The Effects of Sleep Apnoea on Your Heart

Can sleep apnoea affect heart health? 

Obstructive sleep apnoea has become a common health problem nowadays. It is often associated with signs and symptoms such as excessive daytime somnolence and cognitive impairment, as well as cardiovascular and metabolic morbidity. There are recent reports that sleep apnoea can affect heart health. Is this true?

To answer this question let us first review the basic mechanisms linking obstructive sleep apnoea to heart disease. According to several studies, obstructive sleep apnoea can indeed cause myocardial and arterial damage and thus can lead to the progression of heart disease. This can be due to the resulting hypoxemia from sleep fragmentation, intrathoracic pressure swings and recurrent hypercapnia. Aside from hypoxia, other contributing factors are sympathetic nervous system overactivity, systemic inflammation and oxidative stress leading to endothelial dysfunction and, possibly, metabolic dysfunction.

Sympathetic nervous system overactivity is due to the increased level of catecholamines in obstructive sleep apnoea. CPAP is said by recent studies to effectively lower elevated catecholamine levels in OSA. Sympathetic overactivity is also the culprit for hypertension.

Inflammation is another contributory factor to heart disease. It is said that in OSA patients, there is impaired endothelial function and signs of early atherosclerosis, such as increased carotid intima-media thickness in OSA which may improve with effective CPAP therapy. This may be attributed to increase in inflammation in patients with OSA.

Patients with OSA are also exposed to oxidative stress. It is said that OSA-related repetitive episodes of hypoxia and re-oxygenation have generally been associated with increased production of reactive oxygen species and, thus, are thought to promote oxidative stress. Obstructive sleep apnoea is said to also give rise to metabolic dysfunction in the form of insulin resistance and dyslipidemia.

Given these facts, there is a need for larger studies to look for other factors that may contribute to morbidity and mortality associated with sleep apnoea. The changes associated with sleep apnoea such as sleep fragmentation, intrathoracic pressure swings and recurrent hypercapnia are enough to trigger a harmful cascade that can bring about sympathetic nervous system overactivity, systemic inflammation and oxidative stress leading to endothelial dysfunction and, possibly, metabolic dysfunction. Thus experts should encourage treatment of sleep apnoea as soon as possible so that complications can be prevented.

Reference:

Lévy P, Ryan S, Oldenburg O, Parati G. Sleep apnoea and the heart. Eur Respir Rev. 2013 Sep 1;22(129):333-352.

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