Non-linear fluid-coupled computational model of the mitral valve.
OBJECTIVE
The dynamics of the mitral valve result from the synergy of left heart geometry, local blood flow and tissue integrity. Herein is presented the first coupled fluid-structure computational model of the mitral valve in which valvular kinematics result from the interaction of local blood flow and a continuum representation of valvular microstructure.


METHODS
The diastolic geometry of the mitral valve was assembled from previously published experimental data. Anterior and posterior leaflets were modeled as networks of entangled collagen fibers, embedded in an isotropic matrix. The resulting non-linear continuum description of mitral tissue was implemented in a three-dimensional membrane formulation. Chordal tension-only behavior was defined from experimental tensile tests. The computational model considered the valve immersed in a domain of Newtonian blood, with an experimentally determined viscosity corresponding to a shear rate of 180 s(-1) at 37 degrees C. Ventricular and atrial pressure curves were applied to ventricular and atrial surfaces of the blood domain.


RESULTS
Peak closing flow and volume were 51 ml/s and 1.17 ml, respectively. Papillary muscle force ranged dynamically between 0.0 and 2.6 N. Acoustic pressure (RMS) was found to be 3.3 Pa, with a peak frequency of 72 Hz at 0.064 s from the onset of systole. Model predictions showed excellent agreement with available transmitral flow, papillary force and first heart sound (S1) acoustic data.


CONCLUSIONS
The addition of blood flow and an experimentally driven microstructural description of mitral tissue represent a significant advance in computational studies of the mitral valve. This model will be the foundation for future computational studies on the effect of pathophysiological tissue alterations on mitral valve competence.
Department of Bioengineering, University of Washington, Seattle, Washington, USA.
Daniel R
DR
Einstein
Karyn S
KS
Kunzelman
Per G
PG
Reinhall
Mark A
MA
Nicosia
Richard P
RP
Cochran
D000465:Algorithms; D000818:Animals; D016279:Atrial Function, Left / Q000502:physiology; D001696:Biomechanical Phenomena; D001790:Blood Physiological Phenomena; D001809:Blood Viscosity / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D002306:Cardiac Volume / Q000502:physiology; D002815:Chordae Tendineae / Q000502:physiology; D003094:Collagen; D003198:Computer Simulation; D003971:Diastole / Q000502:physiology; D006347:Heart Sounds / Q000502:physiology; D021621:Imaging, Three-Dimensional; D008943:Mitral Valve / Q000033:anatomy & histology / Q000502:physiology*; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D010210:Papillary Muscles / Q000502:physiology; D012212:Rheology; D012756:Sheep; D016277:Ventricular Function, Left / Q000502:physiology; D017725:Ventricular Pressure / Q000502:physiology
D003094:Collagen