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Mitral leaflet modeling: Importance of in vivo shape and material properties.
MedLine Citation:
PMID:  21704316     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The anterior mitral leaflet (AML) is a thin membrane that withstands high left ventricular (LV) pressure pulses 100,000 times per day. The presence of contractile cells determines AML in vivo stiffness and complex geometry. Until recently, mitral valve finite element (FE) models have neglected both of these aspects. In this study we assess their effect on AML strains and stresses, hypothesizing that these will differ significantly from those reported in literature. Radiopaque markers were sewn on the LV, the mitral annulus, and AML in sheep hearts, and their four-dimensional coordinates obtained with biplane video fluoroscopy. Employing in vivo data from three representative hearts, AML FE models were created from the marker coordinates at the end of isovolumic relaxation assumed as the unloaded reference state. AML function was simulated backward through systole, applying the measured trans-mitral pressure on AML LV surface and marker displacements on AML boundaries. Simulated AML displacements and curvatures were consistent with in vivo measurements, confirming model accuracy. AML circumferential strains were mostly tensile (1-3%), despite being compressive (-1%) near the commissures. Radial strains were compressive in the belly (-1 to -0.2%), and tensile (2-8%) near the free edge. These results differ significantly from those of previous FE models. They reflect the synergy of high tissue stiffness, which limits tensile circumferential strains, and initial compound curvature, which forces LV pressure to compress AML radially. The obtained AML shape may play a role not only in preventing mitral regurgitation, but also in optimizing LV outflow fluid dynamics.
Authors:
Marco Stevanella; Gaurav Krishnamurthy; Emiliano Votta; Julia C Swanson; Alberto Redaelli; Neil B Ingels
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-23
Journal Detail:
Title:  Journal of biomechanics     Volume:  -     ISSN:  1873-2380     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-6-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier Ltd. All rights reserved.
Affiliation:
Bioengineering Department, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy.
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