A sharp interface fluid-structure interaction model for bioprosthetic heart valve dynamics.

摘要

To improve the understanding of bioprosthetic heart valve failure, it is necessary to develop an advanced computer model that incorporates the dynamics of the valve leaflet and surrounding blood under physiologic conditions. Valve leaflets are complex geometries and undergo rapid deformation. Their motion affects---and is affected by---the surrounding blood. This two-way coupling necessitates a robust algorithm in order to overcome numerical stiffness, convergence challenges, and stability issues.;A locally refined Cartesian mesh, sharp interface method has been developed for the solution of flows interacting with moving bodies. In the structural domain, the valve leaflet is represented in a Lagrangian fashion and moves based on its experimentally determined material properties. In computing leaflet motion, the anisotropic, nonlinear material properties of the valve leaflet are incorporated using a finite element solver, which calculates the leaflet deformation and stresses based on the stress in the surrounding fluid.;A fluid-structure interaction algorithm has been developed which enables full two-way coupling in a stable fashion. A strongly-coupled, partitioned approach is used in which subiterations of the fluid and structure solutions are performed at each time step. During the subiterations, the leaflet motion is used as a boundary condition on the fluid, and the fluid stresses act as a boundary condition on the leaflet. In this way, continuity is ensured and two-way coupling is achieved. The simulation has been validated with several benchmark results.;Previous FSI approaches for valve simulations have faced significant challenges and have in most cases been limited to non-physiologic conditions with coarse meshes. The current approach has overcome these challenges, so that a full FSI solution is achieved using physiologic Reynolds numbers, realistic material properties, highly resolved grids, and a dynamic simulation. By fully coupling the motion of the valve with that of the surrounding blood, a solution is available that can more accurately predict leaflet deformation and stresses throughout the cardiac cycle. The simulation can be potentially employed in the understanding of the complex dynamics of the native and prosthetic heart valves and the effect of mechanical stresses on valve failure.