Biomedical Engineering Reference
In-Depth Information
FIGURE 8-42
The MiTi
Heart
design. (a) Cross
section through the
integrated motor and
pump. (b) Model of
the pump assembly.
(c) Photo of the
pump. (Courtesy of
MiTi
Heart
Corporation,
reproduced with
permission.)
FIGURE 8-43
Measured
performance of the
latest MiTiHeart
LVAD design
[Adapted from
(MiTi
Heart
2006).]
However, a subsequent reduction in the size of the device has altered these characteristics
somewhat, with the nominal operating point of 5 L/min and 100 mmHg occurring at 4000
rpm, as shown in Figure 8-43.
Another unique feature of the MiTi
Heart
design configuration is the very simple and
direct flow path for both main and washing blood flows. The noncontact nature of the
magnetic bearing allows for fully washed flow paths to avoid stagnation points that might
promote thrombi formation. The design is sufficiently flexible to avoid stagnation points
while at the same time maintaining large enough clearances throughout the flow path to also
eliminate regions of high shear stress. The low shear associated with the relatively large
gaps between the rotating surfaces and lower speeds (4,000 rpm compared with 10,000 rpm
