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Abstracts: ASAIO Bioengineering/tissue Engineering Abstracts

PREDICTION AND MEASUREMENT OF MECHANICAL HEMOLYSIS IN AN IMPLANTABLE CENTRIFUGAL BLOOD PUMP

Arora, Dhruv1; Hussain, Fazle2; Behr, Marek1,3; Pasquali, Matteo4; Yuri, Koichi5; Motomura, Tadashi5; Nose’, Yukihiko5

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The GYRO implantable Bi-Ventricular Assist Device (BVAD), under development at Baylor College of Medicine, TX, has been studied. The hemolysis in the pump is measured at three physiological operating conditions, namely horizontal top-contact position at 1600, 2000 and 2350 RPM. The measured NIH (Normalized Index of Hemolysis) is 0.007, 0.007 and 0.02, respectively. The three-dimensional, time dependent flow in the pump is modeled by the Navier-Stokes equations, and solved by the Deformable-Spatial-Domain/Stabilized-Space-Time finite element method. The complex flow features are documented and analyzed. Hemolysis is predicted along the pathlines using two hemolysis models: the traditional stress-based model and a recent model based on tracking the strain (tensor) experienced by the Red Blood Cells (RBCs) (strain-based model). The strain-based model accounts for documented physical properties of the RBCs, including their relaxation time (∼200 ms) and flow-induced tank-treading motion of their membrane. The hemolysis predicted by the strain-based model is within the error margins of the experimental values, while the stress-based model predicts higher hemolysis. Moreover, some key features of the pump design are examined by various pathlines. It is found that at all flowrates the average residence time along the calculated pathlines is lower than the expected value based on flowrate and pump volume. This is explained by noting that some portions of the pump are hardly accessible to the bulk flow.

Copyright © 2005 by the American Society for Artificial Internal Organs