SLEEP APNEA AND HEART DISEASE: Is there a connection?
By: Hector F Lozano, MD FACC
Florida Heart Group
Sleep apnea and its hallmark — loud snoring — have long been viewed as an annoyance. Just ask someone who has to share a room with a loud snorer if sleep apnea is a problem. But there's growing evidence that sleep apnea isn't just annoying; it can be bad for your heart, too.
You have probably heard about the usual problems associated with sleep apnea, such as excessive day-time sleepiness and feeling tired during the day. But sleep apnea can have more serious health effects, such as increasing your risk of high blood pressure and possibly heart failure, stroke, an abnormal heart rhythm (atrial fibrillation) and heart attacks.
What is sleep apnea?
Sleep apnea is a sleep disorder in which your breathing stops or gets shallow temporarily. These pauses in your breathing can occur dozens of times each hour while you sleep. The most frequent type of sleep apnea is due to obstruction of the airway while asleep. This form of the disease is, in turn, closely related to body weight. It is believed that a good portion of the obesity-related heart disease might be attributed to sleep apnea.
How does sleep apnea cause cardiovascular disease?
Sleep apnea may be linked to heart disease because of the drop in oxygen that occurs during sleep apnea. When the oxygen level drops, carbon dioxide level increases. Your brain senses trouble and tells your body to release adrenaline-like substances into the bloodstream which increases blood pressure, thus the link to sleep apnea and high blood pressure. Because of low oxygen, your body also releases other substances that can eventually damage the endothelium (inner lining of your body's blood vessels), and it is this damage that might eventually cause or worsen high blood pressure and other forms of cardiovascular disease or heart problems.
Which cardiovascular problems may be related to sleep apnea?
High blood pressure
Sudden drops in blood-oxygen levels that occur during sleep apnea increase blood pressure and strain the cardiovascular system. About half the people with sleep apnea develop hypertension (high blood pressure). The association between sleep apnea and hypertension is the most consistently documented so far in clinical studies. Nonetheless, the only thing we can say for certain right now is that sleep apnea increases your risk of high blood pressure, not that it causes it. While hypertension itself increases the risk of various forms of heart disease, there's speculation that sleep apnea also plays a more direct role in heart disease.
Sleep apnea may increase the risk of heart failure because of the swings in blood pressure that occur during sleep apnea. This, combined with reductions in oxygen to heart tissue, might damage the heart muscle over time. If you already have heart failure, this repeated stress to the heart might make things worse.
Arrhythmias (Heart rhythm problems)
Arrhythmias occur when the electrical impulses in your heart don't function properly, causing your heart to beat too fast, too slow or irregularly. One of the more common types of arrhythmias thought to be associated with sleep apnea is atrial fibrillation. This occurs when the heart's two upper chambers (the atria) beat chaotically and out of coordination with the two lower chambers (the ventricles) of the heart. Atrial fibrillation is a major risk factor to develop a stroke.
Another less common type of arrhythmia is bradycardia (too slow a heart rate) sometimes leading to episodes of asystole (a pause in the heart beat) wherein your heart just stops beating altogether for as long as the oxygen content of the blood stays under a critical level (usually a few seconds at a time). It's unclear how sleep apnea might increase the risk of arrhythmias, but the increase in blood pressure may play a big role.
Despite the seriousness of the heart rhythm abnormalities described above, no definitive link between sleep apnea and sudden cardiac death has been established.
Coronary artery disease
Coronary artery disease is caused by the gradual buildup of fatty deposits in your coronary arteries (atherosclerosis). As the deposits (plaques) slowly narrow your coronary arteries, your heart muscle receives less blood. Eventually, diminished blood flow may cause chest pain (angina), shortness of breath or other symptoms. A complete blockage can cause a heart attack. Sleep apnea may increase your risk of coronary artery disease because of the swings in blood pressure that occur during sleep apnea. This, combined with dips in oxygen levels in your blood, might make your blood vessels more susceptible to damage.
A stroke occurs when the blood supply to a part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and nutrients. Within a few minutes, brain cells begin to die. It's thought that the association of sleep apnea with atrial fibrillation and damage to your blood vessels, possibly caused by blood pressure and oxygen changes from sleep apnea, might make you more prone to a stroke.
How to prevent cardiovascular disease associated with sleep apnea?
Get evaluated for sleep apnea
Seek an evaluation from an accredited sleep center if your snoring is loud enough to disturb your sleep or that of others, you experience shortness of breath that wakes you up, you experience excessive daytime sleepiness, or your partner says that you stop breathing during sleep. If you have heart disease and any of the above apply to you, getting evaluated for sleep apnea may be especially important.
Most accredited, qualified sleep centers are run by physicians specialized in Pulmonary Medicine (Pulmonologists or "Lung Doctors") with additional training in diagnosis and treatment of sleep disorders.
Try simple preventive measures
Sleeping on your side, weight loss and avoiding alcohol before bed are all proven steps you can take to reduce sleep apnea. Sometimes dental devices that keep the jaw stable during sleep can help milder cases of sleep apnea.
Consider continuous positive airway pressure (CPAP)
If you have moderate to severe sleep apnea, you may benefit from a machine that delivers air pressure through a mask placed over your nose while you sleep. With CPAP (SEE-pap), the air pressure is increased just enough to keep your upper airway passages open, preventing apnea and snoring. Current CPAP devices are user-friendly and well-tolerated, especially if fitted to your individual needs by the sleep disorders specialist.
Be vigilant if you have sleep apnea
You should carefully monitor your health, such as regularly checking your blood pressure if you have sleep apnea. Also, if you ever experience chest pain or palpitations after waking up at night, get checked out.
At Florida Heart Group we are very aware of the link between sleep apnea and heart disease and frequently refer patients for evaluation and therapy of this condition as part of a comprehensive approach to treatment of heart disease.
If you or someone you love have been diagnosed with sleep apnea and wonder whether it has had any cardiovascular consequences we will be glad to help you detect early and treat them appropriately before they cause any permanent damage to your health.