BOSTON -- A cardiologist became curious why heart patients who had been given pacemakers were suddenly snoring less. What he found out could transform doctors' understanding of apnea and point the way to drug treatments for the sometimes dangerous sleep disorder.
Apnea sufferers stop breathing for 10 seconds to a minute or more, a condition that can rouse them hundreds of times a night. Apnea sufferers tend to snore loudly.
The condition can leave people exhausted by day and in danger of dozing off while driving. Scientists also believe apnea contributes to high blood pressure and heart disease.
But a team of French doctors, led by cardiologist Stephane Garrigue, found in a study that faster heart rates caused by pacemakers can relieve apnea.
That stands on end the prevailing theory that apnea acts on the heart. It means the heart can also act on apnea.
"In patients with normal heart rhythm, maybe it's the occasion to develop some drugs to increase the heart rate," Garrigue said.
The findings, reported in Thursday's New England Journal of Medicine, have intrigued doctors.
"If you had asked me about this, I would have said it was a long shot," said Dr. Jeffrey Drazen, a respiratory specialist and editor in chief of the journal.
Garrigue's medical team at the University of Bordeaux studied 15 heart patients who showed symptoms of sleep apnea.
Pacemakers kick in when the heart slips below a certain number of beats per minute. For the study, the researchers increased that number by 15 beats per minute. In this overdrive setting, the patients' hearts would turn on the pacemakers when the rate dropped to around 70 beats a minute.
On the overdrive setting, the average hourly number of nighttime breathing lapses dropped 61 percent, from 28 to 11.
"We were very surprised to have this kind of effect," Garrigue said.
Garrigue and other doctors suggested that the faster heart rates may be stimulating various nerves, which then prompt the brain to normalize breathing.
Up to 18 million Americans suffer from apnea.
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