An In Vitro Comparative Study of St. Jude Medical and Edwards-Duromedics Bileaflet Valves Using Laser Anemometry

1989 ◽  
Vol 111 (4) ◽  
pp. 298-302 ◽  
Author(s):  
R. Fatemi ◽  
K. B. Chandran
Keyword(s):  
Comparative Study ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Velocity Profiles ◽  
Flow Conditions ◽  
Tilt Axis ◽  
Jude Medical ◽  
Laser Anemometry ◽  
Bileaflet Valves

An in vitro comparative study of St. Jude (SJ) and Edwards-Duromedics (DM) Bileaflet valves was performed under steady and physiological pulsatile flow conditions in an axisymmetric chamber using Laser Doppler Anemometry (LDA). LDA measurements were conducted in two different orientations; in the first orientation, the LDA traverse was perpendicular and, in the second orientation, parallel to the tilt axis of the leaflets. The axial velocities were measured in both orientations at two different locations distal to the valves. The velocity profiles at peak systole show the presence of stronger vortex in the sinus region for flow past SJ valve in the first orientation compared to the DM valve. Velocity profile distal to the SJ valve in second orientation was relatively flat where as for the DM valve, a jet-like flow was present. The differences found in the velocity profiles between the two valves can be attributed to the differences in geometry with thicker leaflets, smaller angle of leaflets opening and the presence of the leaflet curvature for the DM valve. The results obtained in this study do not show any fluid dynamic advantages due to the curved leaflet geometry of the DM valve.

Velocity and Shear Stress Distribution Downstream of Mechanical Heart Valves in Pulsatile Flow

1989 ◽  
Vol 12 (4) ◽  
pp. 261-269 ◽  
Author(s):  
M. Giersiepen ◽  
U. Krause ◽  
E. Knott ◽  
H. Reul ◽  
G. Rau
Keyword(s):  
Shear Stress ◽  
Heart Valves ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
In Vitro Study ◽  
Turbulent Shear ◽  
Momentum Exchange ◽  
Jude Medical ◽  
Turbulent Shear Stress

Ten mechanical valves (TAD 27 mm): Starr-Edwards Silastic Ball, Björk-Shiley Standard, Björk-Shiley Concave-Convex, Björk-Shiley Monostrut, Hall-Kaster (Medtronic-Hall), OmniCarbon, Bicer Val, Sorin, Saint-Jude Medical and Hemex (Duromedics) are investigated in a comparative in vitro study. The velocity and turbulent shear stress profiles of the valves were determined by Laser Doppler anemometry in two different downstream axes within a model aortic root. Depending on the individual valve design, velocity peaks up to 1.5 m/s and turbulent shear stress peaks up to 150 N/m2 were measured during the systolic phase. These shear stress peaks mainly occurred in areas of flow separation and intense momentum exchange. Directly downstream of the valves (measuring axis 0.55.dAorta) turbulent shear stress peaks occurred at peak systole and during the deceleration phase, while in the second measuring axis (1.5.dAorta) turbulence levels were lower. Shear stress levels were high at the borders of the fluid jets. The results are discussed from a fluid-dynamic point of view.

Carbomedics and St. Jude Medical bileaflet valves: an in vitro and in vivo comparison

1992 ◽  
Vol 6 (5) ◽  
pp. 267-271 ◽  
Author(s):  
R JOHNSTON ◽  
N WEERASENA ◽  
M BUTTERFIELD ◽  
J FISHER ◽  
T SPYT
Keyword(s):  
Jude Medical ◽  
Bileaflet Valves

Evaluation of Magnetic Resonance Velocimetry for Steady Flow

1990 ◽  
Vol 112 (4) ◽  
pp. 464-472 ◽  
Author(s):  
D. N. Ku ◽  
C. L. Biancheri ◽  
R. I. Pettigrew ◽  
J. W. Peifer ◽  
C. P. Markou ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Steady Flow ◽  
Laser Doppler Anemometry ◽  
Flow Behavior ◽  
Velocity Profiles ◽  
Secondary Flows ◽  
Whole Body ◽  
Straight Tube ◽  
Flow Conditions ◽  
Wide Range

Whole body magnetic resonance (MR) imaging has recently become an important diagnostic tool for cardiovascular diseases. The technique of magnetic resonance phase velocity encoding allows the quantitative measurement of velocity for an arbitrary component direction. A study was initiated to determine the ability and accuracy of MR velocimetry to measure a wide range of flow conditions including flow separation, three-dimensional secondary flow, high velocity gradients, and turbulence. A steady flow system pumped water doped with manganese chloride through a variety of test sections. Images were produced using gradient echo sequences on test sections including a straight tube, a curved tube, a smoothly converging-diverging nozzle, and an orifice. Magnetic resonance measurements of laminar and turbulent flows were depicted as cross-sectional velocity profiles. MR velocity measurements revealed such flow behavior as spatially varying velocity, recirculation and secondary flows over a wide range of conditions. Comparisons made with published experimental laser Doppler anemometry measurements and theoretical calculations for similar flow conditions revealed excellent accuracy and precision levels. The successful measurement of velocity profiles for a variety of flow conditions and geometries indicate that magnetic resonance imaging is an accurate, non-contacting velocimeter.

In Vitro Hydrodynamics of Four Bileaflet Valves in Mitral Position

2000 ◽  
Vol 8 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Zhong Gang Feng ◽  
Mitsuo Umezu ◽  
Tetsuo Fujimoto ◽  
Toshiya Tsukahara ◽  
Masakazu Nurishi ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Orifice Diameter ◽  
Opening Angle ◽  
Positive Pressure ◽  
Closing Volume ◽  
In Vitro Test ◽  
Jude Medical ◽  
Carbomedics Valve ◽  
Bileaflet Valves

Hydrodynamics of St. Jude Medical, Carbomedics, Advancing The Standard, and On-X bileaflet valves with an annular diameter of 25 mm were obtained using an in-vitro test system. Steady flow studies demonstrated different pressure drops due to differences in valve design, particularly the geometric orifice diameter and the opening angle. The On-X valve produced the least pressure drop, whereas the Carbomedics valve had the greatest pressure drop. In pulsatile flow experiments, the On-X and St. Jude Medical valves consistently produced the lowest mean positive pressure gradients, while the Carbomedics valve had the highest gradients. In spite of its parallel leaflets design, the On-X valve showed a closing volume as small as that of Carbomedics valve. The results indicate that a larger orifice diameter and greater opening angle can significantly reduce transvalvular pressure loss. This study also demonstrated that attempts to improve the hydrodynamic efficacy of the On-X valve were successful in reducing the pressure gradient as well as maintaining a low closing volume.

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