Model Studies at Mechanical Aortic Heart Valve Prostheses—Part I: Steady-State Flow Fields and Pressure Loss Coefficients

1988 ◽  
Vol 110 (4) ◽  
pp. 334-343 ◽  
Author(s):  
Martin Knoch ◽  
Helmut Reul ◽  
Ralf Kro¨ger ◽  
Gu¨nter Rau
Keyword(s):  
Heart Valve ◽  
Vortex Formation ◽  
Flow Fields ◽  
Turbulent Shear ◽  
Human Aorta ◽  
Shear Stresses ◽  
Scaled Model ◽  
Jude Medical ◽  
Heart Valve Prostheses ◽  
Valve Prostheses

In a 3:1 scaled model of the human aorta models of the Omniscience, Bjo¨rk-Shiley Convexo-Concave, Bjo¨rk-Shiley Monostrut, Medtronic-Hall, Duromedics (Hemex) and the Saint Jude Medical heart valve prostheses are studied in steady flow representing the systolic peak flow phase. Detailed flow visualization experiments show flow separations at all inner ring surfaces as well as at most of the occluders. The resulting stagnation areas increase the risk of thrombus accumulation. Flow separations also stimulate vortex formation and turbulent mixing at the downstream jet boundaries and thus may intensify blood damage by turbulent shear stresses. The different influences of struts and occluder guides on the flow around the occluders are discussed. The effects of the individual valve components on the flow fields are analyzed and correlated with the resulting pressure losses.

19 mm Sized Bileaflet Valve Prostheses’ flow Field Investigated by Bidimensional Laser Doppler Anemometry (part II: Maximum Turbulent Shear Stresses)

1997 ◽  
Vol 20 (11) ◽  
pp. 629-636 ◽  
Author(s):  
V. Barbaro ◽  
M. Grigioni ◽  
C. Daniele ◽  
G. D'avenio ◽  
G. Boccanera
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Turbulent Shear ◽  
Shear Stresses ◽  
Draft Guidance ◽  
Blood Constituents ◽  
Jude Medical ◽  
Valve Prostheses ◽  
Bileaflet Valve

The investigation of the flow field generated by cardiac valve prostheses is a necessary task to gain knowledge on the possible relationship between turbulence-derived stresses and the hemolytic and thrombogenic complications in patients after valve replacement. The study of turbulence flows downstream of cardiac prostheses, in literature, especially concerns large-sized prostheses with a variable flow regime from very low up to 6 L/min. The Food and Drug Administration draft guidance requires the study of the minimum prosthetic size at a high cardiac output to reach the maximum Reynolds number conditions. Within the framework of a national research project regarding the characterization of cardiovascular endoprostheses, an in-depth study of turbulence generated downstream of bileaflet cardiac valves is currently under way at the Laboratory of Biomedical Engineering of the Istituto Superiore di Sanità. Four models of 19 mm bileaflet valve prostheses were used: St Jude Medical HP, Edwards Tekna, Sorin Bicarbon, and CarboMedics. The prostheses were selected for the nominal Tissue Annulus Diameter as reported by manufacturers without any assessment of valve sizing method, and were mounted in aortic position. The aortic geometry was scaled for 19 mm prostheses using angiographic data. The turbulence-derived shear stresses were investigated very close to the valve (0.35 D0), using a bidimensional Laser Doppler anemometry system and applying the Principal Stress Analysis. Results concern typical turbulence quantities during a 50 ms window at peak flow in the systolic phase. Conclusions are drawn regarding the turbulence associated to valve design features, as well as the possible damage to blood constituents.

Pressure Recovery in Bileaflet Heart Valve Prostheses

Circulation ◽  
1995 ◽  
Vol 92 (12) ◽  
pp. 3464-3472 ◽  
Author(s):  
Pieter M. Vandervoort ◽  
Neil L. Greenberg ◽  
Min Pu ◽  
Kimerly A. Powell ◽  
Delos M. Cosgrove ◽  
...  
Keyword(s):  
Heart Valve ◽  
Pressure Recovery ◽  
Heart Valve Prostheses ◽  
Valve Prostheses

Pathogenesis of fungal infection on heart valve prostheses

1975 ◽  
Vol 6 (6) ◽  
pp. 711-715 ◽  
Author(s):  
Stanley J. Robboy ◽  
John Kaiser
Keyword(s):  
Fungal Infection ◽  
Heart Valve ◽  
Heart Valve Prostheses ◽  
Valve Prostheses
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