Three-dimensional study of the effect of two leaflet opening angles on the time-dependent flow through a bileaflet mechanical heart valve

Each year over 180,000 mechanical heart valves are implanted worldwide, with the bileaflet mechanical heart valve (BiMHV) accounting for approximately 85% of all valve replacements [1,2]. Although much improved from previous valve designs, aortic BiMHV design is far from ideal, and serious complications such as thromboembolism and hemolysis often result. Hemolysis and platelet activation are thought to be caused by turbulent Reynolds shear stresses in the flow [1]. Numerous previous studies have examined aortic BiMHV flow using LDA and two component Particle Image Velocimetry (PIV), and have shown the flow to be complex and three-dimensional [3,4]. Stereoscopic PIV (SPIV) can obtain all three velocity components on a flow plane, and hence has the potential to provide better understanding of three dimensional flow characteristics. The objective of the current study was to use SPIV to measure steady flow, including turbulence properties, downstream of a BiMHV in a modeled aorta. The resulting dataset will be useful for CFD model validation, and the intent is to make it publicly available.

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An Initial Parametric Study on Fluid Flow Through Bileaflet Mechanical Heart Valves Using Computational Fluid Dynamics

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1243/pime_proc_1994_208_267_02 ◽

1994 ◽

Vol 208 (2) ◽

pp. 63-72 ◽

Cited By ~ 23

Author(s):

M J King ◽

T David ◽

J Fisher

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Heart Valve ◽

Heart Valves ◽

Mechanical Heart Valve ◽

Volumetric Flow Rate ◽

Flow Fields ◽

Opening Angle ◽

Bileaflet Mechanical Heart Valve ◽

Flow Through

The effect of leaflet opening angle on flow through a bileaflet mechanical heart valve has been investigated using computational fluid dynamics (CFD). Steady state, laminar flow for a Newtonian fluid at a Reynolds number of 1500 was used in the two-dimensional model of the valve, ventricle, sinus and aorta. This computational model was verified using one-dimensional laser Doppler velocimetry (LDV). Although marked differences in the flow fields and energy dissipation of the jets downstream of the valve were found between the CFD predictions and the three-dimensional experimental model, both methods showed similar trends in the changes of the flow fields as the leaflet opening angle was altered. As the opening angle increased the area of recirculating fluid downstream of the leaflets, the pressure drop across the valve and the volumetric flow rate through the outer orifice decreased. For opening angles greater than 80° the jet through the outer orifice recombined with the central jet downstream of the leaflet; for an opening angle of 78° the jet through the outer orifice impinged on the aortic wall before recombining with the central jet. This study suggests that the opening angle has a marked effect on the flow downstream of the bileaflet mechanical heart valve and that valves with opening angles greater than 80° are preferable.

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Numerical Study on the Pulsatile Blood Flow through a Bileaflet Mechanical Heart Valve and Leaflet Behavior Using Fluid-Structure Interaction (FSI) Technique

Journal of Fluid Machinery ◽

10.5293/kfma.2004.7.3.014 ◽

2004 ◽

Vol 7 (3) ◽

pp. 14-22

Author(s):

Choeng-Ryul Choi ◽

Chang-Nyung Kim

Keyword(s):

Blood Flow ◽

Heart Valve ◽

Numerical Study ◽

Fluid Structure Interaction ◽

Mechanical Heart Valve ◽

Pulsatile Blood Flow ◽

Fluid Structure ◽

Structure Interaction ◽

Bileaflet Mechanical Heart Valve ◽

Flow Through

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The Effect of Implantation Orientation of a Bileaflet Mechanical Heart Valve on Kinematics and Hemodynamics in an Anatomic Aorta

Journal of Biomechanical Engineering ◽

10.1115/1.4002491 ◽

2010 ◽

Vol 132 (11) ◽

Cited By ~ 36

Author(s):

Iman Borazjani ◽

Fotis Sotiropoulos

Keyword(s):

Heart Valve ◽

Mechanical Heart Valve ◽

Three Dimensional ◽

Symmetry Plane ◽

Convergence Acceleration ◽

Immersed Boundary ◽

Strongly Coupled ◽

Bileaflet Mechanical Heart Valve ◽

Acceleration Technique ◽

Magnetic Resonance Imaging Mri

We carry out three-dimensional high-resolution numerical simulations of a bileaflet mechanical heart valve under physiologic pulsatile flow conditions implanted at different orientations in an anatomic aorta obtained from magnetic resonance imaging (MRI) of a volunteer. We use the extensively validated for heart valve flow curvilinear-immersed boundary (CURVIB) fluid-structure interaction (FSI) solver in which the empty aorta is discretized with a curvilinear, aorta-conforming grid while the valve is handled as an immersed boundary. The motion of the valve leaflets are calculated through a strongly coupled FSI algorithm implemented in conjunction with the Aitken convergence acceleration technique. We perform simulations for three valve orientations, which differ from each other by 45 deg and compare the results in terms of leaflet motion and flow field. We show that the valve implanted symmetrically relative to the symmetry plane of the ascending aorta curvature exhibits the smallest overall asymmetry in the motion of its two leaflets and lowest rebound during closure. Consequently, we hypothesize that this orientation is beneficial to reduce the chance of intermittent regurgitation. Furthermore, we find that the valve orientation does not significantly affect the shear stress distribution in the aortic lumen, which is in agreement with previous studies.

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