LDA Study of the Flow Associated With the Design Differences and Orientations of the Bileaflet Mechanical Prostheses

2000 ◽  
Author(s):  
Toshinosuke Akutsu ◽  
Daiki Higucchi ◽  
Tomohiro Taguchi
Keyword(s):  
Flow Field ◽  
Pulsatile Flow ◽  
Heart Valves ◽  
Flow Fields ◽  
Flow Conditions ◽  
Jude Medical ◽  
Mitral Position ◽  
Highly Sensitive ◽  
Mechanical Prostheses ◽  
Two Component

Abstract Four typical mechanical bileaflet heart valves (St. Jude Medical, Advancing The Standard, Carbomedics, and Jyros valves) have been tested in the mitral position under pulsatile flow conditions. Measurements of velocity and turbulent stresses were conducted at five downstream locations using a sophisticated cardiac simulator in conjunction with a highly sensitive two-component LDA. Comparison of these flow fields associated with the opening and subsequent accelerating phase of the flow revealed similarity and dissimilarity of the flow field associated with the different valve designs and helped established visualizing the effect of the valve designs and orientations on the flow.

Highly resolved pulsatile flows through prosthetic heart valves using the entropic lattice-Boltzmann method

2014 ◽  
Vol 754 ◽  
pp. 122-160 ◽  
Author(s):  
B. Min Yun ◽  
L. P. Dasi ◽  
C. K. Aidun ◽  
A. P. Yoganathan
Keyword(s):  
Lattice Boltzmann Method ◽  
Pulsatile Flow ◽  
Lattice Boltzmann ◽  
Heart Valves ◽  
Prosthetic Heart Valves ◽  
Spatiotemporal Resolution ◽  
Jude Medical ◽  
High Spatiotemporal Resolution ◽  
Flow Through ◽  
Boltzmann Method

AbstractProsthetic heart valves have been widely used to replace diseased or defective native heart valves. Flow through bileaflet mechanical heart valves (BMHVs) have previously demonstrated complex phenomena in the vicinity of the valve owing to the presence of two rigid leaflets. This study aims to accurately capture the complex flow dynamics for pulsatile flow through a 23 mm St Jude Medical (SJM) Regent™ BMHV. The lattice-Boltzmann method (LBM) is used to simulate pulsatile flow through the valve with the inclusion of reverse leakage flow at very high spatiotemporal resolution that can capture fine details in the pulsatile BMHV flow field. For higher-Reynolds-number flows, this high spatiotemporal resolution captures features that have not been observed in previous coarse resolution studies. In addition, the simulations are able to capture with detail the features of leaflet closing and the asymmetric b-datum leakage jet during mid-diastole. Novel flow physics are visualized and discussed along with quantification of turbulent features of this flow, which is made possible by this parallelized numerical method.

Ventricular flow Dynamic past Bileaflet Prosthetic Heart Valves

1995 ◽  
Vol 18 (7) ◽  
pp. 380-391 ◽  
Author(s):  
V. Garitey ◽  
T. Gandelheid ◽  
J. Fuseri ◽  
R. PÉlissier ◽  
R. Rieu
Keyword(s):  
Heart Valves ◽  
Prosthetic Heart Valves ◽  
Septal Wall ◽  
Jude Medical ◽  
Anatomical Position ◽  
Mitral Inflow ◽  
Mitral Position ◽  
Significant Difference ◽  
Axis Parallel ◽  
Cardiovascular Simulator

To characterise hydrodynamic properties of prosthetic heart valves in mitral position, ultrasonic velocity measurements were performed using a cardiovascular simulator. A Duromedics and a Saint-Jude Medical bileaflet heart valve were tested. The Saint-Jude valve was oriented first in an anatomical position, i.e. the tilt axis parallel to the septal wall, and then in an anti-anatomical position. In the anti-anatomical position, from mid diastole to mid systole, two contrarotative vortices are generated in the ventricle by the interaction between the flow directed by the leaflets downstream from the lateral orifices and the ventricular wall motions. In the anatomical position, the mitral flow penetrates the ventricle principally through the lateral orifice proximal to the septal wall, due to the vortex in the atrial chamber. The mitral inflow then circulates along the septal wall to the apex, and produces a large ventricular vortex during systole. In the anatomical position, the Saint-Jude thus provides a better ventricular washout during this phase. The mitral inflow through the Duromedics in the anti-anatomical position produces two contrarotative vortices in the ventricle, but in the opposite sense than downstream the Saint-Jude valve; the flows that penetrate through the lateral orifices are directed to the ventricular walls and then recirculate to the centre of the ventricle, providing a very fluctuating flow near the apex. Thus, a slight difference in valve design produces a significant difference in the ventricular flow fields.

Scale-resolving Simulations of Steady and Pulsatile Flow Through Healthy and Stenotic Heart Valves

2021 ◽  
Author(s):  
Martijn Hoeijmakers ◽  
Valery Morgenthaler ◽  
Marcel Rutten ◽  
Frans van de Vosse
Keyword(s):  
Pressure Drop ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Pulsatile Flow ◽  
Heart Valves ◽  
Energy Levels ◽  
Power Spectra ◽  
Navier Stokes ◽  
Rans Simulations

Abstract Blood-flow downstream of stenotic and healthy aortic valves exhibits intermittent random fluctuations in the velocity field which are associated with turbulence. Such flows warrant the use of computationally demanding scale-resolving models. The aim of this work was to compute and quantify this turbulent flow in healthy and stenotic heart valves for steady and pulsatile flow conditions. Large Eddy Simulations (LES) and Reynolds-Averaged Navier-Stokes (RANS) simulations were used to compute the flow field at inlet Reynolds numbers of 2700 and 5400 for valves with an opening area of 70 mm^2 and 175 mm^2, and their projected orifice-plate type counterparts. Power spectra, and turbulent kinetic energy were quantified on the centerline. Projected geometries exhibited an increased pressure-drop (>90%), and elevated turbulent kinetic energy levels (>150%). Turbulence production was an order of magnitude higher in stenotic heart valves compared to healthy valves. Pulsatile flow stabilizes flow in the acceleration phase, whereas onset of deceleration triggered (healthy valve) or amplified (stenotic valve) turbulence. Simplification of the aortic valve by projecting the orifice area should be avoided in computational fluid dynamics. RANS simulations may be used to predict the transvalvular pressure-drop, but scale-resolving models are recommended when detailed information of the flow field is required.

PULSATILE FLOW FIELDS IN A MODEL OF ABDOMINAL AORTA WITH ITS PERIPHERAL BRANCHES

2003 ◽  
Vol 15 (05) ◽  
pp. 170-178 ◽  
Author(s):  
D. LEE ◽  
J. Y. CHEN
Keyword(s):  
Flow Field ◽  
Steady Flow ◽  
Abdominal Aorta ◽  
Pulsatile Flow ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Computer Code ◽  
Flow Fields ◽  
Dynamic Factors ◽  
Recirculation Zones

In a previous study by the authors, steady flow fields in a model of abdominal aorta with its seven peripheral branches were reported. In the present study, the some aorta model was simulated numerically with a pulsatile inlet waves for both the resting and exercise conditions. The baseline pulsatile flow field was presented in terms of velocity vectors and iso-velocity contours as well as the wall shear stress (WSS) distribution and the recirculation zones. The time-averaged behavior of the flow field represented by the fluid dynamic factors was discussed. The results were consistent with those obtained experimentally and numerically by other investigators. It was also found that under the present conditions, the steady flow behavior could adequately describe the time-averaged behavior of its corresponding pulsatile case, particularly in the regions where convective flow dominated. The present computer code may provide a platform for clinical simulations.

How Do Transcatheter Heart Valves Fit in Mitral Annuloplasty Rings and Which Combination Can be Recommended?

2018 ◽  
Vol 67 (04) ◽  
pp. 257-265
Author(s):  
Roya Ostovar ◽  
Ralf-Uwe Kuehnel ◽  
Michael Erb ◽  
Martin Hartrumpf ◽  
Thomas Claus ◽  
...  
Keyword(s):  
High Speed ◽  
Visual Inspection ◽  
Heart Valves ◽  
Mitral Annuloplasty ◽  
Jude Medical ◽  
Pulse Duplicator ◽  
Round Shape ◽  
Mitral Position ◽  
Transcatheter Heart Valve ◽  
Edwards Sapien

Background Transcatheter heart valve (THV) as valve-in-ring is increasingly used in the mitral position. Semi-rigid rings may serve as a more appropriate scaffold for proper anchoring of a THV as they may change from their oval to a round shape thereby fitting to the implanted THV. Methods One rigid and five semi-rigid rings of four manufacturers, Edwards Physio I and II, Sorin 3D Memo, Medtronic Simulus, and St. Jude Medical (SJM) Saddle and SJM Sequin, with sizes 28 to 36 mm and Edwards Sapien III THV 23, 26, and 29 mm were used. Preevaluation comprised insertion/inflation of the THV into the ring and visual inspection for the paravalvular gap ≥ 4 mm2. Only valves not showing paravalvular gap were then submitted to hemodynamic evaluation with a pulse duplicator. Cusp movement was assessed with a high-speed-camera. Mean transvalvular gradients (TVGs) were measured. Results SJM Saddle ring of all sizes and SJM Sequin ring 34 showed marked gaps combined with all THV sizes, thus not undergoing hemodynamic testing. It was further shown that ring sizes ≥ 36 mm did not allow for a proper fit of even the largest THV into the ring of all the manufacturers and were consequently not hemodynamically evaluated. The 23 mm THV was too small for any ring size. The lowest gradients were achieved with the 26 mm THV in 30 and 32 mm and the 29 mm THV in 32 and 34 mm rings. Conclusion Not all currently available annuloplasty rings are ideal scaffolds for THV placement. It appears that a more proper fit can be achieved with semi-rigid rings than with rigid ones. Note that 23 mm THV appeared to be too small for an adequate anchoring in even the smallest available ring. Thus, 26 mm as well as 29 mm THV fit properly in ring sizes between 28 and 34 mm. Surgeons may consider to choose from those ring brands and sizes which allow for good placement of a THV in view of possible valve degeneration in the later course.

Hydrodynamic Advantages and Disadvantages of Mechanical Bileaflet Valves and Tilting Disc Valves No. 29

1987 ◽  
Vol 16 (2) ◽  
pp. 77-85 ◽  
Author(s):  
R Heiliger
Keyword(s):  
Heart Valves ◽  
Efficiency Index ◽  
Mechanical Heart Valves ◽  
Orifice Area ◽  
Pressure Drops ◽  
Jude Medical ◽  
Advantages And Disadvantages ◽  
Mock Circulation ◽  
Mitral Position ◽  
Bileaflet Valves

In order to determine the effectiveness of mechanical heart valves two different types of mechanical heart valves, three tilting disc valves (BS–SD, BS–CCD, BS–M) and two bileaflet valves (St Jude Medical, Duromedics) with the same size of annulus diameter dA = 29 mm have been investigated in the mitral position of a mock circulation under pulsatile flow conditions. Flow, pressure and orifice area have been measured. Insufficiency, mean orifice area, discharge coefficient, performance index, and efficiency index have been calculated. The investigated tilting disc valves show smaller reflux volume and smaller insufficiency when comparing with the bileaflet valves. The bileaflet valves show higher values of orifice areas—that is to say smaller pressure drops—than the tilting disc valves. The St Jude Medical shows the biggest orifice areas, but also the highest reflux volume and insufficiency. Insufficiency of the Duromedics is slightly higher than that of the tilting disc valves. The orifice area of the Duromedics is bigger than that of the tilting disc valves and smaller than that of the St Jude Medical. The different pivot and the different profile of the disc of the BS–CCD and the BS–M are responsible for the more constant behaviour of the opening of these tilting disc valves when comparing with the BS–SD. Though the bileaflet valves show the better efficiency index, none of the valve types is superior in all hydrodynamic criteria. Both valve types, the bileaflet valves and the tilting disc valves, show different hydrodynamic advantages and disadvantages.

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