title: On the effects of leaflet microstructure and constitutive model on the closing behavior of the mitral valve.
abstract: Recent long-term studies showed an unsatisfactory recurrence rate of severe mitral regurgitation 3-5 years after surgical repair, suggesting that excessive tissue stresses and the resulting strain-induced tissue failure are potential etiological factors controlling the success of surgical repair for treating mitral valve (MV) diseases. We hypothesized that restoring normal MV tissue stresses in MV repair techniques would ultimately lead to improved repair durability through the restoration of MV normal homeostatic state. Therefore, we developed a micro- and macro- anatomically accurate MV finite element model by incorporating actual fiber microstructural architecture and a realistic structure-based constitutive model. We investigated MV closing behaviors, with extensive in vitro data used for validating the proposed model. Comparative and parametric studies were conducted to identify essential model fidelity and information for achieving desirable accuracy. More importantly, for the first time, the interrelationship between the local fiber ensemble behavior and the organ-level MV closing behavior was investigated using a computational simulation. These novel results indicated not only the appropriate parameter ranges, but also the importance of the microstructural tuning (i.e., straightening and re-orientation) of the collagen/elastin fiber networks at the macroscopic tissue level for facilitating the proper coaptation and natural functioning of the MV apparatus under physiological loading at the organ level. The proposed computational model would serve as a logical first step toward our long-term modeling goal-facilitating simulation-guided design of optimal surgical repair strategies for treating diseased MVs with significantly enhanced durability.
authors.affiliation: Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin, 201 East 24th Street, 1 University Station C0200, POB 5.236, Austin, TX, 78712, USA.
authors.forename: Chung-Hao
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Cardiovascular Fluid Mechanics Laboratory, Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle NW, Atlanta, GA, 30318, USA.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Rabbah
authors.affiliation: Cardiovascular Fluid Mechanics Laboratory, Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle NW, Atlanta, GA, 30318, USA.
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
authors.affiliation: Gorman Cardiovascular Research Group, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA, 19104, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gorman
authors.affiliation: Gorman Cardiovascular Research Group, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA, 19104, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Gorman
authors.affiliation: W. A. "Tex" Moncrief, Jr. Simulation-Based Engineering Science Chair I, Department of Biomedical Engineering, Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin, 201 East 24th Street, 1 University Station C0200, POB 5.236, Austin, TX, 78712, USA. msacks@ices.utexas.edu.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Sacks
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D019245:Compressive Strength / Q000502:physiology; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D006801:Humans; D008943:Mitral Valve / Q000166:cytology* / Q000502:physiology*; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D012756:Sheep; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology
keywords: Affine fiber kinematics; Image-based FE simulation; In vitro validations; Mapped fiber microstructural architecture; Simplified structural constitutive model