Development of Centrifugal Pumps for Long-Term Circulatory Support

We have been developing centrifugal pumps for long-term use. The basic design of our pump series is a non-seal and no-shaft structure, with a central balancing hole made for continuous blood irrigation around the impeller. The first model, National Cardiovascular Center (NCVC)-0, had an impeller with four rectangular, curved vanes. To reduce the hemolysis rate, we employed six triangular curved vanes for the impeller in the second model, NCVC-1. To achieve further improvement in antithrombogenicity, in the third model, NCVC-2, the central hole was enlarged to enhance the blood-washing action. Six NCVC-0 and four NCVC-1 pumps were evaluated in long-term animal experiments; nine pumps were driven for more than 10 days, 3 were driven for more than 1 month, and one NCVC-1 pump ran for 80 days without anticoagulation. Three NCVC-2 pumps were driven without problems in 1-week experiments without antithrombotic therapy. The hemolysis indices were 0.05 g/1001, 0.01 g/1001, and 0.006 g/1001 in the NCVC-0, NCVC-1 and NCVC-2 pumps, respectively, while the mean value for the Biopump (BP-80; Bionediens, Prairie, MN, USA) was 0.008g/1001. An NCVC-1 pump was implanted inside the chest of a 52-kg goat as a left atrium-to-descending aorta bypass. These results suggest that our centrifugal pump could serve as an adequate circulatory support system for long-term usage.