NEXT- GEN PACEMAKERS MAY BE POWERED BY UNLIKELY SOURCE
The
implantable pacemaker, a medical marvel that has extended millions of lives
since its invention nearly 60 years ago, is getting a 21st century makeover.
First came a wireless version; these pacemakers, which are AAA battery-sized
and placed inside the heart via a catheter through the leg, are being tested in
humans in the United States, Canada and Australia.
Now,
researchers are developing technology to make these devices battery-free. The
advancement is based upon a piezoelectric system that converts vibrational
energy -- created inside the chest by each heartbeat -- into electricity to
power the pacemaker.
"Essentially,
we're creating technology that will allow pacemakers to be powered by the very
heart that they are regulating," says M. Amin Karami, PhD, assistant
professor of mechanical engineering at the University at Buffalo School of
Engineering and Applied Sciences, who is leading the research. The technology
may eliminate the medical risks, costs and inconvenience of having a battery
replacement every five to 12 years for millions of people worldwide. From the
beginning The development of pacemakers dates back nearly a century. At the
beginning, most efforts focused on devices that patients would carry outside
their body. Surgeons first successfully implanted a pacemaker in a human in
1960 in Buffalo, New York. The device, invented by UB alumnus Wilson
Greatbatch, enabled the patient to survive another 18 months. (Note: A patient
in Sweden received an implantable pacemaker in 1958, but the device failed
after three hours.)
While there
have been advancements since 1960 -- the devices are smaller, the batteries
last longer, there are even "smart" pacemakers that are linked to
computers -- the basic design from Greatbatch is the same. About the size of a
pocket watch, pacemakers are implanted under the skin through an incision in
the chest. Wires, also called leads, connect the device to the heart and
deliver electrical signals that regulate the heart's activity.
The new
wireless option does not require leads because it rests inside the heart. This
removes a potential point of failure, but the device still relies on a battery
that must be replaced as often as the batteries that conventional pacemakers
use. A state of constant motion
The idea of
heart-powered pacemakers came to Karami after doing PhD work on piezoelectric
applications for unmanned aerial vehicles and bridges. He wanted to apply that
knowledge to the human body. The heart was an obvious choice because of its
relative strength and constant motion. "To see the heart in motion -- even
an animation -- is to be awestruck," says Karami. "It moves
significantly. In turn, that movement creates energy that we're just now
figuring out how to harvest." Karami is not the first person with the
idea. He found designs from the 1960s attempting the same. But they lacked the
scientific knowledge and modern technology available today.
He initially
designed a flat piezoelectric structure for a conventional pacemaker. A
prototype generated enough power to keep the pacemaker running at a range of 7
to 700 beats per minute. With the development of wireless pacemakers, however,
he has revamped the design to accommodate the smaller, tube-shaped device.
Karami, who is already talking to device-makers, is building the new prototype
and expects to have animal tests done within two years. From there, it should
be ready for human trials and, eventually, approval from the U.S. Food and Drug
Administration.
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