How Obstructive Sleep Apnea Affects Heart Health

Obstructive sleep apnea (OSA) is characterized by repetitive pauses in breathing during sleep, caused by intermittent collapse of the throat muscles and obstruction of the airway. Those living with OSA are at an increased risk of developing various heart problems, including poor blood flow to the heart, heart failure, and abnormal heart rhythms.

What Heart Conditions Are Linked to Obstructive Sleep Apnea?

Obstructive sleep apnea is linked to an increased risk for developing heart disease, the leading cause of death in the United States.

Heart disease is a generalized term for multiple heart conditions, of which the following are linked to OSA:

• Coronary artery disease (CAD): CAD is caused by the buildup of plaque (fatty, waxy deposits) within the coronary arteries, which supply the heart muscle with oxygen and nutrients. CAD may cause no symptoms, especially in the early stages, until a heart attack—also known as a myocardial infarction—develops.
• Arrhythmias (abnormal heart rhythms), especially atrial fibrillation (AFib): Atrial fibrillation originates in the heart’s upper chambers, causing them to “quiver” and leading to an irregular, usually rapid heart rhythm. Research has found that adults with OSA are two to four times more likely to develop atrial fibrillation than people without OSA.
• Heart failure: Heart failure describes a weakened heart that is unable to pump sufficient oxygen-and nutrient-rich blood to the body’s tissues. A large review study found the presence of OSA in individuals with heart failure to be nearly 40%.

Notably, OSA is also associated with high blood pressure (hypertension), in which the force of blood against arterial walls is elevated. Hypertension is not technically a form of heart disease; however, it is a major risk factor for heart disease.

What Pathways Link OSA to Poor Heart Health?

Obstructive sleep apnea increases one’s vulnerability to heart disease because repeated pauses in breathing can stress and eventually damage the heart muscle.

Diving a little deeper, episodes of upper airway collapse during sleep, as seen in OSA, cause the following:

• Intermittent decreases in oxygen levels (hypoxia): Upper airway collapse—when the tongue falls backward, and there is no airflow—impedes oxygen from being breathed in (inhaled).
• Activation of the sympathetic nervous system (the body’s fight-or-flight response): The brain perceives pauses in breathing as life-threatening. As a result, the sympathetic nervous system is activated, triggering the release of stress hormones that prompt a person to gasp for air.
• Marked pressure swings in the chest: Breathing in against a closed upper airway causes large drops in pressure within the chest cavity.
• Chronic sleep deprivation: The stop-and-start breathing pattern of OSA markedly impairs sleep quality and contributes to chronic sympathetic nervous system activation.

How OSA Leads to Coronary Artery Disease

Experts suspect that repeated episodes of hypoxia seen in OSA induce oxidative stress, an imbalance between reactive oxygen species and antioxidants in cells.

Oxidative stress promotes a state of low-grade inflammation (as does chronic sleep deprivation) within the body.

Sustained inflammation can lead to injury and dysfunction of the coronary arteries. which in turn, facilitates plaque formation—a precursor to cardiovascular diseases, like heart attacks and strokes.

Lastly, low oxygen levels along with the intense negative pressure that develops in the chest as a person tries inhale against a blocked airway, can hinder blood flow to the heart, thereby resulting in a heart attack.

How OSA Can Cause Arrhythmia

Sustained activation of the sympathetic nervous system from chronic lack of sleep can generate chaotic electrical activity within the heart, thereby contributing to the development of arrhythmias.

Repeated pressure fluctuations within the chest cavity, along with intermittent decreases in oxygen levels, can cause structural damage to the heart muscle, including stretching, enlargement, or remodeling of the heart’s chambers.

These structural changes in the heart muscle increase the risk of arrhythmias, especially atrial fibrillation.

How OSA Affects Heart Failure

The extreme pressure changes within the chest cavity during inhalation strain the heart muscle. Over time, this stress on the heart can worsen or cause heart failure.

Persistent activation of the sympathetic nervous system can also contribute to the development of heart failure.

How OSA Affects Hypertension

Activation of the sympathetic nervous system as a response to low oxygen levels causes marked increases in blood pressure and heart rate. Over time, persistent increases in blood pressure can cause or worsen hypertension.

Impaired sleep or sleep deprivation can also contribute to the development of hypertension.