Calcification of Experimental Valve Bioprostheses

Abstract

Bovine pericardial strips, porcine valve strips, and canine valve strips were treated with 0.625% glutaraldehyde and implanted subdermally in rats. Weight and calcium content were examined 9 weeks later. Bovine pericardial strips underwent calcification after implantation; electron microscopy showed concentric electron-dense calcified deposits in the collagen fibers. Implanted porcine valve strips also underwent calcification; electron microscopy showed concentric electron-dense calcified deposits in the interstitium. Calcification was also detected in canine valve strips after implantation, but the proportion of calcium was lower than in the other tissues; electron microscopy showed collagen bundles with speckled calcified granules. The process of calcification started on the surface of the collagen fibrils and in the interfibrillar space. It was concluded that preservation of collagen fibers would be helpful in preventing calcification. The use of canine cardiac valves might improve the durability of bioprostheses.