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. 2020:1:197-202.
doi: 10.1109/ojemb.2020.3002450. Epub 2020 Jun 15.

Rate-Dependent and Relaxation Properties of Porcine Aortic Heart Valve Biomaterials

Christopher Noble  1 , Michael Kamykowski  1 , Amir Lerman  1 , Melissa Young  1
Affiliations

Rate-Dependent and Relaxation Properties of Porcine Aortic Heart Valve Biomaterials

Christopher Noble et al. IEEE Open J Eng Med Biol. 2020.

Abstract

Objective: This work evaluates the rate-dependent and relaxation properties of native porcine heart valves, glutaraldehyde fixed porcine pericardium, and decellularized sterilized porcine pericardium.

Methods: Biaxial tension testing was performed at strain-rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 1 s-1. Finally, relaxation testing for 300 s was performed on all heart valve biomaterials.

Results: No notable rate-dependent response was observed for any of the three biomaterials with few significant differences between any strain-rates. For relaxation testing, native tissues showed the most pronounced drop in stress and glutaraldehyde the lowest drop in stress although no tissues showed anisotropy in the relaxation.

Conclusions: Increasing the strain-rate of the three biomaterials considered does not increase the stress within the tissue. This indicates that there will not be increased fatigue from accelerated wear testing compared to loading at physiological strain-rates as the increase strain-rates would likely not significantly alter the tissue stress.

Keywords: Aortic valve replacement; Biaxial tension; rate-dependency; relaxation testing; tissue engineered heart valve.

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Figures

FIGURE 1.
FIGURE 1.
First Piola-Kirchhoff (PK1) stress versus stretch curves for mean native aortic valve cusp data for the first loading protocol (10% applied equibiaxial strain; N-1) and the second loading protocol (30% applied strain in x1 and 10% applied strain in x2; N-2). Mean glutaraldehyde fixed (G-1 and G-2) and decellularized-sterilized pericardium (DS-1 and DS-2) curves are also shown. Purple diamonds illustrate points where stress was found at λc and λc/2.
FIGURE 2.
FIGURE 2.
First Piola-Kirchhoff (PK1) stress versus stretch curves for silicone rubber tested without the preconditioning protocol.
FIGURE 3.
FIGURE 3.
First Piola-Kirchhoff (PK1) stress versus stretch curves for silicone rubber tested with the preconditioning protocol.
FIGURE 4.
FIGURE 4.
Mean relaxation curves for native valvular cusps, glutaraldehyde fixed pericardium, and decellularized-sterilized pericardium with first Piola-Kirchhoff (PK1) Stress (A) or stress normalized (B).
FIGURE 5.
FIGURE 5.
Tissue test apparatus showing the four independent arms, the biorakes, and the camera to record marker positions.
See this image and copyright information in PMC

References

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