What Is a Total Artificial Heart?
A total artificial heart (TAH) is a device that
replaces the two lower chambers of the heart. These chambers are called
ventricles (VEN-trih-kuls). You may benefit from a TAH if both of your
ventricles don't work due to end-stage
heart
failure.
Heart failure is a condition in which the heart is
damaged or weakened and can't pump enough blood to meet the body's needs. "End
stage" means the condition has become so severe that all treatments, except
heart
transplant, have failed.
Overview
You may need a TAH for one of two reasons:
- To keep you alive while you wait for a heart
transplant
- If you're not eligible for a heart transplant,
but you have end-stage heart failure in both ventricles
The TAH is attached to your heart's upper
chambersthe atria (AY-tree-uh). Between the TAH and the atria are
mechanical valves that work like the heart's own valves. Valves control the
flow of blood in the heart. (For more information, see the Diseases and
Conditions Index
How
the Heart Works article.)
Currently, there are two types of TAH. They're known
by their brand names: the CardioWest and the AbioCor. The main difference
between these TAHs is that the CardioWest is connected to an outside power
source and the AbioCor isn't.
The CardioWest has tubes that, through holes in the
abdomen, connect from inside the chest to an outside power source.
Normal Heart and CardioWest Total
Artificial Heart
Figure A shows the normal anatomy
and location of the heart. Figure B shows a CardioWest TAH. Tubes exit the body
and connect to a machine that powers and controls how the CardioWest TAH
works.
The AbioCor TAH is completely contained inside the
chest. A battery powers this TAH. The battery is charged through the skin with
a special magnetic charger.
Energy from the external charger reaches the
internal battery through an energy transfer device called transcutaneous energy
transmission, or TET.
An implanted TET device is connected to the
implanted battery. An external TET coil is connected to the external charger.
Also, an implanted controller monitors and controls the pumping speed of the
heart.
Normal Heart and AbioCor Total
Artificial Heart
Figure A shows the normal anatomy
and location of the heart. Figure B shows an AbioCor TAH and the internal
devices that control how it works.
Overview
A TAH usually extends life for months beyond what is
expected with end-stage heart failure. If you're waiting for a heart
transplant, a TAH can keep you alive while you wait for a donor heart. It also
can improve your quality of life. However, a TAH is a very complex device. It's
challenging for surgeons to implant, and it can cause complications.
Currently, TAHs are used only in a small number of
people. Researchers are working to make even better TAHs that will allow people
to live longer and have fewer complications.
September 2008 |