[A new approach to the creation of heart valve xenograft bioprostheses resistant to calcification].

The calcium binding activity of xenograft tissue in stages of modification with papain, diphosphonates, and heparin was studied on a model of accelerated calcification in subcutaneous implantation of cusps of pig's aortic bioprostheses to 42 rats. In immobilization of 3-amino-1-oxypropylidendiphosphonic acid and xydiphon the amount of calcium in the implants reduced 50 times as compared to the control. The first stage of ion-covalent heparin immobilization--treatment with albumin--increased the calcium-binding activity of the biomaterial, but subsequent heparinization reduced again the calcium content in the cusp tissue to the level attained in the stage of diphosphonate immobilization. The results of the chemical analysis correlated with the findings of morphological examination. Besides, the new method of treatment made it possible to increase the strength of the biological tissue by 20%. This method of storage of bioprostheses is promising for clinical approbation.