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HEART Insight:
doi: 10.1097/01.HEARTI.0000286140.44586.d2
Features: Related Risk/A Good Night's Sleep Means More Than Sweet Dreams

How Sleep Apnea Affects The Cardiovascular System

Papazian, Ruth

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Imagine waking up choking and gasping for air, then catching your breath and falling back into fitful slumber – for a minute or two, until it happens again. And again. And again. A hundred or more times a night.

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That's what it's like to have sleep apnea, a potentially life-threatening sleep disorder in which tissues in the throat collapse and block the airway. Ever vigilant, the brain forces the sleeper awake enough to cough or gulp air to open the trachea up again. But then, the whole cycle starts all over again.

“Pauses in breathing can contribute to severe fatigue during the day, and can make it difficult to perform tasks that require alertness. You could crash your car, or get hurt at work,” says Nidhi S. Undevia, M.D., Medical Director of the Center for Sleep Disorders, Loyola University Health System, Maywood, Ill.

Sleep apnea is also a risk factor for such medical problems as high blood pressure, heart failure, diabetes and stroke, she adds.

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Three Types

Some 12 million Americans have sleep apnea, according to National Heart, Lung, and Blood Institute estimates. There are three types: obstructive sleep apnea (OSA), central sleep apnea (CSA) and mixed apnea, which is a combination of the other two types.

The most common is OSA. The typical OSA patient is a man over the age of 40 who is overweight and can't button the top of his shirt collar, unless it is 17 inches or larger. But OSA can affect women as well–and anyone who is overweight, has large tonsils blocking the airway or suffers chronic nasal congestion is at increased risk.

More than half of people who have OSA also have high blood pressure–and unlike most people, their blood pressure does not fall while they're asleep.

“Doctors don't know whether sleep apnea elevates blood pressure because of repeated awakenings or because of drops in oxygen levels [in the blood]. It's likely to be a combination of both,” says Daniel Norman, M.D., Fellow in Pulmonary and Critical Care at the University of California San Diego Medical Center.

OSA also stresses the heart, says Shahrokh Javaheri, M.D., Emeritus Professor of Medicine at the University of Cincinnati College of Medicine and medical director of Sleepcare Diagnostics in Mason, Ohio. Lack of oxygen and rising blood pressure both contribute to OSA related heart failure, he adds.

With CSA, airway blockage isn't the problem. It's that the brain doesn't send regular, continuous signals to the muscles of the diaphragm to contract and expand to enable you to inhale and exhale. Central sleep apnea may develop after a stroke, or may be caused by sedatives and narcotics and brain injury, explains Undevia. Heart failure patients are susceptible to developing a type of CSA called Cheyne–Stokes respiration.

Keeping oxygen levels in the blood at normal levels during sleep may lessen the severity of CSA in these patients. In a pilot study with 12 CSA patients who had heart failure, Javaheri found that a dose of acetazolamide–a mild diuretic and respiratory stimulant–one hour before bedtime reduced the number of episodes of interrupted breathing while also improving blood oxygen levels. The patients, who were given the drug over a six-day period, also felt better rested and less sleepy during the daytime. “This was only a six-day study, though,” says Javaheri, “and more research is needed to determine whether long-term use will improve heart function as well.”

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Diagnosis and Treatment

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If you always feel sleepy despite being in bed eight hours a night, or your spouse delicately suggests separate bedrooms because your snoring has become unbearable, you should ask your doctor about sleep apnea. You will most likely be referred to a sleep disorders specialist, and will need to spend a night or two in a lab hooked up to a machine that will monitor and chart your brain waves, oxygen levels, breathing and heart rate while you sleep.

“Looking at the brain wave pattern tells us whether you are asleep, and the quality of your sleep. We also look for pauses in breathing, and whether you wake up during those pauses,” says Undevia. During breathing pauses, oxygen levels are checked, as well as whether heart rate slows or becomes irregular. “Generally, five pauses in breathing an hour may be a mild case [of apnea], and 30 or more may be a severe case.”

If the test shows that you have moderate or severe sleep apnea, you will most likely be fitted for a continuous positive airway pressure (CPAP) mask to wear while you sleep.

As you inhale, an air compressor in the device creates enough pressure to produce a steady stream of air that keeps your airway open.

As an added bonus, elevated blood pressure drops significantly after using the mask for two weeks, according to a study of 46 OSA patients conducted by Norman. In his study, some patients used a pressurized CPAP mask, others a placebo mask with reduced pressure and the remaining wore a mask with supplemental oxygen without pressure. In this study, the positive pressure–and not the oxygen–had a beneficial effect on blood pressure.

Although the mask is effective, some patients complain of claustrophobia, or have trouble falling asleep while wearing it. Trying a mask with a different style or a different fit may solve the problem.

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But when someone with a mild to moderate case of sleep apnea is resistant to using the mask, there are surgical alternatives. For instance, the Pillar procedure is a minimally invasive technique that involves inserting three rods, each ¾″ long, into the roof of the mouth. Scar tissue forms around the implants, which firms and supports the roof of the mouth to prevent its collapse during sleep.

Surgical procedures can make the back of the throat larger or tissues in the nose smaller. “Using a thin, lighted scope snaked up your nose, an ear, nose and throat (ENT) surgeon will see where the blockage is,” says Undevia, “and then may recommend having your tonsils removed or correcting a deviated septum in the nose.”

Other surgical options include making the roof of the mouth smaller or removing part or all of the uvula (that round thing that hangs from the roof of your mouth in between your tonsils).

Doctors used to alleviate sleep apnea by performing a tracheostomy–cutting a hole in the windpipe–which is still an option in severe cases when CPAP does not work.

Sleep apnea isn't just snoring. Left untreated, the condition can lead to serious cardiovascular problems. Fortunately, there are several non-surgical and surgical treatment options you can discuss with your doctor.

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who is that Masked Man?

Two years ago, Gregory Hoenig, now 58, used to wake up every morning “feeling like crap.” He was drowsy and groggy and says it was “like having a hangover.”

His wife, Noreen, became “rather aggravated with my snoring, which would wake her up. She noticed that I would stop snoring, then stop breathing and she would nudge me so that I would start breathing again,” he recalls. He adds, “My loving partner turned out to be my guardian angel when she realized that I stopped breathing about four times an hour.”

Frightened, Hoenig went to the Center for Sleep Disorders at Loyola University for an overnight sleep evaluation. “They put electrodes all over your head, close to your eyes, on your chest and on your legs. They have an infrared camera on you all night to watch you while you sleep,” he explains.

When all the electrodes had been stuck in place, it was 10:30 p.m.–time for bed. The former pharmaceutical salesman says that he was able to get to sleep “pretty quickly” because, “I was a road warrior, traveling about 50 percent of the time over the last 14 years so I got used to sleeping in strange places a long time ago.”

The tests confirmed that he had sleep apnea. His doctor, Nidhi S. Undevia, recommended that he wear a CPAP mask. He spent another night at the sleep lab to get fitted with the mask; while he slept, the airflow pressure was adjusted until the pauses in his breathing stopped occurring.

“It took me about four or five days to get used to the mask. It's not natural to have something on your face, but you feel so good, so rested in the morning that it's a good trade-off,” says Hoenig.

Today, he goes to the sleep clinic a couple of times a year for follow-up. “My CPAP has a computer chip in it [from which] the doctor can get a printout that shows how often I have been using the mask. I get the impression from the doctor that non-compliance is a huge issue,” he says.

Not for him, though. “The apnea started to compromise function of my left ventricle, which can lead to heart failure if it progresses. Not developing heart failure is my motivation for using the mask. Plus how great I feel in the morning now,” Hoenig says.

“You look kind of goofy with the mask, but when it comes to any therapy–whether taking a pill or exercising–I am a big believer in following doctor's orders.”

© 2007 American Heart Association, Inc.