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Annals of Biomedical Engineering

, Volume 34, Issue 2, pp 315–325 | Cite as

Biaixal Stress–Stretch Behavior of the Mitral Valve Anterior Leaflet at Physiologic Strain Rates

  • Jonathan S. Grashow
  • Ajit P. Yoganathan
  • Michael S. SacksEmail author
Article

Abstract

Characterization of the mechanical properties of the native mitral valve leaflets at physiological strain rates is a critical step in improving our understanding of MV function and providing experimental data for dynamic constitutive models. We explored, for the first time, the effects of strain rate (from quasi-static to physiologic) on the biaxial mechanical properties of the native mitral valve anterior leaflet (MVAL). A novel high-speed biaxial testing device was developed, capable of achieving in vitro strain rates reported for the MVAL (Sacks et al., Ann. Biomed. Eng. 30(10):1280–1290, 2002). Porcine MVAL specimens were loaded to physiological load levels with cycle periods of 15, 1, 0.5, 0.1, and 0.05 s. The resulting loading stress–strain responses were found to be remarkably independent of strain rate. The hysteresis, defined as the fraction of the membrane strain energy between the loading and unloading curves tension-areal stretch curves, was low (∼12%) and did not vary with strain rate. The results of the present work indicated that MVAL tissues exhibit complete strain rate insensitivity at and below physiological strain rates under physiological loading conditions. These novel results suggest that experimental tests utilizing quasi-static strain rates are appropriate for constitutive model development for mitral valve tissues. The mechanisms underlying this quasi-elastic behavior are as yet unknown, but are likely an important functional aspect of native mitral valve tissues and clearly warrant further study.

Keywords

Mitral valve Heart valves Biaxial mechanical properties Strain rate Stress–strain relation 

Notes

ACKNOWLEDGMENTS

This work was funded by NIH grant HL-52009. MSS is an Established Investigator of the American Heart Association.

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Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  • Jonathan S. Grashow
    • 1
  • Ajit P. Yoganathan
    • 2
  • Michael S. Sacks
    • 1
    • 3
    Email author
  1. 1.Engineered Tissue Mechanics Laboratory, Department of Bioengineering, McGowan Institute for Regenerative MedicineUniversity of PittsburghPittsburghUSA
  2. 2.Department of Biomedical EngineeringGeorgia Institute of TechnologyAtlantaUSA
  3. 3.Department of BioengineeringUniversity of PittsburghPittsburghUSA

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