Cells and Materials


Scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDS) have been used to quantify calcium deposition in bioprosthetic valves. To further characterize the calcification process as it pertains to allograft valve tissue, two models of tissue valve implantation were used. The first model used subcutaneous implantation of glutaraldehyde-preserved allogeneic aortic and pulmonary valve leaflets. The second model used syngeneic or allogeneic fresh aortic valve grafts implanted heterotopically into the abdominal aorta of recipient rats. Reference light microscopy was used to select sections for SEM and EDS. In the subcutaneous model, calcium content in both the pulmonary and aortic valves increased up to three weeks, followed by a plateau. The pulmonary leaflets showed greater calcium content than aortic leaflets. In the heterotopic implantation study, calcification occurred to a significantly greater degree in the allogeneic than in the syngeneic valves. This technique may be useful in analyzing the factors that contribute to deterioration of bioprosthetic and allograft valves.