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Mechanically non-contact axial flow blood pump

Mitamura Y., Kido K., Yano T., Sakota D., Yozu R., Okamoto E., Murabayashi S., Nishimura I.

Biocybernetics and Biomedical Engineering

2007

Vol. 27, no. 1-2

139-146

To overcome the drive shaft seal and bearing problem of the rotary blood pump, a hydro-dynamic bearing, a magnetic fluid seal and a brushless DC motor were employed in an axial flow pump. This enabled contact free rotation of the impeller without material wear. The axial flow pump consists of a brushless DC motor, an impeller and a guide vane. The motor rotor is directly connected to the impeller by a motor shaft. A hydrodynamic bearing is installed on the motor shaft. The motor and the hydrodynamic bearing are housed in a cylindrical casing and are waterproofed by a magnetic fluid seal. Impeller shaft displacement was measured using laser sensor. The axial and radial displacements of the shaft were less than a few micrometers for up to 8500 rpm. The shaft did not touch the housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mmHg. The left ventricular bypass experiment was performed in vitro. With an increase of the motor speed, the bypass flow increased, and at 7000 rpm a total bypass was obtained. The hydrodynamic bearing worked normally under variable load conditions. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal and a brushless DC motor provides contact free rotation of the impeller without material wear.

Mechanical circulatory support systems at Tokyo Medical and Dental University

Ohuchi K., Hoshi H., Watanabe N., Kido K., Yokoyama Y., Asama J., Shinshi T., Shimokohbe A., Yoshikawa M., Takatani M.

Biocybernetics and Biomedical Engineering

2007

Vol. 27, no. 1-2

161-167

This paper describes mechanical circulatory support devices (MCSD) which are under development at Tokyo Medical and Dental University in collaboration with Tokyo Institute of Technology. They include para-corporeal magnetic levitated (Mag-lev) centrifugal blood pump, implantable Mag-lev centrifugal blood pump, extra-corporeal pediatric centrifugal blood pump, and implantable pulsatile ventricular assist device (VAD) and totally replacement artificial heart system.

Current status of the intra-cardiac axial flow pump

Mitamura Y., Yano T., Kido K., Sakota D., Takahashi N., Mori Y., Murabayashi S., Nishimura I., Sekine K.

Biocybernetics and Biomedical Engineering

2006

Vol. 26, no. 1

39-44

Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo-pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo-pump consists of an impeller and a motor. The motor is waterproofed with a magnetic fluid seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa at 7,500 rpm. The normalized index of hemolysis (NIH) was 2.6 times the Bio-Pump. The pump was implanted in three goats between the left ventricle and the aorta. The pump bypassed about 85% of cardiac output. The results showed that the Valvo-pump could maintain systemic circulation with an acceptable level of hemolysis.