Impulsive-Motion Model for Computing the Closing Motion of Mechanical Heart-Valve Leaflets

Abstract

The speed of mechanical heart-valve leaflets is known to be an important quantity for predicting cavitation, yet no simple computational means exists for predicting the leaflet speed. In this study, a model for simulating the motion of heart-valve leaflets in rigid test systems is presented. The input for the simulations is the ventricular pressure trace, readily measured in heart-valve tests. The model is based upon an impulsive-motion approximation, wherein the motion within the system is produced by rapid acceleration at the boundary, e.g., by a moving piston. A set of quasisteady, linear equations for the pressure field that are decoupled from the leaflet equation of motion is derived. The pressure field and leaflet moment are computed without the need to treat moving boundaries. Model predictions of closing time compared favorably with those measured in a 1994 cavitation study. Computed values of leaflet tip speed were also compared with those of a previous study, at the same value of average pressure slope. The model values were in agreement with measured speeds, given the limitations of using the average pressure slope as a metric for comparison.

Fundamental mechanics of aortic heart valve closure

“…Unfortunately, the computation of this parameter is very difficult although excellent correlation of a simple numerical method, based on a psuedo-steady acoustic scattering approach, with experimental data has been reported by Myers and Porter (2003). As the flow begins to reverse, the occluder will become entrained in the flow and swept to closure.…”

Fluid–Structure-Electrophysiology interaction (FSEI) in the left-heart: A multi-way coupled computational model

“…For example, [6,7] have considered the FSI problem for the flow in a deformable aorta predicting data of clinical interest such as shear stress, tissue deformations, pressure waveforms and flow velocities. When also the dynamics of the aortic valve has been considered, the problem has been simplified by integrating only part of the cycle [8], imposing symmetries [9] or resorting to a rigid aortic root [10,11] so as to decrease the computational cost. In some cases, turbulence models have been used to avoid the explicit simulation of the smallest flow scales [12,13] thus reducing substantially the nodes of the computational mesh and allowing for larger integration time steps.…”

Direct numerical simulation of the pulsatile flow through an aortic bileaflet mechanical heart valve

“…Other papers dealing with the fluid-structure interaction refer to simplified geometries or two-dimensional flows (Pedrizzetti & Domenichini 2006. In other studies, only part of the cycle is considered (Myers & Porter 2003) and the numerical simulation imposes symmetries (Cheng, Lai & Chandran 2004) so as to decrease the computational cost. In addition, in the majority of the literature, turbulence models are used to avoid the explicit simulation of the smallest scales (Grigioni et al 2005;Yokoyama et al 2006;Alemu & Bluestein 2007, among many others); this substantially reduces the nodes of the mesh and allows for larger integration time steps, but at the expense of the information on the turbulence fine scales whose accurate description is mandatory for the comprehension of the clinical phenomena mentioned above.…”