INFLUENCE OF STRESS ON CALCIFICATION OF DELIPIDATED BOVINE PERICARDIAL TISSUE EMPLOYED IN CONSTRUCTION OF CARDIAC VALVES

Since the development of cardiac bioprostheses, numerous chemical trea tments have been assayed to prevent mineralization. The effectiveness of chemical treatments that eliminate lipids from the tissue was teste d by combining two models. First, handmade bovine pericardial bioprost heses, subjected to chemical treatment with chloroform/methanol and gl utaraldehyde or treated with glutaraldehyde alone for use as controls, were subjected to mechanical stress in a heart valve, accelerated wea r tester (100 x 10(6) consecutive cycles). Then, the bioprostheses wer e un-stitched and tissue samples were taken from the portion subjected to maximal stress (P1) and from that surrounding the sewing ring, whi ch had not been subjected to mechanical stress (P2), for subcutaneous implantation. After 21 and 60 days of implantation, we observed calcif ication of the samples subjected to mechanical stress, even after deli pidating treatment, with no significant differences with respect to th e control group. However, the treated samples from the portion not sub jected to mechanical stress presented a slighter accumulation of calci um after 60-day implantation (5.60 +/- 3.09 mg Ca2+/g dry weight of ti ssue) versus the control group (47.17 +/- 20.4 mg Ca2+/g dry weight of tissue), the difference of which was statistically significant (p < 0 .01). At the time of these medium-term studies, marked calcification w as observed in tissue subjected to delipidating treatment in the zones that underwent mechanical stress. (C) 1996 John Wiley & Sons, Inc.