Biomedical Engineering Reference
In-Depth Information
•
External battery
: This battery is worn on a Velcro-belt pack around the patient's
waist. Each rechargeable battery offers about 4 to 5 hours of power. During sleep
and while batteries are being recharged, the system can be plugged into an electrical
outlet.
•
Controller
: This small electronic device is implanted in the patient's abdominal
wall. It monitors and controls the pumping speed of the heart.
As can be seen in Figure 8-18, the heart is made from clear epoxy and titanium
so that it can be visually inspected during the implant process to ensure that it is
working correctly and that no air is trapped within the device (Texas Heart Institute,
2008).
The heart pump consists of the following components, as shown in Figure 8-19:
•
Hydraulic pump:
An efficient electric motor spins the impeller inside the cen-
trifugal pump at 10,000 rpm to create the required hydraulic pressure in a silicone
hydraulic fluid.
•
Porting valve:
A separate motor rotates the valve, which opens and closes to let
the hydraulic fluid flow from one side of the artificial heart to the other.
•
Artificial ventricle:
When the fluid moves to the right, it compresses the flexible
membrane on the inner surface of the right artificial ventricle (pump sac), and
blood is pumped to the lungs via a nonreturn valve. When the fluid moves to the
left, a similar sac is compressed, and blood is pumped to the rest of the body via a
separate nonreturn valve.
AbioMed officials have cautioned against overly optimistic results for the first patients
to receive a transplant. While doctors hope for more, the device is designed to only double
life expectancy for patients who had only about 30 days to live prior to the operation. The
most optimistic predictions are that a patient may be able to live up to 6 months with the
AbioCor heart.
FIGURE 8-19
Abiocor (a) Cutaway
view of the internal
workings of the TAH.
(b) Graphic showing
its connection into a
human patient.
(Courtesy of
AbioMed, with
permission.)
