Network-based study of Lagrangian trajectories to highlight the effect of bioprosthetic mitral valve oreintation

During the ventricular diastolic phase, the blood flowing through the mitral valve preserves its kinetic energy by forming a large vortex filling almost the whole left ventricle. This vortical structure, then, redirects the blood towards the aorta for the ejection phase. In the presence of mitral valve disease, valve replacement with a bioprosthetic valve becomes an option for symptomatic patients. Surely, the orientation of the implanted bioprosthetic valve with respect to the ventricular apex will affect the energy-preserving behavior of blood transport. Therefore, this in vitro study investigates the effect of three different orientations of valve implantations on ventricular fluid transport. Planar time-resolved particle image velocimetry is used to measure the instantaneous velocity fields at several heart rates. Then, using a network-based analysis of Lagrangian trajectories we reveal the interventricular blood transport mechanism and how it is affected by the orientation of the valve. Also, by using a spectral analysis of the network, we reveal the major transport clusters in the flow field. Finally, our study highlights the overlap between the identified clusters and the Lagrangian coherent structures in the flow as extracted using finite-time Lyapunov exponents.