An Implantable Seal‐less Centrifugal Pump with Integrated Double‐Disk Motor

Abstract

Thrombus formation and sealing problems at the shaft as well as the compact and efficient design of the driving unit have been major difficulties in the construction of a long-term implantable centrifugal pump. To eliminate the problems of the seal, motor size, and efficiency, two major steps were taken by modifying the Vienna implantable centrifugal pump. First, a special driving unit was developed, in which the permanent magnets of the motor themselves are used for coupling the force into the rotor. Second, the rotor shaft in the pumping chamber was eliminated by adopting a concept recently presented by Ohara. The rotor is supported by 3 pins, which run on a carbon disk, whose concave shape leads to stabilization. The device has the following specifications: size: 65 mm (diameter) by 35 mm (height), 101 cm3; priming volume 30 cm3, 240 g; and a 6-pole brushless double disk DC motor. The required input power of the described prototype is 15 W at 150 mm Hg, 5 L/min (overall eta = 11%), and has an in vitro index of hemolysis (IH) of 0.0046 g/100 L. The test for in vitro thrombus growth exhibited far less thrombus formation in the new design than in designs with axles. In conclusion, the design of a special driving unit and the elimination of the axle led to the construction of a small pump with very low blood traumatization.

Current Status of the Gyro Centrifugal Blood Pump—Development of the Permanently Implantable Centrifugal Blood Pump as a Biventricular Assist Device (NEDO Project)

“…This pump can provide 5 L/min against 120 mm Hg total pressure head at 2000 rpm. The normalized index of hemolysis (NIH) value of this pump was comparable to that of the BP-80 pump (BioMedics, Minneapolis, MN, U.S.A.) (10). The Gyro PI-601 was implanted as a right or left ventricular assist device in the preperitoneal space of five calves (14,15).…”

“…28, No. 10,2004 analysis revealed that a washout flow was created between the bottom shaft and the bottom pivot bearing when the impeller was levitated. In addition, a levitated impeller has less platelet adhesion than when nonlevitated around the bottom pivot area behind the impeller (24).…”

“…28, No. 10,2004 event that the system malfunctions, the system should be simple enough for a patient or family member (25). Therefore, we believe that "a simple pump is best.…”

Development and Initial Testing of a Permanently Implantable Centrifugal Pump

“…The driver motor for the actuator is a brushless DC one with the coils fixed in a plastic mold and mounted on the circumference of the housing. This coil apparatus is placed between 2 rotating disks with permanent magnets that are mounted on 1 central axle (6). The motor is encapsulated in a titanium housing to guarantee hermetic sealing.…”

Development of a Pivot Bearing Supported Sealless Centrifugal Pump for Ventricular Assist

“…Recently, rotary blood pumps have been achieving remarkable progress, as reported by many investigators (12)(13)(14)(15). We think that cost-effective and simple implantable nonpulsatile pumps will be developed in the near future as bridge-to-transplantation devices or as long-term VADs for clinical use,…”