Evaluation of four blood pump geometries: the optical tracer technique

Artificial blood Dump assistance of the failing human heart can allow it to recover. Analysis of blood pump fluid flow is a useful tool for design dev elopment and thrombosis minimization. The aim of this study was to investig ate fluid flow, particularly ventricular clearance rate and stagnation area s, in four different blood pump geometries and to determine the best design . The blood pumps consisted of a polyurethane ventricle, and combinations o f inlet/outlet pipe angles and compression plate shapes. A video camera rec orded the motion of fluid labelled with an optical tracer (Methyl Blue hist ological dye). A novel processing method was developed to produce colour ma ps of tracer concentration, experimentally calibrated. An overall picture o f fluid flow in each pump geometry was generated by considering clearance c urves, tracer concentration maps and inflow jet animations. Overall and loc al mixing coefficients are calculated for each pump. The best geometry feat ured straight inlet/outlet pipes and a domed compression plate. This optical tracer technique has proven convenient, economical, sensitive to low concentrations of tracer and provides instantaneous pictures of trac er distribution in a ventricle.