Feb. 11, 2003 -- A sleep breathing disorder may actually contribute to heart problems rather than just being a result of them. New research suggests that people who suffer from a particular form of sleep apnea often have more severe heart rhythm abnormalities than others who sleep normally.
Sleep apnea occurs when breathing stops for 10 seconds or more during sleep, which can cause oxygen levels to drop in the bloodstream. People who have severe sleep apnea have 30 more of these breathing interruptions in an hour, while people with milder forms of the condition may have them about half as often.
There are two different types of sleep apnea. Obstructive sleep apnea (OSA) is the most common form of the condition and is the result of a blocked airway that prevents the person from breathing normally. OSA can usually be treated with a breathing device or lifestyle modifications.
But another, more difficult to treat form of the condition, known as central sleep apnea (CSA), is most frequently associated with heart failure. This type is caused by a periodic failure of the brain to trigger the body's normal breathing reflex.
In the study, published in the Feb. 10 Circulation: Journal of the American Heart Association, researchers evaluated the sleeping patterns of 47 people who had an impaired pumping action of the heart but did not have full-blown heart failure. They found that more than half of the patients had CSA, and 36% of them had a severe form. About 5% had the obstructive form of sleep apnea.
But researchers also found that those patients who had CSA also had more evidence of heart rate irregularities than those who didn't have sleep apnea.
"Previous studies have shown that heart failure patients often have central sleep apnea, and that those with central sleep apnea are more likely to develop abnormal and dangerous heart rhythms," says researcher Virend Somers, MD, PhD, a cardiologist at the Mayo Clinic in Rochester, Minn., in a news release. "Now we know many patients have central apnea and associated heart rhythm abnormalities long before they develop any outward manifestation of heart pumping dysfunction."
"In this instance we are now finding that central sleep apnea, which has been previously understood as a symptom of heart failure, may contribute to the development of heart failure in people at risk," says Somers.
Researchers say the findings suggest that CSA may be a potential risk factor for heart failure and more study is needed to develop effective treatments to prevent further damage in people with impaired heart function.
"We have good treatments for obstructive apneas to keep the airway open, but central apnea treatments are still mostly experimental," says Somers.