Short-term fatigue testing can predict medium-term pericardium behaviour

The medium-term fatigue behaviour of calf pericardium (similar to the one used to manufacture cardiac bioprostheses valve leaflets) has been studied. 96 samples were tested under fatigue subjecting them to biaxial stress at 1 Hz frequency for 5000 cycles, in 4 series of 24 samples, at several supra-physiological mean pressures and pressure amplitudes. Short-term damage parameters such as the accumulated energy consumption in 10 cycles (E10) and medium-term ones after 5000 cycles like total energy consumption (Et) and maximum displacement of the membrane (Dt) have been evaluated. E10 showed exponential growing tendency with pressure and linear tendency with pressure amplitude when only one parameter curve was plotted. Similar results were found when analysing Et and Dt. Linear correlation models were established between E10 and Et and E10 and Dt. Similar results were achieved in the four series, with excellent determination coefficients. The results confirm that the fatigue behaviour from the very first cycles of the test can predict the medium-term behaviour of the tissue by means of measurement of suitable damage markers. The tendencies observed between the parameters seem to show that the results could have been the same ones if the test had been performed at physiological pressures and amplitudes. This work opens the door to a non-destructive test of the tissue prior to employ it to manufacture valve leaflets.