The relationship between stress and relaxation in calf pericardium used in the construction of cardiac bioprostheses

Abstract Assessment of relaxation (loss of load within a given time) without apparent deformation is a necessary step before durability assay of biomaterials. From results obtained using calf pericardium, the following conclusions were drawn: (a) there is no limit to relaxation for this biomaterials, (b) the lesser the load applied, the greater the relaxation, and (c) the relaxation curve follows the logarithmic function γ = k 1 - K 2 - Inf. These findings demonstrate the poor behaviour of the biomaterial at supposedly low loads and suggest that rupture-point load is not a reliable reference to determine the safety coefficient of calf pericardium used in cardiac bioprostheses.