A SYSTEMATIC METHOD FOR DESIGN AND EVALUATION OF A CARDIAC PUMPING CHAMBER

摘要

Regions of stagnant or recirculating flows near walls within artificial ventricles can cause calcification and thrombogenesis (Harasaki et al., 1985). Similarly, large shear stresses in the fluid domain can lead to blood cell damage, activation of the clotting cascade and thrombosis (Sutera, 1977). Several investigators have performed experiments in LVAD, BVAS and TAH devices to measure these flow characteristics using polystyrene tracer techniques, pulsed Doppler ultrasound velocimetry and Laser Doppler anemometry (Araki, et al., Baldwin et al, 1990). However, each of these methods requires a geometrically accurate model for testing. Device design changes necessitate new flow studies which must await prototype fabrication for complete evaluation of the new internal fluid dynamics. CFD is a practical tool for evaluating flow characteristics within a device under investigation. Using a finite element "rubber mesh" template, the spectral element solver of a powerful computational fluid dynamics (CFD) program and computer simulation-surrogate techniques for design optimization, we have developed an approach to mechanical heart assist design and evaluation. This method allows us to efficiently find the optima in a large design space based on specified cost functions. Our initial application of this approach is to the redesign of a generalized single-chamber mechanical ventricle with fixed stroke volume and ejection time. The effect of changing one descriptor of chamber geometry will be shown with two examples.