Performance characteristics of the new Eurosets magnetically suspended centrifugal pump

Objective: The aim was to evaluate the performance of a newly developed magnetically suspended centrifugal pump head intended for use as a ventricular assistance device with a newly developed extracorporeal membrane oxygenator setup. Methods: In an experimental setup, an extracorporeal membrane oxygenator circuit was established in three calves with a mean weight of 68.2 ± 2.0 kg. A magnetically levitated centrifugal pump was tested, along with a newly designed extracorporeal membrane oxygenator console, at three different flow ranges: (a) 0.0 to 5.2 L/min, (b) 0.0 to 7.1 L/min, and (c) 0.0 to 6.0 L/min. For each setup, the animals were supported by a circuit for 6 h. Blood samples were collected just before caridiopulmonary bypass (CPB) after 10 min on bypass and after 1, 2, 5, and 6 h of perfusion for hemolysis determination and biochemical tests. Values were recorded for blood pressure, mean flow, and pump rotational speed. Analysis of variance was used for repeated measurements. Results: Mean pump flows achieved during the three 6 h pump runs for the three pump heads studied were as follows: (a) flow range 0.0 to 5.2 L/min, 3.6 ± 1.5 L/min, (b) flow range 0.0 to 7.1 L/min, 4.9 ± 1.3 L/min, and (c) flow range 0.0 to 6.0 L/min, 3.8 ± 1.5 L/min. Blood trauma, evaluated by plasma hemoglobin and lactate dehydrogenase levels, did not help in detecting any significant hemolysis. Thrombocytes and white blood cell count profiles showed no significant differences between the groups at the end of the 6 h perfusion. At the end of testing, no clot deposition was found in the oxygenator, and there was no evidence of peripheral emboli. Conclusion: The results suggest that the newly developed magnetically suspended centrifugal pump head provides satisfactory hydrodynamic performance in an acute perfusion scenario without increasing hemolysis.

In Vivo Testing of a Magnetically Suspended Centrifugal Pump Designed for Long-Term Use

The life of currently-available centrifugal pumps is limited to no more than three days. As a magnetically suspended centrifugal pump (MSCP) contains no shaft or seal, it could be expected to have a longer life expectancy. The MSCP was evaluated in a chronic animal model using eight adult sheep. Left ventricular assist with the MSCP was instituted between the left atrium and the descending aorta. The flow rates ranged from 2.5 to 6.0 L/min. The duration of the experiments ranged from 14 to 60 days. No mechanical failure occurred. The plasma free hemoglobin levels remained within an acceptable range (3-19 mg/dL). No reduction in the counts of red blood cells or platelets was observed. Thrombus formation within the MSCP was recognized in one pump. The main reason for termination was thromboembolism derived from the circuits. Three types of regulation methods (constant rotational speed, constant motor current, and controlled motor current) were also investigated. Regulation by a constant motor current mode altered the pressure-flow (P-Q) characteristics, and thereby, a steadier pump flow was obtained compared with regulation in the constant rotational speed mode. Moreover, the controlled motor current mode can change the P-Q relationship. These results demonstrate that the MSCP is a promising device for long-term use.