Three-dimensional asymmetrical modeling of the mitral valve: a finite element study with dynamic boundaries

Previous computational studies of the normal mitral valve have been limited because they assumed symmetrical modeling and artificial boundary conditions. The study aim was to model the mitral valve complex asymmetrically with three-dimensional (3-D) dynamic boundaries obtained from in-vivo experimental data.

Distance tracings between ultrasound crystals placed in the sheep mitral valve were converted into 3-D coordinates to reconstruct an initial asymmetric mitral model and subsequent dynamic boundary conditions. The non-linear, real-time left ventricular and aortic pressure loads were acquired synchronously. A quasi-static solution was applied over one cardiac cycle.

The mitral valve leaflet stress was heterogeneous. The trigones experienced highest stresses, while the mid-anterior annulus between trigones experienced low stress. High leaflet stress was observed during peak pressure loading. During isovolumic relaxation, the leaflets were highly stretched between the anterolateral trigone and the posteromedial commissure, resulting in a prominent secondary leaflet stress re-increment. This has not been observed previously, as symmetric models with artificial boundary conditions were studied only in the ejection phase.

Here, the first asymmetrical mitral valve model synchronized with 3-D dynamic boundaries and non-linear pressure loadings over the whole cardiac cycle based on in vivo experimental data is described. Despite its limitations, this model provides new insights into the distribution of leaflet stress in the mitral valve.