Abstract
Detailed flow investigations of mechanical heart valve protheses are performed in a 3:1 scaled model of the human aorta. Lucite valve models of the Björk-Shiley Convexo-Concave, Björk-Shiley Monostrut, Omniscience, St, Jude Medical and Duromedics prostheses are investigated in this model. The influence of individual valve components on the flow fields and on the pressure losses is analyzed in steady flow. A modified test setup is used in order to visualize the instationary flow fields and occluder dynamics in physiological pulsatile flow. For flow visualization, the model fluid is water and both particle tracer and hydrogen bubble techniques are employed. A distinct increase in spatial and temporal resolution is achieved in the scaled up model satisfying the similarity laws.
Flow separations in all cases are found to create stagnation areas at the valve surfaces and stimulate vortex formation and turbulent mixing at the downstream jet boundaries which may lead to intensified blood damage and thrombus accumulation. All investigated valve models show a similar behavior in the early occluder opening phase whereas the beginning of the closing phase and the closing time interval are strongly dependent on the occluder design.
Future valve designs should eliminate any flow separations at the valve surfaces. This will result in more uniform surface shear stress distribution and minimize pressure loss for a given geometric opening area. Additionally it should allow for a fast closing response in order to reduce backflow and shock load.
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© 1990 Springer-Verlag Berlin Heidelberg
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Knoch, M., Reul, H., Rau, G. (1990). Model Studies at Mechanical Aortic Heart Valve Prostheses in Steady and Physiological Pulsatile Flow. In: Liepsch, D.W. (eds) Biofluid Mechanics. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-52338-0_9
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DOI: https://doi.org/10.1007/978-3-642-52338-0_9
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