Mitral regurgitation (MR) is the second mostcommon valve disease in industrialized countries. Despite itshigh prevalence, little is known about its impact on the flowdynamics in the left ventricle (LV). Because of the interde-pendence between valvular function and hemodynamics inthe heart chambers, an exploration of the dynamics in the LVcould lead to a diagnosis of MR. Thisin vitrostudy aimed todevelop an advanced left heart simulator capable of repro-ducing several conditions of MR and to evaluate their impacton the LV flow dynamics in terms of flow structures andviscous energy dissipation (VED).Methods—A simulator, previously developed to test mechan-ical and biological valves, was upgraded with an originalanatomically-shaped mitral valve made from a hydrogel. Thevalve can be used in healthy or pathological configurations.The nature and severity of the disease was controlled byapplying specific strain to the chordae. In this study, inaddition to a healthy condition, two different severities ofMR were investigated: moderate MR and severe MR. Planartime-resolved particle image velocimetry measurements wereperformed in order to evaluate the velocity field in the LVand the VED induced by each condition.Results—Our results showed that MR led to flow distur-bances in the LV that were characterized by an increase inmitral inflow velocity and by elevated values of VED.Interestingly VED increased in proportion to the severityof MR and with a dissipation predominating during systole.Conclusion—Considering these results, the introduction ofnew parameters based on LV VED could provide crucialinformation regarding the coupling between the mitral valveand the LV and allow for a better stratification of patientswith