LABORATORY EVALUATION OF TISSUE HEART-VALVES - A COMPARATIVE-ASSESSMENT

Tissue of commercially prepared tissue heart valves were evaluated and compared with aluminium treated, fixed porcine valve tissue in vitro (tensile strength, scanning and transmission electron microscopy) and in vivo (calcification potential after subcutaneous implantation in th e rat model), Valve leaflets (n=40) were devided into four groups acco rding to the method of treatment: Group I (fixed in 0.652% glutaraldeh yde, control), Group II (fixed and treated with aluminium), Group III (fixed and treated with Toluidine blue) and Group IV (fixed and treate d with watersoluble alkyl sulphate), Tensile strength was not influenc ed in Group II and III (p>0.05). Group IV indicated a significant (p<0 .05) reduction in tensile strength. Scanning electron microscopy revea led damage and loss of surface endothelium in Group III and IV respect ively. Transmission electron microscopy indicated damage to underlying matricial cells in Group III and IV. Calcification potential was sign ificantly (p<0.001) reduced in Group II to IV. We conclude that damage d ultrastructure could contribute to the reduced tensile strength in G roup IV and that reduced tensile strength might have an influence on t he long-term durability of tissue heart valves. Antimineralization tre atment of tissue heart valves does retard calcification but is yet una ble to inhibit the process completely.