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Micromechanics and mathematical modeling: an inside look at bioprosthetic valve function
I Vesely1, S Krucinski, G Campbell
1John P. Robarts Research Institute, London, Ontario, Canada.
Journal of Cardiac Surgery
|March 1, 1992
Summary
Glutaraldehyde fixation causes bioprosthetic valve failure through compressive buckling and inhibited tissue shearing. New micromechanical and modeling techniques reveal stress concentrations, guiding improved valve design for reduced failure.
Area of Science:
- Biomedical Engineering
- Materials Science
- Cardiovascular Research
Background:
- Bioprosthetic heart valves, particularly glutaraldehyde-treated porcine xenografts, are prone to degeneration.
- Valve cusp tearing near commissural attachment to the stent is a primary failure mode.
Purpose of the Study:
- To investigate the micromechanical changes in glutaraldehyde-fixed aortic valves.
- To develop and apply mathematical modeling for simulating valve function and failure modes.
- To identify mechanisms of bioprosthetic valve degeneration.
Main Methods:
- Micromechanical testing of aortic valve tissues.
- Mathematical modeling of valve mechanics throughout the cardiac cycle.
- Evaluation of biomechanical changes induced by glutaraldehyde fixation.
Main Results:
- Compressive buckling identified as a common failure mode in fixed tissues at physiological curvatures.
- Glutaraldehyde fixation inhibits natural cusp shearing and fibrosa-ventricularis interaction.
- Mathematical modeling confirmed stress concentration near valve commissures, reducible by stent modification.
Conclusions:
- Compressive buckling is a likely primary failure mechanism for bioprosthetic valves.
- Current fixation methods negatively impact valve biomechanics.
- Advanced micromechanical and modeling techniques can improve bioprosthetic valve design and evaluation.