Image-Based Computational Blood Dynamic Simulation in Presence of Mitral Valve Regurgitation
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Mitral Valve Regurgitation (MVR) is the formation of a regurgitant flow in the left cardiac atrium due to an incomplete closure of the valve leaflets during the systolic phase. The knowledge of haemodynamic quantities such as velocity and Wall Shear Stresses (WSS) can help the surgeons to better understand the pathology and can be computed by means computational methods. Among different computational models, we focused on Computational Fluid Dynamics (CFD) with imposed motion, where the displacement of the heart walls and valves, coming from kinetic medical images, is prescribed for the whole heartbeat. In particular, for CFD, we considered a LES model for transition to turbulence and the RIIS model to manage the valve dynamics, whereas for imaging, we combined two different cine-MRI acquisitions: a radial sampling to reconstruct the geometries and the dynamics of mitral valve, left atrium and aortic sinus, and a parallel sampling for the left ventricle morphology and displacement. With this image-based CFD model, we compared the haemodynamics of healthy and regurgitant configurations over the whole heartbeat. Our results highlighted that blood flow gave rise to transition to turbulence in the atrium during the ventricular systole and in the ventricle during diastole, and to high systolic WSS in the atrium leading, potentially, to weakening of the atrial walls and to degenerative processes. Moreover, our results were consistent with standard clinical classifications of the causes of MVR.
