Links Between Sleep Apnea and Heart Failure

About 2-4 percent of adults have sleep apnea and about 1 in 3 people with heart failure also have sleep apnea. So, is there a connection between these two diseases? Here’s what to know.^1-2

What is sleep apnea?

Apnea is a medical term that means cessation of breathing. Sleep apnea is defined as periodic episodes of apnea while sleeping that last ten seconds or longer. It is clinically defined as having 10-15 apnea periods per hour of sleep.^1,3

There are three types of sleep apnea and they both cause interruptions in your sleep. I will define them all here.

Central Sleep Apnea (CSA)

Apnea is caused by periodic stoppages of your central drive to breathe. You stop breathing because the signal from your brain is blocked. This condition is a less common form of apnea, affecting 10-15 percent of people with sleep apnea. It is usually caused by some other health condition, such as certain drugs, stroke, or heart failure.

Studies show it is prevalent in 40% of people with systolic heart failure. It may also be present in some people with symptomatic diastolic heart failure. As described below, it may also cause heart failure. CSA often involves cycles of slow breathing, no breathing, and fast breathing.^1-5

Obstructive Sleep Apnea (OSA)

With CSA, apnea periods involve no drive to breathe. With OSA, you still have the drive to breathe, but inhaled air is blocked from getting to your lungs by upper airway obstruction. It may be caused by an airway that is abnormally small or large.

The soft tissue of your upper airway collapses, thereby blocking the airway. During these episodes, your body will still try to inhale, but you won’t get any air. These efforts cause awkward motions by your chest and abdomen and they may end in a snore or grunt. Then you wake up and breathe normally.

OSA is the most common form of sleep apnea. If left untreated, and like CSA, OSA may cause heart failure. The most common risk factor is obesity. This is because fat tissue relaxes during sleep, thereby narrowing (obstructing) the upper airway.

It is possible that heart failure may also be a risk factor. One theory is that this may happen when you lie flat. Fluid from your lower extremities may move to other areas of your body. If it moves to your upper airway this may narrow (obstruct) your airway. Researchers are still unsure if this theory will hold true. Therefore, they are unsure if heart failure directly contributes to OSA.^1-3,6

Combined

Some people have a combination of both CSA and OSA.

How do they cause heart failure?

Under normal circumstances, sleep has a relaxing effect on your heart, but intermittent apnea episodes prevent your heart from relaxing. This creates an environment that, over time, can be harmful to your heart. This is especially true if left undiagnosed and untreated. Over time, intermittent periods of apnea while you are sleeping can cause:

• Hypoxia. Of course, we know this is a molecule that is in the air. It is essential to life. If you are not inhaling, you are not getting oxygen to your lungs. So, this means less oxygen is getting to your tissues, including your heart tissues.
• Hypercapnia. Carbon dioxide is a waste product that must be exhaled. If you are not inhaling, it may collect in your blood. This causes high carbon dioxide levels in your arterial blood. This can make you feel fatigued during the daytime.
• Increased afterload. This is a fancy language that basically means your heart has to work harder to pump oxygenated blood through your body.
• Daytime hypertension. Your blood pressure is higher than normal while you are awake and this causes your heart to work harder, as I described in my post, “What is hypertension?”
• Loss of vagal heart rate regulation. Loss of ability of your brain to slow your heart rate down. This may cause your heart to always remain elevated. You may feel stimulated and ready for action, even while you’re trying to rest.
• Arrhythmias. Abnormal heart rhythms may develop. A common one is called atrial fibrillation.
• Cardiac remodeling. The tissues in your heart change over time.

So, the combination of these may be damaging to your heart. They can damage it in such a way as to make it a weaker pump which may cause heart failure.³

How is it diagnosed and treated?

The good news is that researchers are aware of the effects of sleep apnea and they are aware of the links between sleep apnea and heart failure. Many doctors have developed screening tools to help them recognize and diagnose patients with sleep apnea.

A diagnosis is made by a recognition of any of the following symptoms:

• Daytime sleepiness
• Morning headaches
• Apnea episodes at night
• Nighttime snoring (often this is recognized by the person you are sleeping next to)
• Trouble focusing during the day
• Irritability

Observation of these symptoms can lead to a sleep study. Sleep studies can be done in a clinical setting which is probably the most accurate. During these studies, a technician can see if one of the machines (described below) will prevent apnea. Your doctor may also order a home sleep study. These are simpler tests as you can do them in the comfort of your own home.⁷

Once diagnosed, proper treatment can begin. CSA is often treated by treating the underlying condition which may be heart failure itself. In many instances, treatment for heart failure can cure the CSA.

OSA and CSA can both be treated with:^1-3,7

• CPAP. A device that maintains a constant pressure in your airways. This acts as a splint to keep your upper airway from collapsing. This prevents apnea and also helps to maintain normal oxygen levels.
• BiPAP. This is a device that has two pressures. The first pressure is the same as CPAP. It splints your airways to keep them from collapsing. This helps you maintain normal oxygen levels while sleeping. The second pressure causes you to take in a breath. It assures your ventilation remains normal while sleeping and makes sure you continue to exhale carbon dioxide while you are sleeping.
• Supplemental oxygen. This is where you inhale oxygen while sleeping. This can be done by adding supplemental oxygen to your CPAP or BiPAP device. Some people may also benefit from wearing daytime supplemental oxygen. This can be accomplished by wearing a simple device called a nasal cannula.
• Other. Your doctor may recommend oral devices. In some cases, your doctor may recommend surgery. Obesity is a common cause of OSA. If suspected, your doctor may recommend losing weight. Alcohol can relax your upper airway and contribute to OSA. So, your doctor may recommend you avoid drinking alcohol.

How to move forward

Sleep apnea appears to be a common condition in the heart failure community. The good news is that doctors are aware of this link and they have developed screening strategies to properly diagnose it. A proper diagnosis is what helps doctors determine the best treatment strategies for helping you live better and longer despite your diagnosis.