Selection and interaction of biomaterials used in the construction of cardiac bioprostheses.

The mechanical behavior of calf pericardium employed in the manufacture of cardiac bioprostheses was assessed according to the region from which it was selected. For this purpose, selected samples of the tissue were sewn with different types of commercially available sutures and subjected to tensile testing, the results of which were compared with the findings in selected, but not sutured, tissue used as a control. The results confirm a loss of resistance--that is, a reduction of the capacity of sutured samples of the biomaterial to withstand breakage stress compared with control samples. Taking into account the marked resistance to breakage of the suture thread, this phenomenon can only be explained as a consequence of the deleterious mechanical interaction between the suture and chemically treated pericardium. This interaction is illustrated by the shearing force which is responsible for the loss of resistance in the tested samples. These trials demonstrate that the results can be improved and the deleterious interaction diminished, although not eliminated, when the pericardium is selected from a given region.