A COMPLETELY MAGNETICALLY SUSPENDED AXIAL-FLOW BLOOD PUMP

Abstract

The challenge in the design of blood pumps is to combine CFD and experimental methods in order to minimize development time and maximize the quality of pumps. Our experience shows that only a step-by-step combination of these methods and repetitions of design stages can lead to shorter development times, an optimization of flow patterns with a minimization of hemolysis and platelet activation in the pump. The pump was studied both at the normal design ratings of 5 l/min against a pressure of 100 mmHg and at other operating points. The fluid velocity and pressure distribution, as well as shear stress-related blood damage values were calculated on the basis of theoretical models. The numerical results were evaluated by a comparison with selected experimental trials (LDA, PIV and in-vitro hemolysis tests). We were able, for example, to reduce hemolysis in the pump by a factor of 2.5 by precise optimization of the impeller while retaining all other pump components. The final results were validated in animal experiments with calves, where no increase of plasma-free hemoglobin and other parameters of hemolysis was shown. In clinical trials with 14 patients in 5 different centers, no signs of significant hemolysis were detected, and in a detailed examination of the subsequently disassembled pump, explanted after 178 days of operation in the first patient, no aggregations were found, in fact, the pump was proven to be totally clean.