Biaxial mechanical properties of the native and glutaraldehyde-treated aortic valve cusp: Part II--A structural constitutive model.
We have formulated the first constitutive model to describe the complete measured planar biaxial stress-strain relationship of the native and glutaraldehyde-treated aortic valve cusp using a structurally guided approach. When applied to native, zero-pressure fixed, and low-pressure fixed cusps, only three parameters were needed to simulate fully the highly anisotropic, and nonlinear in-plane biaxial mechanical behavior. Differences in the behavior of the native and zero- and low-pressure fixed cusps were found to be primarily due to changes in the effective fiber stress-strain behavior. Further, the model was able to account for the effects of small (< 10 deg) misalignments in the cuspal specimens with respect to the biaxial test axes that increased the accuracy of the model material parameters. Although based upon a simplified cuspal structure, the model underscored the role of the angular orientation of the fibers that completely accounted for extreme mechanical anisotropy and pronounced axial coupling. Knowledge of the mechanics of the aortic cusp derived from this model may aid in the understanding of fatigue damage in bioprosthetic heart valves and, potentially, lay the groundwork for the design of tissue-engineered scaffolds for replacement heart valves.
Billiar
K L
KL
Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33124, USA.
Sacks
M S
MS
D000818:Animals; D016880:Anisotropy; D001021:Aortic Valve / Q000502:physiology* / Q000637:transplantation*; D001696:Biomechanical Phenomena; D001705:Bioprosthesis / Q000009:adverse effects; D001794:Blood Pressure / Q000502:physiology; D005404:Fixatives / Q000009:adverse effects*; D005976:Glutaral / Q000009:adverse effects*; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D018056:Hemorheology; D006801:Humans; D008422:Materials Testing; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D009716:Numerical Analysis, Computer-Assisted; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012680:Sensitivity and Specificity; D013552:Swine; D013718:Tensile Strength
D005404:Fixatives; D005976:Glutaral