Comparison of the Hinge Flow Fields of Two Bileaflet Mechanical Heart Valves under Aortic and Mitral Conditions

Simon, H.; Leo, Hwa Liang; Carberry, Josie; Yoganathan, Ajit P.

doi:10.1007/s10439-004-7814-5

Cited by 41 publications

(76 citation statements)

References 11 publications

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“…26 The previous study also determined that the shape transition was more significant in inducing blood damage than hinge gap width. Thus, the proposed LBM-EBF numerical method has been validated as suitable for future studies of simulating blood element damage that occurs in BMHV flows.…”

Section: Discussionmentioning

confidence: 95%

“…The fluid flow results using the LBM-EBF method are compared to previous experimental and numerical studies 25,26 of flow through the same hinge designs. Figures 7 and 8 show the leakage exit flow patterns for each of the three simulated hinge flows.…”

Section: Discussionmentioning

confidence: 99%

“…1b) between the leaflet ear and hinge recess could result in the washout of blood elements from the hinge region, thus reducing thromboembolic complications. The hinge flow dynamics under aortic pulsatile conditions was later investigated using 2D LDV by Simon et al 26 It was found that although flow fields were qualitatively similar for the two hinge designs, higher velocities and higher Reynolds shear stresses were consistently found in the CM valve when compared to the SJM valve. This is further confirmation that the hinge geometry is a key parameter in influencing hemolysis, platelet activation, and thrombus formation.…”

Section: Introductionmentioning

confidence: 96%

“…Moreover, most experimental studies suffer from low spatial resolution and limitation to two-dimensional velocity data acquisition. 11,12,15,20,26 Leo 19 acquired two-dimensional Laser Doppler Velocimetry (LDV) velocity data in the hinge region of SJM and CM valves, placed in the mitral position, under static leakage flow conditions. It was determined in this study that a larger hinge gap width (see Fig.…”

Section: Introductionmentioning

confidence: 99%

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A Numerical Investigation of Blood Damage in the Hinge Area of Aortic Bileaflet Mechanical Heart Valves During the Leakage Phase

Yun

Simon

et al. 2012

Ann Biomed Eng

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Previous experimental and numerical blood studies have shown that high shear stress levels, long exposure times to these shear stresses, and flow recirculation promote thromboembolism. Artificial heart valves, in particular bileaflet mechanical heart valves (BMHVs), are prone to developing thromboembolic complications. These complications often form at the hinge regions of BMHVs and the associated geometry has been shown to affect the local flow dynamics and the associated thrombus formation. However, to date no study has focused on simulating the motion of realistically modeled blood elements within the hinge region to numerically estimate the hinge-related blood damage. Consequently, this study aims at (a) simulating the motion of realistically modeled platelets during the leakage (mid-diastole) phase in different BMHV hinge designs placed in the aortic position and (b) quantitatively comparing the blood damage associated with different designs. Three designs are investigated to assess the effects of hinge geometry and dimensions: a 23 mm St. Jude Medical Regent™ valve hinge with two different gap distances between the leaflet ear and hinge recess; and a 23 mm CarboMedics (CM) aortic valve hinge. The recently developed lattice-Boltzmann method with external boundary force method is used to simulate the hinge flow and capture the dynamics and surface shear stresses of individual platelets. A blood damage index (BDI) value is then estimated based on a linear shear stress-exposure time BDI model. The velocity boundary conditions are obtained from previous 3D large-scale simulations of the hinge flow fields. The trajectories of the blood elements in the hinge region are found to be qualitatively similar for all three hinges, but the shear stresses experienced by individual platelets are higher for the CM hinge design, leading to a higher BDI. The results of this study are also shown to be in good agreement with previous studies, thus validating the numerical method for future research in BMHV flows. This study provides a general numerical tool to optimize the hinge design based on both hemodynamic and thromboembolic performance.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Numerical Investigation of Blood Damage in the Hinge Area of Aortic Bileaflet Mechanical Heart Valves During the Leakage Phase

Yun

Simon

et al. 2012

Ann Biomed Eng

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“…Platelet activation and thrombus formation is reported to occur due to the leakage flow in the hinge region and much previous research has concentrated on this aspect. 21,27,39,53 The dimension of the hinge region is two orders of magnitude lower than the valve dimension and will need to be considered in the computational analysis.…”

Section: Limitations Of the Studymentioning

confidence: 99%

Two-Dimensional Dynamic Simulation of Platelet Activation During Mechanical Heart Valve Closure

et al. 2006

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A major drawback in the operation of mechanical heart valve prostheses is thrombus formation in the near valve region. Detailed flow analysis in this region during the valve closure phase is of interest in understanding the relationship between shear stress and platelet activation. A fixed-grid Cartesian mesh flow solver is used to simulate the blood flow through a bi-leaflet mechanical valve employing a two-dimensional geometry of the leaflet with a pivot point representing the hinge region. A local mesh refinement algorithm allows efficient and fast flow computations with mesh adaptation based on the gradients of the flow field in the leaflet-housing gap at the instant of valve closure. Leaflet motion is calculated dynamically based on the fluid forces acting on it employing a fluid-structure interaction algorithm. Platelets are modeled and tracked as point particles by a Lagrangian particle tracking method which incorporates the hemodynamic forces on the particles. A platelet activation model is included to predict regions which are prone to platelet activation. Closure time of the leaflet is validated against experimental studies. Results show that the orientation of the jet flow through the gap between the housing and the leaflet causes the boundary layer from the valve housing to be drawn in by the shear layer separating from the leaflet. The interaction between the separating shear layers is seen to cause a region of intensely rotating flow with high shear stress and high residence time of particles leading to high likelihood of platelet activation in that region.

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Effect of Cardiac Devices and Surgery on Vortex Formation

Kheradvar

Pedrizzetti

2011

Vortex Formation in the Cardiovascular System

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Comparison of the Hinge Flow Fields of Two Bileaflet Mechanical Heart Valves under Aortic and Mitral Conditions

Cited by 41 publications

References 11 publications

A Numerical Investigation of Blood Damage in the Hinge Area of Aortic Bileaflet Mechanical Heart Valves During the Leakage Phase

A Numerical Investigation of Blood Damage in the Hinge Area of Aortic Bileaflet Mechanical Heart Valves During the Leakage Phase

Two-Dimensional Dynamic Simulation of Platelet Activation During Mechanical Heart Valve Closure

Effect of Cardiac Devices and Surgery on Vortex Formation

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