It is a fundamental assumption that a repaired mitral valve (MV) or MV replacement should mimic the functionality of the native MV as closely as possible. Thus, improvements in valvular treatments are dependent on the establishment of a complete understanding of the mechanical properties of the native MV. In this work, the biaxial mechanical properties, including the viscoelastic properties, of the MV anterior leaflet (MVAL) were explored. A novel high-speed biaxial testing device was developed to achieve stretch rates both below and beyond in-vitro values reported for the MVAL (Sacks et al, ABME, Vol. 30,pp. 1280-90, 2002). Experiments were performed with this device to assess the effects of stretch rate (from quasi-static to physiologic) on the stress-stretch response in the native leaflet. Additionally, stress-relaxation and creep tests were performed on the MVAL under physiologic biaxial loading conditions.
The results of these tests showed that the stress-stretch responses of the MVAL during the loading phases were remarkably independent of stretch rate. The results of the creep and relaxation experiments revealed that the leaflet exhibited significant relaxation, but unlike traditional viscoelastic biological materials, exhibited negligible creep.
These results suggested that the MVAL may be functionally modeled as an anisotropic quasi-elastic material and highlighted the importance of performing creep experiments on soft tissues. Additionally, this study underscored the necessity of performing biaxial experiments in order to appropriately determine the mechanical properties of membranous tissues.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04132005-201559 |
| Date | 20 June 2005 |
| Creators | Grashow, Jonathan Sayer |
| Contributors | Michael Sacks, Richard Debski, Jiro Nagatomi |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-04132005-201559/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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