Development of magnetically suspended centrifugal pump (MSCP) and operation system

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To overcome problems derived from the shaft within conventional centrifugal pump, we have developed a magnetically suspended centrifugal pump (MSCP) , which operates as a bearingless sealless centrifugal pump. The impeller is suspended freely and centrally by magnetic force within the pump. Hemolysis tests were performed in comparison with the Biopump. Index of hemolysis and destruction of platelets were significantly lower in the MSCP.Animal studies were designed to evaluate antithrombogenecity and durability of the MSCP.Short-term animal studies in which several coating methods on the impeller of the pump were investigated showed that silicon coating was best with results of no thrombus on the surface after continuous pumping for 24 hours. Long-term animal studies were performed using 5 sheep weighing 40 - 50 kg. The left heart by pass was established with a withdrawal cannula into the left atrium and a return cannula into the descending aorta. Heparin was given for anticoagulation only at cannulation, and Warfarin was orally administrated subsequently to keep the prothrombin time 1.5 to 2.0 folds. Five sheep survived more than two weeks with 46 days of the longest survival. The pump flow rate obtained during the pumping was 3.0 to 5.0 l/min. The free hemoglobin concentration was less than 20 mg/dl, and other parameters relating biochemistry were within normal ranges. The cause of termination was thrombus formation in the cannula in two, systemic infection in one, gastrointestinal disturbance in one, and thrombus inside the pump in one sheep, that was the longest survival. These results suggest that the MSCP could be durable for at least more than a month, and is promising for application of long-term circulatory assist device, whch is mandatory to rescue patients with the profound heart failure.