Effects of mitral chordae tendineae on the flow in the left heart ventricle

Abstract

In this paper a computational model for the ventricular flow with a mitral valve and modeled chordae tendineae is presented. The results are compared with an analogous case in which the chordae are not included and their presence is replaced by kinematic boundary conditions. The problem is studied using direct numerical simulation of the Navier-Stokes equations, two-way coupled with a structural solver for the ventricle and mitral valve dynamics. An experimental validation of the model is performed by a comparison of the results with a companion dedicated experiment. It is found that the inclusion of the chordae tendineae makes the model self-consistent thus avoiding the use of ad hoc kinematic constraints to mimic their effect. In this way it is possible to simulate the correct system dynamics without user-defined parameters. More in detail, the results have shown that the mitral valve dynamics can be described also without chordae with the help of ad hoc kinematic constrains, whereas the changes produced in the intra-ventricular flow need the explicit consideration of the chordae in the model. On the other hand, the computational load increases owing to the presence of additional structures that, being thin filaments, are also demanding for the spatial resolution requirements. Since the presence of the chordae tendineae produces only specific differences in the overall flow structure, we conclude that their explicit modeling should be limited to those cases in which their presence is unavoidable.

A pipeline for image based intracardiac CFD modeling and application to the evaluation of the PISA method

“…As a result, smooth ventricular geometry, a strong simplification of reality, was used. Indeed, it has been shown in the past that the papillary muscles [23], trabeculae [23] and chordae [24] have an influence on the intracardiac hemodynamics. Finally, as it is difficult to obtain personalized pressure curves for the pulmonary veins inlet and aortic outlet in a clinical setting, population-derived pressure BC was used.…”

Systolic anterior motion in hypertrophic cardiomyopathy: a fluid–structure interaction computational model

“…Since they exert mainly a vertical pulling action, they are mimicked by a kinematic constraint that limits the leaflets vertical displacement (see [10] for more details). This is justified since in a separate study [11] it has been shown that the inclusion of chordae tendineae in the model does not appreciably affect the global dynamics of the intraventricular flow and neither prevent nor determine SAM. It is important to note that our kinematic constraint does not limit in any way the lateral motion of the leaflets that is entirely determined by the fluid/structure interaction as part of the solution.…”

“…The time integration has been performed at constant Courant number CFL = 0.2 with a dynamic time stepping that adjusts during the integration so to keep the CFL constant. For the validation of the code we refer to [10,11] in which two different one-to-one experiments are performed for the validation of the flow inside the ventricle, the structure deformation and the mitral valve dynamics; comparisons of the numerical results and experimental measurements are performed for several quantities like the time-dependent area of the mitral valve, pointwise and two dimensional velocity measurements as well as ventricle deformation and mitral leaflets dynamics.…”

“…In a real left ventricle the chordae tendineae, connecting the leaflet tips with the papillary muscles, are organized in a complex web of filaments that make extremely difficult their precise replica (leaving aside the strong variability among different individuals). Therefore, as already done in [11], we reduce all the chordae to four main bundles: each one is a 'ribbon' with the same material properties as the leaflet tissue, departs from one distal corner of a leaflet and connects directly to the ventricle papillary muscle. As shown in [11] the resulting chorded valve can reproduce the main functionalities of the native mitral valve and, while maintaining the computational cost at an acceptable level, prevents the valve prolapse without any external kinematic constraint.…”

“…Therefore, as already done in [11], we reduce all the chordae to four main bundles: each one is a 'ribbon' with the same material properties as the leaflet tissue, departs from one distal corner of a leaflet and connects directly to the ventricle papillary muscle. As shown in [11] the resulting chorded valve can reproduce the main functionalities of the native mitral valve and, while maintaining the computational cost at an acceptable level, prevents the valve prolapse without any external kinematic constraint. The role of the chordae tendineae in the pathophysiology of HCM is evaluated here by performing a simulation with the same set-up as in Sect.…”