Role of computational fluid mechanics in the analysis of prosthetic heart valve flow

Tansley, Geoff; Edwards, R.; Gentie, C. R.

doi:10.1007/bf02442261

Cited by 8 publications

(1 citation statement)

References 37 publications

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“…One study 2 suggests that 19.4% of the Bjork-Shiley MHV recipients will suffer some level of embolism, and another 15.3% will suffer bleeding, Flow near the valves and ventricles is unsteady, with high Reynolds numbers within a complex geometry and elastically deforming walls. 8 These properties make both non-invasive experimentation and numerical simulation of blood flow near the heart valves extremely difficult. Nevertheless, plenty of both types of research has been performed in this area, attempting to find the relation between thrombogenic properties of different types of MHVs and their hemodynamic performance.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Fluid-Structure Interaction for Tilting-Disk Mechanical Heart Valve

Aliabadi

2012

42nd AIAA Fluid Dynamics Conference and Exhibit

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In this study a fully coupled implicit fluid-structure-interaction (FSI) scheme has been utilized to investigate the existing tilting-disk mechanical heart valve (MHV) and a proposed design to increase flow quality. Vortex shedding, areas of recirculation with high shear, and high deformation rates are common in the current designs of tilting-disk MHVs, which contribute to the thrombogenicity of these devices. Based on the results of current FSI simulation of the tilting-disk MHV, a new design has been suggested, and comparison of the flow-fields and features important in clot formation are promising. In the proposed design, a number of gaps are inserted on the disk. These gaps are initially closed and subsequently open as the valve rotates toward its fully open position. The gaps stay open during the forward flow and only begin retracting when the leaflet starts moving back to its fully closed position. Inspection of the results reveals that the flow passing through the gaps washes the wakes away from the leaflet as intended and minimizes the separation region. Nomenclature = Angle of rotation with respect to the vertical t = Time M = Moment I = Moment of inertia = Epsilon = Angular acceleration = Shear stress = Viscosity = X component of velocity v = Y component of velocity

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Fluid-Structure Interaction for Tilting-Disk Mechanical Heart Valve

Aliabadi

2012

42nd AIAA Fluid Dynamics Conference and Exhibit

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Measurements of steady flow velocity and turbulent stress downstream from jellyfish and St. Vincent aortic heart valves

1999

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An experimental investigation was conducted to determine the velocity fields, magnitudes of shear stresses, and regions of stagnation of a jellyfish valve and a St. Vincent tilting-disk valve using laser Doppler anemometry (LDA). All experiments were performed in vitro and at steady volumetric flow rates of 15 and 261/min (representing peak systole). The St. Vincent valve flow field was very unsymmetrical in the measurement plane that spanned the major and minor outflow regions of the valve and persisted at least to 1D downstream. For both flow rates tested, a stagnation region was always observed just behind the occluder. The maximum axial velocity was in the major outflow side and reached 2.54 m/s for peak systole flow of 261/min. Moreover, in the immediate vicinity of the valve and for both flow rates tested, turbulence intensities and velocity gradients were higher in the minor outflow region than in the major outflow region. However, as the flow progressed downstream, the opposite was observed, with large peak velocity in the major outflow. The maximum shear stress across the St. Vincent valve occurred in the minor outflow region and increased from 30 to 60N/m 2 as the flow rate increased from 15 to 261/min. In the core of the larger jet, the shear stresses were very small (0-3 N/m2). The flow at the edges of the jellyfish valve membrane, 10mm (0.5D) downstream from the ring valve, consisted of two nearly symmetric jets in the vicinity of the tube wall. The maximum axial velocity in these jet regions increased from 1.7 to 2.5m/s as the flow rates increased from 15 to 261/min. Pressure effects due to the oscillation of the membrane of the jellyfish valve appear to generate high shear stress in the immediate vicinity of the jellyfish valve (0.5D downstream). The values of shear stress were 0-27N/m 2 for a flow of 151/rain and 3-109N/m 2 for a flow of 261/min. However, as the flow progresses downstream, shear stresses decay rapidly and return to the upstream undisturbed level at about 4D downstream, but at a slower rate than the RMS axial velocities. In general, for all operating flow conditions tested here, the jellyfish valve performed better than the St. Vincent valve when velocity and shear stress distributions are compared at locations more than 0.5D downstream from the valve.

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Fluid dynamic study of the moving actuator type total artificial heart by image-processing technique

Kim

Kim²,

Lee

et al. 1994

Med. Biol. Eng. Comput.

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Flow velocity inside the artificial ventricle of a moving actuator type total artificial heart is investigated by the image-processing technique. Optical flow is estimated from two sequential images of flow patterns to find flow-velocity distribution. The region with high velocity inside the artificial ventricle is found from the estimated flow-velocity distribution. Fluid velocity in a simple glass conduit is analysed and can be estimated by calculating optical flow.

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Role of computational fluid mechanics in the analysis of prosthetic heart valve flow

Cited by 8 publications

References 37 publications

Numerical Simulation of Fluid-Structure Interaction for Tilting-Disk Mechanical Heart Valve

Numerical Simulation of Fluid-Structure Interaction for Tilting-Disk Mechanical Heart Valve

Measurements of steady flow velocity and turbulent stress downstream from jellyfish and St. Vincent aortic heart valves

Fluid dynamic study of the moving actuator type total artificial heart by image-processing technique

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