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Journal of Long-Term Effects of Medical Implants

ISSN Print: 1050-6934
ISSN Online: 1940-4379

Journal of Long-Term Effects of Medical Implants

DOI: 10.1615/JLongTermEffMedImplants.2015011741
pages 41-53

On the Bending Properties of Porcine Mitral, Tricuspid, Aortic, and Pulmonary Valve Leaflets

Bryn Brazile
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi
Bo Wang
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi; Department of Biomedical Engineering, Alabama State University, Montgomery, Alabama
Guangjun Wang
Tissue Bioengineering Laboratory, Department of Biological Engineering, Mississippi State University, MS, 39762
Robbin Bertucci
Tissue Bioengineering Laboratory, Department of Biological Engineering, Mississippi State University, MS, 39762
Raj Prabhu
Tissue Bioengineering Laboratory, Department of Biological Engineering, Mississippi State University, MS, 39762
Sourav S. Patnaik
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi
J. Ryan Butler
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi
Andrew Claude
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi
Erin Brinkman-Ferguson
Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, MS, 39762
Lakiesha N. Williams
Tissue Bioengineering Laboratory, Department of Biological Engineering, Mississippi State University, MS, 39762
Jun Liao
Department of Biological Engineering and College of Veterinary Medicine, Mississippi State University, Mississippi

ABSTRACT

The atrioventricular valve leaflets (mitral and tricuspid) are different from the semilunar valve leaflets (aortic and pulmonary) in layered structure, ultrastructural constitution and organization, and leaflet thickness. These differences warrant a comparative look at the bending properties of the four types of leaflets. We found that the moment−curvature relationships in atrioventricular valves were stiffer than in semilunar valves, and the moment−curvature relationships of the left-side valve leaflets were stiffer than their morphological analog of the right side. These trends were supported by the moment−curvature curves and the flexural rigidity analysis (EI value decreased from mitral, tricuspid, aortic, to pulmonary leaflets). However, after taking away the geometric effect (moment of inertia I), the instantaneous effective bending modulus E showed a reversed trend. The overall trend of flexural rigidity (EI: mitral > tricuspid > aortic > pulmonary) might be correlated with the thickness variations among the four types of leaflets (thickness: mitral > tricuspid > aortic > pulmonary). The overall trend of the instantaneous effective bending modulus (E: mitral < tricuspid < aortic < pulmonary) might be correlated to the layered fibrous ultrastructures of the four types of leaflets, of which the fibers in mitral and tricuspid leaflets were less aligned, and the fibers in aortic and pulmonary leaflets were highly aligned. We also found that, for all types of leaflets, moment−curvature relationships are stiffer in against-curvature (AC) bending than in with-curvature bending (WC), which implies that leaflets tend to flex toward their natural curvature and comply with blood flow. Lastly, we observed that the leaflets were stiffer in circumferential bending compared with radial bending, likely reflecting the physiological motion of the leaflets, i.e., more bending moment and movement were experienced in radial direction than circumferential direction.