Structural Model for Viscoelastic Properties of Pericardial Bioprosthetic Valves.

The study compares the mechanical properties specifically the viscoelastic behavior of bovine, equine, and porcine pericardium tissues used for bioprosthesis. The results illustrate that porcine pericardium exhibits more elastic and less viscous behavior compared to bovine and equine tissues.

Research Methodology

In this scientific study, the researchers used a few methods to obtain their results:

• The experiment mainly focused on examining the viscoelastic behavior of pericardium tissues of cows (bovine), horses (equine), and pigs (porcine).
• After fixation of these tissues using glutaraldehyde, uniaxial tests were executed to observe how the tissues would react to different extension rates affecting the fiber direction.
• Next, stress relaxation tests were performed on the tissues, applying strains ranging from 20 to 50 percent.
• Upon the evaluation of viscoelastic linearity, different models such as the Prony series, the quasilinear viscoelastic (QLV), and the modified superposition theory were applied to the stress relaxation data. The parameters of these constitutive models were then extracted for each pericardium tissue.

Research Findings

The findings from this study include:

• All three types of pericardium tissue demonstrated a nonlinear viscoelastic trend. This was deduced through the decrease in relaxation rate with elevating strain observed in all tissue samples.
• The three-term Prony model was identified as the best tool for describing the linear viscoelasticity of the tested tissue samples.
• Among the different models, the QLV model was most effective in capturing the relaxation behavior of the pericardium tissues.
• Porcine pericardium was found to be more stiff compared to bovine and equine pericardium. Furthermore, the relaxation percentage of the porcine pericardium was observed to be less than the other two.

Conclusions

Based on the study’s findings, the researchers concluded that porcine pericardium acts more like an elastic tissue and less as a viscous tissue when compared to bovine and equine pericardium. This suggests that porcine pericardium may be a more suitable tissue to use as a basis for aortic valve bioprosthesis.