Implantable Device May Monitor Organs
Mon Dec 23, 7:37 AM ET Add Health - AP to My Yahoo!


By EVAN RAMSTAD, AP Business Writer

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.

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AP News Editor Doug Glass in Minneapolis contributed to this story.


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