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Pacemakers Control Sleep Apnea

Ratcheting up beat gives heart patients good night's sleep

WEDNESDAY, Feb. 6, 2002 (HealthDayNews) -- In a surprising and largely inexplicable finding, French scientists say pacemakers appear to correct sleep apnea in some patients.

The discovery, reported in tomorrow's New England Journal of Medicine, probably directly impacts only 10 per cent to 15 percent of people with apnea -- those with abnormal heart function, the researchers say. But if scientists can figure out why pacing helps restore proper nighttime breathing, they might uncover new therapies for other patients as well.

Sleep apnea affects approximately 22 million Americans, with men outnumbering women 2 to 1. Patients with the obstructive form of the disorder have narrowed airways -- chiefly the result of obesity -- that interrupt their breathing many times during the night. A much smaller number of people have so-called central apnea, nocturnal neurological confusion that disrupts proper breathing.

As a result of the disturbances, those with apnea sleep fitfully and are typically tired throughout the day. They fall asleep at their desks and behind the wheel. Not coincidentally, sleep apnea is believed to be a major cause of motor vehicle accidents in the United States. Safety officials estimate that 50 percent of crashes are probably tied to fatigue.

If left untreated, sleep apnea can lead to a wide range of health problems, including impotence, high blood pressure, heart disease, strokes, memory and cognitive problems, and even death.

In an earlier study, Dr. Jacques Clementy and his colleagues at the Hopital Cardiologique du Haut-Lvque in Pessac, France, noticed that patients with rapid heartbeats had fewer breathing problems when their pacemakers were running fast.

In the latest research, Clementy's group performed a similar experiment involving 15 elderly men and women who'd received pacemakers to correct abnormally slow beats, or bradycardia. Every patient also had varying degrees of obstructive or central sleep apnea, causing snoring, fatigue in the morning, and daytime drowsiness.

For three nights, Clementy and his colleagues monitored the patients as they slept, recording their bouts of sleep apnea. During two of those nights, they left the pacemakers unchanged. But during one, they ratcheted up the beating rate by 15 a minute, to an average of 72 per minute.

And the occurrence of sleep apnea dropped markedly. With the pacemakers in overdrive, 13 of 15 patients had at least 50 percent fewer sleep disruptions during the night, yet managed to slumber as long as they normally did. The remaining two had somewhat smaller, but still substantial, reductions in apnea. Patients also had much fewer episodes of hypopnea, or abnormally shallow breathing, when their heart rates were faster.

Surprisingly, the technique helped correct both central and obstructive apnea equally well, even though the latter form of the condition is caused by flesh that blocks the airways.

Clementy says he doesn't know why pacing might improve apnea, but he has a guess. "One hypothesis is that the stimulation plays a role on the muscles in the pharynx [the area in the throat beyond where the nasal cavity and mouth unite] to increase the tone of the muscle and decrease the obstruction," he says. Some experimental evidence suggests that might be a sound explanation, he adds.

The researchers now plan a study to see which apnea patients are most likely to benefit from pacing, and they'd also like to figure out why the technique works.

Dr. Daniel Gottlieb, a Boston University apnea expert and author of an editorial accompanying the journal article, agrees that pacemakers might encourage better muscle tone and thus improve nighttime breathing.

"We know that there are nerves that go to the brain stem from the heart, but we don't know they have an effect on breathing," he says.

If that is indeed the mechanism by which pacing helps control apnea, the devices may be useful for older, non-obese people with the condition who aren't suffering from too much bulk in the throat. "That's a group that could potentially benefit from some therapy aimed at increasing the muscle tone in the upper airway," he says.

What To Do

To find out more about sleep apnea, visit the National Institute of Neurological Disorders and Stroke or the American Sleep Apnea Association.

For more on sleep, try Sleepnet.

SOURCES: Interviews with Jacques Clmenty, M.D., Hopital Cardiologique du Haut-Lvque, Pessac, France; Daniel Gottlieb, M.D., M.P.H., associate professor of medicine, Boston University School of Medicine; Feb. 7, 2002, New England Journal of Medicine
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