Design and evaluation of a single-pivot supported centrifugal blood pump

In order to develop a centrifugal blood pump that meets the requirements of a long-term, implantable circulatory support device, in this study a sing e-pivot bearing supported centrifugal blood pump was designed to evaluate i ts basic performance. The single-pivot structure consisted of a ceramic bal l male pivot mounted on the bottom surface of the impeller and a polyethyle ne female pivot incorporated in the bottom pump casing. The follower magnet mounted inside the impeller was magnetically coupled to the driver magnet mounted on the shaft of the direct current brushless motor. As the motor ro tated, the impeller rotated supported entirely by a single-pivot bearing sy stem. The static pump performance obtained in the mock circulatory loop rev ealed an acceptable performance as a left ventricular assist device in term s of flow and head pressure. The pump flow of 5 L/min against the head pres sure of 100 mm Hg was obtained at rotational speeds of 2,000 to 2,200 rpm. The maximum pump flow was 9 L/min with 2,200 rpm. The maximum electrical-to -hydraulic power conversion efficiency was around 14% at pump flows of 4 to 5 L/min. The stability of the impeller was demonstrated at the pump rpm hi gher than 1,400 with a single-pivot bearing without an additional support a t its top. The single-pivot supported centrifugal pump can provide adequate flow and pressure as a ventricular assist device, but its mechanical stabi lity and hemolytic as well as thrombotic performances must be tested prior to clinical use.