Fluid Mechanical Analysis at Closure of the On-X Mechanical Heart Valve

2007 ◽  
Author(s):  
Christopher M. Haggerty ◽  
Luke H. Herbertson ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Shear Stresses ◽  
Single Shot ◽  
Complex Flow ◽  
Mitral Position ◽  
Valve Housing ◽  
The Impact

Three-dimensional laser Doppler velocimetry (LDV) was used to characterize the flow created by the On-X bileaflet mechanical heart valve (MHV) manufactured by Medical Carbon Research Institute (MCRI), Inc. (Austin, TX). The valve was mounted into a pneumatically driven single-shot chamber in the mitral position such that only the closure dynamics were simulated. Measurements taken 2 mm proximal to the valve housing showed a peak velocity of 1.8 m/s and maximum Reynolds Shear Stresses (RSS) of 17,500 dynes/cm2, which were found along the centerline of the valve in the hinge region 2 ms after valve closure. The large velocity and RSS gradients denote the presence of complex flow structures. These results provide an initial basis for understanding the impact of valve geometry on hemolysis and thrombosis associated with the On-X MHV.

scholarly journals Stereoscopic PIV of Steady Flow Through a Bileaflet Mechanical Heart Valve

2008 ◽  
Author(s):  
C. Hutchison ◽  
P. E. Sullivan ◽  
C. R. Ethier
Keyword(s):  
Steady Flow ◽  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Shear Stresses ◽  
Stereoscopic Piv ◽  
Bileaflet Mechanical Heart Valve ◽  
Component Particle

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.

Static and Dynamic Stresses during Valve Closure of a Bileaflet Mechanical Heart Valve Prosthesis

1991 ◽  
Vol 14 (12) ◽  
pp. 781-788 ◽  
Author(s):  
T.H. Chiang ◽  
H. Lam ◽  
R. Quijano ◽  
R. Donham ◽  
P. Gilliam ◽  
...  
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Heart Valve Prosthesis ◽  
Valve Prosthesis ◽  
Valve Closure ◽  
Element Analysis ◽  
Dynamic Stresses ◽  
Magnitude Distribution ◽  
Bileaflet Mechanical Heart Valve ◽  
The Impact

The effect of contact geometry and component compliance on the magnitude, distribution, and state of various types of stresses on a bileaflet mechanical heart valve prosthesis during valve closure was analyzed using an Edwards-Duromedics™ mitral valve as example. Static and dynamic stresses developing on both the leaflet and pivot ball during valve closure were modeled using finite element analysis (FEA). Uniform contact between the leaflet and housing as well as between the pivot ball and pivot slot can significantly reduce both static and dynamic stresses around the contact area. The level of the dynamic flexural stresses can be an order of magnitude higher than that of the static stresses. When both the radial and axial compliance of the housing are taken into consideration, peak dynamic stress was more than 40% less than that generated through the impact between a moving leaflet and a non-compliant rigid housing.

scholarly journals Hemodynamic Performance of Dysfunctional Prosthetic Heart Valve with the Concomitant Presence of Subaortic Stenosis: In Silico Study

2020 ◽  
Vol 7 (3) ◽  
pp. 90
Author(s):  
Othman Smadi ◽  
Anas Abdelkarim ◽  
Samer Awad ◽  
Thakir D. Almomani
Keyword(s):  
Early Detection ◽  
Heart Valve ◽  
Heart Valves ◽  
Cfd Simulation ◽  
Treatment Plan ◽  
Mechanical Heart Valve ◽  
Prosthetic Heart Valve ◽  
Subaortic Stenosis ◽  
Prosthetic Heart Valves ◽  
The Impact

The prosthetic heart valve is vulnerable to dysfunction after surgery, thus a frequent assessment is required. Doppler electrocardiography and its quantitative parameters are commonly used to assess the performance of the prosthetic heart valves and provide detailed information on the interaction between the heart chambers and related prosthetic valves, allowing early detection of complications. However, in the case of the presence of subaortic stenosis, the accuracy of Doppler has not been fully investigated in previous studies and guidelines. Therefore, it is important to evaluate the accuracy of the parameters in such cases to get early detection, and a proper treatment plan for the patient, at the right time. In the current study, a CFD simulation was performed for the blood flow through a Bileaflet Mechanical Heart Valve (BMHV) with concomitant obstruction in the Left Ventricle Outflow Tract (LVOT). The current study explores the impact of the presence of the subaortic on flow patterns. It also investigates the accuracy of (BMHV) evaluation using Doppler parameters, as proposed in the American Society of Echocardiography (ASE) guidelines.

scholarly journals Forecasting of Surface Currents via Correcting Wind Stress with Assimilation of High-Frequency Radar Data in a Three-Dimensional Model

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Lei Ren ◽  
Stephen Nash ◽  
Michael Hartnett
Keyword(s):  
Data Assimilation ◽  
High Frequency ◽  
Three Dimensional ◽  
Hf Radar ◽  
Surface Velocity ◽  
Shear Stresses ◽  
Surface Currents ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
The Impact

This paper details work in assessing the capability of a hydrodynamic model to forecast surface currents and in applying data assimilation techniques to improve model forecasts. A three-dimensional model Environment Fluid Dynamics Code (EFDC) was forced with tidal boundary data and onshore wind data, and so forth. Surface current data from a high-frequency (HF) radar system in Galway Bay were used for model intercomparisons and as a source for data assimilation. The impact of bottom roughness was also investigated. Having developed a “good” water circulation model the authors sought to improve its forecasting ability through correcting wind shear stress boundary conditions. The differences in surface velocity components between HF radar measurements and model output were calculated and used to correct surface shear stresses. Moreover, data assimilation cycle lengths were examined to extend the improvements of surface current’s patterns during forecasting period, especially for north-south velocity component. The influence of data assimilation in model forecasting was assessed using a Data Assimilation Skill Score (DASS). Positive magnitude of DASS indicated that both velocity components were considerably improved during forecasting period. Additionally, the improvements of RMSE for vector direction over domain were significant compared with the “free run.”

NUMERICAL SIMULATION OF 3D FLUID-STRUCTURE INTERACTION USING AN IMMERSED MEMBRANE METHOD

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1447-1450 ◽  
Author(s):  
G. H. XIA ◽  
Y. ZHAO ◽  
J. H. YEO
Keyword(s):  
Numerical Simulation ◽  
Heart Valve ◽  
Fluid Structure Interaction ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Membrane Method ◽  
Interaction Phenomena

In this paper, an immersed membrane method (IMM) is proposed for the simulation of three-dimensional (3D) fluid-structure interaction phenomena in a mechanical heart valve (MHV).

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

2010 ◽  
Vol 132 (11) ◽  
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.

Physiological Flow Studies in Exact-Replica Atherosclerotic Carotid Bifurcations

2003 ◽  
Author(s):  
J. Bale-Glickman ◽  
K. Selby ◽  
D. Saloner ◽  
O¨. Savas¸
Keyword(s):  
Chaotic Behavior ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
Shear Stresses ◽  
Multiple Sources ◽  
Complex Flow ◽  
Physiological Flow ◽  
Image Velocimetry ◽  
Recirculation Zones

Some results from a series of physiological flow experiments in a model of an atherosclerotic carotid bifurcation are presented. The flow model exactly replicates the lumen of the plaque excised intact from a patient with severe carotid atherosclerosis. Flow visualization (FV) and particle image velocimetry (PIV) are employed as the tools for this study. The complex internal geometry of the diseased artery combined with the pulsatile input flows gives rise to complex flow patterns. The flow fields are highly three-dimensional and chaotic with details varying from cycle to cycle. These flow patterns also include internal jets, three-dimensional shear layers, numerous separation/recirculation zones and stagnation lines. The vorticity and streamline maps confirm this complex and three-dimensional nature of the flow. Planar streamline maps show the three-dimensional flow by the multiple sources/sinks throughout the model. Wall shear stresses (WSS) are estimated to range form about −7 Pa to 34 Pa at the stenotic neck over time with the peak at peak systolic. These WSS also exhibit chaotic behavior during pulsatile flow cycles.

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