Role of Mitral Inflow and Wall Motion in the Left Ventricular Vortices

Recent studies have highlighted the importance of evaluating the vortical structure of blood flow in the left ventricle (LV) as a promising approach to assess LV efficiency and understand the flow mechanisms that drive the progression of cardiac diseases. LV vortices, characterized by swirling flows of particles around a central axis, play a crucial role in maintaining the momentum and kinetic energy of diastolic flow and in guiding blood flow toward the aortic outflow tract during systole. Despite the recognized significance of these vortices, a comprehensive understanding of the mechanisms underlying their formation remains underdeveloped. In this study, we utilized a patient-specific fluid-structure interaction (FSI) modeling framework, leveraging phase-contrast magnetic resonance imaging (PC-MRI) data, to investigate the influence of mitral inflow rate and endocardial wall motion on LV vortices. We synthetically modulated the mitral inflow rate and endocardial wall motion in our baseline model and studied their effects on LV vortices. Our results demonstrated that alterations in mitral flow had a more pronounced impact on the LV vorticity magnitude, averaged over the cardiac cycle, compared to changes in endocardial wall motion. Enhancing and attenuating mitral inflow by 20% resulted in volumetric vorticity magnitude variations of +22.45% and -23.68%, respectively, whereas similar parametric modifications to endocardial wall motion led to comparatively smaller changes of +3.68% and - 3.85%, respectively. Furthermore, changes in wall motion had a more significant impact on systolic vortices than on diastolic vortices. These findings highlight the need for further studies that incorporate patient-specific physiological and pathological boundary conditions to fully understand the interplay between endocardial wall motion, mitral inflow, and intraventricular vortex dynamics.