Impact of Mitral Regurgitation on the Flow in a Model of a Left Ventricle.

PURPOSE Mitral regurgitation (MR) is the second most common valve disease in industrialized countries. Despite its high prevalence, little is known about its impact on the flow dynamics in the left ventricle (LV). Because of the interdependence between valvular function and hemodynamics in the heart chambers, an exploration of the dynamics in the LV could lead to a diagnosis of MR. This in vitro study aimed to develop an advanced left heart simulator capable of reproducing several conditions of MR and to evaluate their impact on the LV flow dynamics in terms of flow structures and viscous energy dissipation (VED). METHODS A simulator, previously developed to test mechanical and biological valves, was upgraded with an original anatomically-shaped mitral valve made from a hydrogel. The valve can be used in healthy or pathological configurations. The nature and severity of the disease was controlled by applying specific strain to the chordae. In this study, in addition to a healthy condition, two different severities of MR were investigated: moderate MR and severe MR. Planar time-resolved particle image velocimetry measurements were performed in order to evaluate the velocity field in the LV and the VED induced by each condition. RESULTS Our results showed that MR led to flow disturbances in the LV that were characterized by an increase in mitral inflow velocity and by elevated values of VED. Interestingly VED increased in proportion to the severity of MR and with a dissipation predominating during systole. CONCLUSION Considering these results, the introduction of new parameters based on LV VED could provide crucial information regarding the coupling between the mitral valve and the LV and allow for a better stratification of patients with MR.