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ASAIO CARDIAC ABSTRACT

MEASUREMENTS IN A BIO-CENTRIFUGAL VENTRICULAR ASSIST DEVICE MODEL

Ong, K S; Chua, L P; Yu, S CM; Zhou, T M

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Animal trials of a magnetically suspended blood pump showed that high hemolysis and thrombus formations were prevalent in the clearance gaps between the impeller shroud and pump casing surfaces. One of the major causes was the design of the pump. To optimize the design, the flow field in the clearance gap for the existing design has been studied. Blood analog was used as the fluid medium. It has the similar viscosity and density as blood. The tangential and radial velocity was measured separately by LDA. The measurements were done at three critical inlet flow conditions, which were at the flow coefficient, F = 0.04, 0.078 and 0. The vector plot of the resultant velocity showed that there was no vortex in the gap. The double volute of the pump has created a washout mechanism at the gap, especially at the splitter plate. The washout mechanism could flush the blood away from the gap. These have suggested that hemolysis and thrombus formations are minimal and hence the pump is able to function nominally efficient as compared to other centrifugal pumps. The results obtained by the LDA and analogue blood were comparable to the study that have been done earlier using hot wire and air as hid medium. The magnitude of the fluid velocity in the gap was relatively lower than those of air. However, the washout mechanism was found to he stronger and more obvious in this more viscous fluid, blood analogue. The detail will he discussed in the full paper.

Copyright © 2004 by the American Society for Artificial Internal Organs