A new storage solution for porcine aortic valves

The aim of this study was to assess the calcification tendency of two biovalves manufactured by different fixation techniques and compare their biocompatibility when implanted subcutaneously in rats. Two biological valve types (Intact) and Mosaic, stored in either glutaraldehyde or in a solution recently developed in our department, were investigated ultrastructurally and their calcium content was measured following 12 weeks subcutaneous implantation in rats. All valves tested in this study showed a considerable loss of the endothelial cover, as judged by scanning electron microscopy. Independent of fixation conditions, the bioprostheses demonstrated a partial destruction of collagen fibers and a rearrangement of the extracellular matrix. The calcium content of Intact valves was significantly higher than that of Mosaic valves (66+/-2.6 versus 3.6+/-0.6 mg/g dry tissue, p<0.0001). Low calcium content of the bioprostheses is considered to result from effective anti-calcification treatment. Ultrastructural changes of prosthetic tissue seem to promote degenerative calcification. The valves stored in the new storage solution exhibited a calcium content which was reduced by approximately 50% compared to those stored in glutaraldehyde. The percentage of reduction in calcification of the valves stored in our newly developed solution is independent of the fixation conditions (p=0.886). The advantage of the new storage solution is based on the fact that rinsing is unnecessary before implantation and, most importantly, a clear reduction in the calcification tendency is achieved.