Turbulent blood dynamics in the left heart in the presence of mitral regurgitation: a computational study based on multi-series cine-MRI

Abstract

In this work, we performed a computational image-based study of blood dynamics in the whole left heart, both in a healthy subject and in a patient with mitral valve regurgitation. We elaborated multi-series cine-MRI with the aim of reconstructing the geometry and the corresponding motion of left ventricle, left atrium, mitral and aortic valves, and aortic root of the subjects. This allowed us to prescribe such motion to computational blood dynamics simulations where, for the first time, the whole left heart motion of the subject is considered, allowing us to obtain reliable subject-specific information. The final aim is to investigate and compare between the subjects the occurrence of turbulence and the risk of hemolysis and of thrombi formation. In particular, we modeled blood with the Navier–Stokes equations in the arbitrary Lagrangian–Eulerian framework, with a large eddy simulation model to describe the transition to turbulence and a resistive method to manage the valve dynamics, and we used a finite element discretization implemented in an in-house code for the numerical solution.

Image-based computational fluid dynamics to compare two mitral valve reparative techniques for the prolapse

“…Geometric and dynamic data taken from [24]. A: Two views of the geometries and magnitude of the LH displacement , i = 1, …, 30, at the begin of systole t1 (closed mitral valve), end systole ( t ES ) (closed mitral valve), the instant t2 of maximum valve opening (peak of flow rate during E-wave), the instant t3 of maximum ventricular flow rate during diastasis (i.e.…”

“…For case H we have also at disposal cine-MRI images of the mitral valve consisting in 30 frames per heartbeat acquired following the ad hoc protocol proposed in [32] and based on a radial sampling, which are here reconstructed for the first time. Specifically, we reconstructed the geometries and the displacement , i = 1, …, 30, at all the frames, employing the method proposed in [24, 32] (see the Results Section). Furthermore, for each of the two operated cases (N and R), new cine-MRI images of the mitral valve, consisting in 30 acquisitions per heartbeat, were provided.…”

“…The choice of using a DIB-CFD model is motivated by the availability of time-resolved cine-MRI images of two repaired mitral valves together with the left heart wall motion. This allows us to focus on and compare hemodynamic quantities such as velocity, pressure, Wall Shear Stresses (WSS), and turbulence [24][25][26][27][28]. Specifically, we reconstructed three different mitral valves (one healthy and two operated with the two techniques) geometries and motion, and we created three different virtual scenarios where the mitral valves are inserted in the same healthy ventricular geometry and motion, supposed to be the same for the three cases.…”

“…The choice of using a DIB-CFD model is motivated by the availability of time-resolved cine-MRI images of two repaired mitral valves together with the left heart wall motion. This allows us to focus on and compare hemodynamic quantities such as velocity, pressure, Wall Shear Stresses (WSS), and turbulence [24–28].…”

Cardiovascular fluid dynamics: a journey through our circulation

“…As mitral valve regurgitation worsens, the heart must work harder to pump blood to the body, leading to a progressive increase in left ventricle volume with normalization of wall stress. In terms of the fluid dynamics, large-scale flow recirculation, smaller vortices scattered throughout the left ventricle and the presence of a regurgitant jet which promotes increased turbulence in left ventricle have been observed in patients with mitral regurgitation (Al-Wakeel et al 2015;Bennati et al 2023).…”