Morphological changes of the pivot bearings in the Gyro Pump C1E3 after clinical use

The Gyro Pump C1E3 incorporates a double-pivot bearing system as a completely sealless centrifugal pump. The male pivot is made of alumina ceramic, and the female is made of polyethylene. Therefore, the durability of this pump depends upon morphological changes of the female polyethylene pivots, which we examined after clinical usage in the present study. We examined 30 pumps, which were used for cardiopulmonary bypass (CPB), in terms of weight, depth, and surface roughness of the female polyethylene pivots. To determine changes caused by clinical use, we also examined 10 pumps of the same lot numbers with the pumps clinically used and stocked in the factory. There were no significant changes in weight of top and bottom pivots. Also, there was no significant difference in depth and surface roughness of the top pivots. However, there was a significant increase in depth and a decrease in surface roughness of the bottom pivots from clinical use. The results revealed that the bottom pivot, rather than the top pivot, is subject to mechanical deformation by clinical use of the Gyro Pump for CPB. Since morphological changes of the bottom pivot may result from spinning of the impeller at the bottom contact phase, the magnetic coupling distance may need to be increased to obtain more stable spinning of the impeller in a routine CPB.