By Jeff Karoub
Small Times Staff Writer
July 2, 2001 — Small technology is at the heart of an advanced pacemaker implanted in Vice President Dick Cheney’s chest on Saturday.
The Medtronic GEM III DR, a pacemaker and implantable cardioverter-defibrillator (ICD), now constantly records Cheney’s heart activity and can speed up or slow down an irregular rhythm. And it’s all in a package the size of a small pager.
 |
| The Medtronic GEM III DR can speed up or slow down an irregular heart rhythm. |
A MEMS accelerometer, which monitors the heart’s activity level, works alongside a microprocessor to detect the level and deliver more electricity to keep the heart in rhythm. In the case of the ICD, the device delivers a high-energy electrical shock to bring the ventricles back to normal rhythm.
“It’s an emergency room in your chest,” said Bob Hanvik, a spokesman for Medtronic Inc., the Minneapolis-based market leader in pacemaker and ICD sales. “It actually recognizes when a potentially life-threatening arrhythmia might occur, and gives you a shock before it can escalate to life-threatening.
“That’s why Cheney described it as an ‘insurance policy.’ … Ultimately, the hope is it would never have to deliver therapy, but it’s nice to know it’s there.”
He said MEMS technology, which has been used in ICDs for about a decade, not only makes the devices more efficient, but much smaller.
Cheney, who has a history of heart problems, had the device implanted Saturday at George Washington University Medical Center. He needed the ICD, doctors said, because tests performed two weeks ago showed four episodes of a very fast and potentially fatal heart rhythm.
Cheney’s device, placed just under the skin of the left shoulder, weighs about 80 grams, and is two inches square and about a half-inch thick. The first internal defibrillators were bigger than a cigarette pack and had to be implanted near the stomach because of their size.
“Several years ago, (implanting an ICD) was similar to an open-heart procedure,” Hanvik said. “Now … a small slit is made into the chest, and it’s oftentimes done on an outpatient basis.”
MEMS also allow the ICDs to adjust to a heart’s activity level. Previous devices used to offer a constant level of therapy, even if a patient’s heart rhythm varied widely, he said.
The devices do this with the help of two fine titanium and silicone rubber wires that are threaded from the device into veins that lead to the heart. One is used for pacing and the other acts as the defibrillator.
Dianna Bash, nurse manager of the electrophysiology laboratory at the Cleveland Clinic Foundation, has been involved with ICDs since 1981, when she took care of the clinic’s first patient to have one implanted.
“We used to call it a ‘shock box,'” she said. “They would shock at a predetermined rate. But over the years, they have become very sophisticated. The device got very smart.”
And, with advances in small tech, they are getting smarter still.
The application that holds the most promise, Bash said, involves placing a third lead into the left ventricle in patients with low heart function. The biventricular pacing, as it’s known, could reduce, or one day even eliminate, the need for heart transplants. Several companies, including Medtronic, are running trials.
Pacemaker and defibrillator manufacturers also are developing Internet-enabled devices.
Medtronic currently is running a clinical trial for a device called the Chronicle, which monitors heart activity and transmits information to secure Internet sites. The company expects to carry the technology over into its ICDs as early as this year, pending completion of the study and approval from the U.S. Food and Drug Administration.
Hanvik would not disclose Medtronic’s sales figures for the GEM III DR, but he said the company sells more than half of the pacemakers and ICDs implanted in about 50,000 U.S. residents a year. It costs between $20,000 and $25,000 to have the GEM III installed, and that includes everything related to the procedure, he said.
He hopes that having one of his company’s devices implanted in the vice president boosts sales, but he said it’s more important that the publicity increases awareness of ICDs and pacemakers. Now, only 15 percent of people flagged as candidates for an ICD in the United States actually have one implanted. That leaves the other 85 percent at risk of sudden cardiac death, Hanvik said. Heart attacks kill 225,000 Americans a year.
“Having the vice president understand the role of a device like this … (makes) it more acceptable,” he said. “It demonstrates people can go on living normal active lives, and makes people more comfortable with the therapy.”
Bash said she has seen ICDs evolve from providing a last resort to offering a new lease on life.
“It’s not just for 70-year-olds – they can be for 18-year-old athletes,” she said. “They help normal, healthy people who just happen to have a rhythm disturbance.
“You used to really have to be in the bottom of the pit to get one of these. Now, you can drive, return to work, and go about your daily business.”