IN THE PIPELINE: Pacemaker Could Be Key To Getting Zzz's
By DANIEL ROSENBERG
Of DOW JONES NEWSWIRES
CHICAGO -- People with a common sleep disorder might soon get relief from a
surprising source: the cardiac pacemaker.
Sleep apnea is a condition characterized by frequent episodes in which a
patient stops breathing or breathes less efficiently during sleep. In the
worst cases, sufferers may stop breathing as frequently as 100 times an
hour, often for a minute or longer. Signs of sleep apnea include loud
snoring and gasping for breath.
In an article published earlier this year in the New England Journal of
Medicine, Dr. Stephane Garrigue, a French physician, reported that 15 heart
patients he studied had fewer episodes of sleep apnea when physicians turned
up their cardiac pacemakers during the night.
Scientists at St. Jude Medical Inc. (STJ) were intrigued enough by the
French study to start their own, which is just getting underway in both the
U.S. and Europe and is called Breathe. While the study involves people who
wear pacemakers for their preexisting heart conditions, St. Jude hopes that
someday, if the study meets its goals, sleep apnea patients without heart
problems may also be prescribed a pacemaker.
Pacemakers are battery-powered minicomputers that monitor the heart. If the
heart beats too slowly, a pacemaker sends an electrical pulse down a wire,
forcing it to beat. A pacemaker, typically one to two inches wide and
weighing one to three ounces, is implanted just under the skin in the upper
section of the chest.
"In patients with sleep apnea syndrome, atrial overdrive pacing (with the
pacer causing the heart to beat 15 beats a minute faster than normal)
significantly reduces the number of episodes of central or obstructive sleep
apnea without reducing the total sleep time," Garrigue and his colleagues
wrote. His study reduced sleep apnea by 60%.
About 12 million Americans, including 30% of all pacemaker patients, suffer
from the condition, which can lead to excessive daytime sleepiness,
work-related accidents, auto accidents and heart conditions such as
hypertension and arrhythmias, or irregular heartbeats. A common treatment
for sleep apnea is a device worn during the night that pumps air through a
tube into a mask worn over the nose. Many patients find the device
uncomfortable, and some fail to comply. Drug therapy has proved ineffective.
Two of St. Jude's competitors - Medtronic Inc. (MDT) and Guidant Corp.
(GDT) - are also studying the use of pacemakers in sleep apnea patients. The
idea that an existing device might hold some answers for their patients
excites many doctors.
"If it pays off and is confirmed, it's an extremely exciting area," said Dr.
David Rapoport, associate professor of medicine at New York University
Medical Center and medical director of the NYU Sleep Disorder Center, who is
one of the doctors participating in the Breathe trial. "It's quite
striking."
That doesn't mean the next time your spouse complains about your snoring you
can go to the cardiologist to be fitted for a pacemaker, Rapoport and other
doctors cautioned. A lot of research lies ahead, and in the final analysis,
this therapy may be suitable for only a small portion of sleep apnea
patients. Doctors are still trying to figure out exactly what makes the
therapy seem to work and which patients might benefit the most.
The Breathe study is just starting to accumulate patients, with hopes for a
total of 120. The study seeks to determine whether turning up someone's
pacemaker to treat sleep apnea is safe and effective.
Eric Falkenberg, senior vice president of global research and emerging
indications at the St. Paul, Minn.-based St. Jude, thinks there's nothing
inherently dangerous about turning up a pacemaker to pump the heart about 10
to 15 beats a minute faster.
"If we were turning it up to 110 or 120 (beats per minute), people would be
concerned," Falkenberg said. "But turning it up to 80 to 90 beats per minute
(from around 60 to 70) is pretty trivial. Just by rolling over in bed, your
heart rate goes to 80 to 90."
Doctors Still Trying To Figure Out Why It Works
There are two forms of sleep apnea - central and obstructive. Central sleep
apnea is a disorder related to the central nervous system, and all heart
failure patients have it. It is far less common than obstructive sleep
apnea, which represents about 85% to 90% of cases, though some patients have
both types. Obstructive sleep apnea is characterized by the collapse in
sleep of an airway that, in most cases, is even narrowed during the daytime.
It makes sense to physicians that pumping the heart faster increases blood
flow and primes the central nervous system to increase a sleeping person's
breathing, helping central apnea patients. But that theory doesn't explain
why pacemaker therapy helps patients with obstructive sleep apnea. One goal
of the Breathe study, which is to be evenly divided between both types of
patients, is to see how a pacemaker helps obstructive sleep apnea sufferers.
Many consider obstructive sleep apnea "a predominantly anatomical problem,"
wrote Dr. Daniel Gottlieb in an editorial in the New England Journal of
Medicine. He said obesity is probably the most important cause of sleep
apnea.
Gottlieb called the French study's results "preliminary" but also
"tantalizing." The study, he said, suggests that the heart may be important
in controlling respiration.
St. Jude's Falkenberg said it's easier to explain why pacemakers might
benefit patients with central apnea, but added that for those with
obstructive apnea, the pacemaker, by speeding up the respiratory system,
might tighten muscles in the throat that can impede breathing.
In the Breathe study, doctors will examine patients over a period of one
month. The primary goal is to see if turning up the pacemaker slightly in
some patients means fewer incidents of troubled breathing during sleep.
If the study bears out, St. Jude might one day seek to market its pacemakers
with a premium feature that can speed up the device at night to prevent
sleep apnea.
"It will increase our market share," Falkenberg said. "If a patient is
coming in and their spouse complains that the patient is restless at night,
it's a feature that does no harm. We want to make our devices men for all
seasons."
St. Jude now has about a 27% share of the U.S. pacemaker market. Guidant and
Medtronic are its biggest competitors. Last year, St. Jude's pacemaker sales
totaled $687 million and the company forecasts 2002 pacemaker sales to rise
between 9% and 11% from that figure.
Guidant and Medtronic won't let St. Jude have a monopoly in the sleep
market, should a market develop. Milton Morris, Ph.D, director of applied
research at Guidant's Cardiac Rhythm Management division, called recent
findings on the use of pacemakers for sleep apnea "really interesting," and
said the company has spent several years "actively conducting research" into
how heart devices might be used to treat sleep disorders. He declined to
discuss specific studies the company is conducting.
Marshall Stanton, medical director and vice president of Medtronic's Cardiac
Rhythm Management division, called sleep apnea "an important area," and said
the company has been researching it for at least two years.
About 250,000 new patients get fitted each year with a pacemaker in the
U.S., and St. Jude believes 30% of those patients might be eligible for a
sleep apnea device. That would mean 75,000 a year. In addition, around one
million Americans now wear pacemakers. If 30% of these patients get the new
feature, that's potentially another big market.
Assuming the Breathe trial meets its goals, St. Jude hopes to begin a study
in which sleep apnea patients without pacemakers could be implanted with the
devices to see how they do. Though to the unschooled it sounds like a pricey
and invasive solution for people without a heart problem, pacemaker
implantation is actually a common and relatively painless procedure and the
devices aren't difficult to wear. Sometimes implantation is done at an
outpatient clinic.
Dr. Safwan Badr, president of the American Sleep Apnea Association and
professor of medicine at Wayne State University in Detroit, praised St. Jude
for its effort.
"It is thinking out of the box," Badr said.
He thinks eventually this type of therapy may represent a niche market, but
he's pretty sure it will never be the most common treatment for sleep apnea.
"My hunch is, yes, there's something," Badr said. "I don't think it will be
used for every sleep apnea patient. It's novel, it's new and it's nowhere
near ready for primetime."
-By Daniel Rosenberg, Dow Jones Newswires; 312-750-4118;
daniel.rosenberg@dowjones.com
Updated December 3, 2002 11:00 a.m. EST |
