Effects of VAD Placement on 3D Fluid Flow in a Patient Specific Numerical Model of the Left Ventricle with Ischemic Heart Failure

Abstract

This paper focuses on the interaction between a generic ventricular assist device (VAD) system and the three dimensional flow structure in a pathological left ventricle (LV). The MRI derived geometry motion data of the ventricular endothelial wall has been used as boundary condition for a three dimensional CFD model incorporating the placement of a VAD between the ventricular apex and the ascending aorta. In a first step, the pump action is implemented by simple momentum source terms, which is yet a placeholder for an arbitrary realistic pump system in future work. A two element circulatory system model is adjusted to physiological conditions and serves as an adaptive pressure boundary condition representing the capacity and resistance of the arterial circulatory system. The heart valves are modeled two dimensionally with a projected, realistic opening area. The computational model therefore accounts on the one hand for complex pressure flow interaction in time, like lumped parameter models do. On the other hand, the detailed three dimensional fluid flow structure is solved to analyze the effects of pump action on intra ventricular, intra aortic and pump cannula flow patterns. First simulation results indicate significant changes in the flow structure and therefore show relevance for the estimation of flow induced blood trauma caused directly and indirectly by VAD placement.