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Implantable Device May Monitor Organs
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Alpha-Omega
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Jul 30, 2003 16:49 PDT
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Implantable Device May Monitor Organs
December 23, 2002 05:59 AM EST
ARDEN HILLS, Minn. - Data recorders in airplanes, the so-called black
boxes, describe what went wrong after a disaster. Now, medical devices
are emerging to act like a black box in the human body, except they're
being used to prevent disaster.
Though still in an early stage, a market is growing for implantable
monitors, tiny devices that track the function of a person's organs.
Five years ago, Medtronic Inc. released its first implantable monitor
for people with mysterious fainting spells. Though a niche product for
the giant maker of pacemakers and defibrillators, it was a breakthrough,
giving doctors far more data about effects on a fainting person's heart.
Two product generations later, Medtronic has sold more than 25,000 of
the 2-inch-long monitors, which weigh just a few grams. They're placed
in a person's pectoral muscle, sometimes for just a few days, and track
heart activity in a 42-minute loop.
When a person recovers from a fainting incident, he or she stops the
monitor. A doctor or nurse can then retrieve the data with a special
radio receiver, and restart the loop.
Other implants are being readied to monitor blood pressure and heart
rate _ even inside the heart itself.
The Medtronic monitor, known as Reveal, has become useful beyond
fainting spells.
Robert Willoughby, 71, who had one of the monitors implanted in his
chest almost two years ago, suffers from myotonic dystrophy, a
degenerative muscle condition often marked by an irregular heartbeat.
Willoughby, of Lapel, Ind., tried wearing an external electrocardiogram
monitor to watch for unusual heart events, but the bulky device was a
nuisance.
His implanted monitor, by contrast, is constantly alert to capture and
store up to 13 unusual events that occur during its loop. Its
information is downloaded in quarterly visits to his doctor.
A year after receiving it, Willoughby's device detected atrial
fibrillation, an irregular heartbeat that can increase the risk of
stroke. His doctor prescribed blood thinners.
"I don't mind dying suddenly from a heart attack," the former General
Motors tool-and-die worker said. "But I don't relish the idea of
spending days in an infirm condition in a nursing home."
Immediately after Medtronic's device hit the market, the quality of
diagnosis for people with infrequent fainting spells shot up.
"A lot of the pull for the device came from patients, people who were
frustrated, weren't able to drive, in disarray because fainting messed
up their lives," said Brian Lee, the device's co-inventor.
The Reveal is just the start for implanted monitors.
The advance of wireless technology and the Internet allowed makers of
other implants, such as pacemakers and defibrillators, to add monitoring
features.
Medtronic and rival Biotronik Inc. in the past year began selling such
products.
With the Baby Boomer generation hitting old age in the next two decades,
doctors hope implantable monitors will help them treat patients for less
cost with fewer hospital visits.
Developers envision implantables that track pressure in the brains of
spina bifida patients who require fluid-draining shunts. For paraplegics
who have lost sensitivity in their bladder, an implant could signal when
it's time to urinate.
"Theoretically speaking, you can record many other things, such as blood
pressure, blood sugar," says George Klein, a Canadian doctor who asked
Medtronic to help develop the Reveal. "You've got a little device that's
monitoring all kinds of biochemical and physiological information that
can be transmitted to a medical center or to other devices in the body."
Data Sciences International Inc., a small company near Medtronic's
headquarters in this Minneapolis suburb, will start clinical trials next
year of monitors that can track blood pressure inside the heart itself.
The company, which produced implantable monitors in lab animals, is
racing with Medtronic to produce devices aimed at heart failure
patients.
Data Sciences also made progress with pressure-sensing and packaging
technologies. Traditionally, implanted devices like pacemakers were
packaged in titanium. Data Sciences will rely on new ceramic material.
Its first product will have a home base station that reads the radio
signal sent from the implanted blood pressure monitor. The device plugs
into a phone jack and transmits data to the patient's doctor.
Medtronic's competing product, called Chronicle, works in a similar
fashion and is already in clinical trials.
To many doctors, implanted devices represented a last resort. Few
believed they should be used for diagnosis, preferring to implant only
devices that correct problems, as pacemakers and defibrillators do.
But the success of Medtronic's Reveal forced doctors to re-evaluate.
"The tools are safer, smaller, better, all these features that make them
not as intrusive," said Susan Foote, a University of Minnesota professor
who studies medical technology policy.
AP News Editor Doug Glass in Minneapolis contributed to this story.
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Copyright © 2002 Associated Press. All rights reserved.
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