Numerical Modeling of Intraventricular Flow during Diastole after Implantation of BMHV

Abstract

This work presents a numerical simulation of intraventricular flow after the implantation of a bileaflet mechanical heart valve at the mitral position. The left ventricle was simplified conceptually as a truncated prolate spheroid and its motion was prescribed based on that of a healthy subject. The rigid leaflet rotation was driven by the transmitral flow and hence the leaflet dynamics were solved using fluid-structure interaction approach. The simulation results showed that the bileaflet mechanical heart valve at the mitral position behaved similarly to that at the aortic position. Sudden area expansion near the aortic root initiated a clockwise anterior vortex, and the continuous injection of flow through the orifice resulted in further growth of the anterior vortex during diastole, which dominated the intraventricular flow. This flow feature is beneficial to preserving the flow momentum and redirecting the blood flow towards the aortic valve. To the best of our knowledge, this is the first attempt to numerically model intraventricular flow with the mechanical heart valve incorporated at the mitral position using a fluid-structure interaction approach. This study facilitates future patient-specific studies.

Fig 1. Geometry and mesh of the ideal ventricle.

A: anterior leaflet. P: Posterior leaflet.

Fig 2. Plots of (a) ventricular volume, (b)mitral flow velocity, (c) leaflet angular position and (d) leaflet angular velocity during diastole.

T* = t/T. t: flow time. T: cardiac period. Anterior leaflet: dash-dot line. Posterior leaflet: solid line.

Fig 3. Development of out-of-plane vorticity contours during diastole.

(a) T* = 0.05, (b)T* = 0.125, (c)T* = 0.2, (d)T* = 0.25, (e)T* = 0.325, (f)T* = 0.45, (g) T* = 0.55, (h) T* = 0.6. (S1 Video).

Fig 4. Development of planar velocity during diastole.

(a) T* = 0.05, (b)T* = 0.125, (c)T* = 0.2, (d)T* = 0.25, (e)T* = 0.325, (f)T* = 0.45, (g) T* = 0.55, (h) T* = 0.6.

Fig 5. Development of pressure gradient pattern during diastole.

(a) T* = 0.05, (b)T* = 0.125, (c)T* = 0.2, (d)T* = 0.25, (e)T* = 0.325, (f)T* = 0.45, (g) T* = 0.55, (h) T* = 0.6.

Fig 6. Pressure difference ΔP(t*) during diastole.