Evaluation of four blood pump geometries: fluorescent particle flow visualisation technique

Artificial blood pumps play an increasingly important role in the treatment of end-stage cardiac failure. The fluid dynamics of blood flow through such devices crucially affects their clinical effectiveness. Specifically, if the flow of blood stagnates or slowly re-circulates thrombus formation can occur and the avoidance of such flow features is a primary consideration in the design of pumps. The present study concerns the development of a fluorescent particle visualisation technique and its application to investigate the flow environments in four prototype blood pump designs. The procedure involves recording video images of eight illuminated cross sections through the pumping chambers as the pumps operate in a mock circulatory loop using a test fluid seeded with fluorescent particles. The technique enabled a semi-quantitative characterisation of the entire flow field, throughout the pumping cycle, to be performed for each pump design. Flow features were then related to design properties of the individual pumps and recommendations made for design optimisation.