Elastic behaviour of sutured calf pericardium: influence of the suture threads

The purpose of this study was to assess the elastic behaviour of calf pericardium used in the construction of cardiac bioprosthesis valve leaflets, sutured with different types of commercially available sutures: silk, Gore-Tex, Surgilene and nylon. Thirty-two samples (four series of eight samples each) were subjected to tensile strength testing to breakage. The breaking stress (MPa) ranged between 4.89 MPa for samples sutured with Gore-Tex and 5.22 MPa for those sewn with nylon. Three samples from each series were subjected to a stepwise stress test, involving increasing levels of stress followed by return to zero, to define the elastic limit (the cut-off point beyond which strain is no longer reversible). Analysis of the results provided the mathematical functions that govern the elastic behaviour (stress/strain) within the elastic range for each type of sutured sample. The series sutured with Surgilene presented the highest mean value (1.649 MPa). Finally, a statistical study was carried out to determine which series showed the greatest probability of having the least interaction between the thread and the pericardium. Allowing an interval of +/- 10%, Gore-Tex showed the best probability in this respect. However, real fatigue testing is necessary to definitively determine which is the best suture to use.