Page 554 - Handbook of Biomechatronics

Artificial Hearts 547

Fig. 21 Measured performance of the latest MiTiHeart LVAD design. (Based on MiTiHeart
Corporation.)

Fig. 22 Schematic diagram showing the VentrAssist pump. (Based on Gosline, A., 2004.
Simpler pump boosts failing hearts. New Sci. 28 July.)

weight substantially compared to the MiTiHeart. It weighed only 298g and
was <60mm in diameter, making it suitable for both children and adults.
The device had only one moving part, a hydrodynamically suspended
impeller made from a titanium alloy and covered with a diamond-like coat-
ing. Because of the large impeller size, it rotated relatively slowly and the
impeller had no shaft seals or bearings ensuring clean flow lines with no stag-
nant zones.
Rotating magnetic fields generated by the six copper coils in the base and
walls of the unit interact with the permanent magnets mounted within the
rotor and cause it to spin rapidly. Hydrodynamic forces, which result from
the small clearances between the outside surfaces of the impeller and the
pump walls, support it. These small clearances range from 50 to 230μm
(Chung et al., 2004). Blood enters the center of the pump and is spun up