Sleep Apnoea and the Heart
Overview
Symptoms of sleep apnoea
When to see a cardiologist
Complications of sleep apnoea
Overview of Sleep Apnoea and the Heart
Obstructive sleep apnoea is a condition that causes disturbed sleep due to breathing difficulties, which may be noticeable as heavy snoring, sometimes interrupted by episodes that seem like choking. Sufferers may wake many times overnight without realising it, and with no memory of these events the next morning. The symptoms caused by sleep apnoea may be subtle and increase very slowly over time so that they may easily be missed. Often it is only when a partner mentions the choking episodes that a diagnosis is made.
Over the long term, however, sleep apnoea has many knock-on effects on the heart: the continuous wake / sleep / wake / sleep cycle has serious effects on stress hormone levels and on blood pressure. People with sleep apnoea are at higher risk of hypertension, ischaemic heart disease (heart attacks and angina), and arrhythmias such as atrial fibrillation. Many of these conditions can only be successfully treated in a sleep apnoea sufferer by diagnosis and treatment of the underlying sleep apnoea problem.
Symptoms of Sleep Apnoea
Sleep apnoea may cause very few symptoms if the disease is mild. However in more severe cases it can lead to all the symptoms you would usually associate with poor sleep: tiredness and lethargy; easy dosing or sleeping during the day. The Epworth Sleepiness Scale questionnaire can be useful to measure the degree of daytime sleepiness. In general, people with a low Epworth score have a low chance of having severe sleep apnoea, but exceptions to this general rule to exist. The STOP BANG questionnaire is an alternative way to identify people at high risk of sleep apnoea and is less reliant on the symptoms of sleepiness.
Other less obvious symptoms of sleep apnoea include a morning headache (related to increased levels of carbon dioxide overnight) and many sufferers describe waking multiple times overnight to pass water.
Many people with sleep apnoea, however, only become aware of it when they develop one of the complications of the condition.
When to See a Cardiologist
If you are concerned that you may have sleep apnoea or one of it’s complications, then a cardiologist will be able to arrange tests to confirm the condition.
If you already have a diagnosis of OSA and are worried that it is contributing to other conditions such as atrial fibrillation, arrhythmia, hyertension, or ischaemic heart disease (or that you are at risk of these conditions due to OSA) then a cardiologist can help you address this and may be able to suggest treatments for other aspects of your medical history to reduce your risk overall. Sometimes these treatments may be lifestyle changes, but medications may be recommended, for example to treat hypertension or hyperlipideamia (high cholesterol) that is also contributing to the overall cardiac risk.
Complications of Sleep Apnoea
Intermittent airway obstruction is common in sleep apnoea, and this leads to large swings in blood pressure and stress hormones overnight, when the body would usually be in a “rest and recovery" phase. While some of the complications of sleep apnoea are due to the direct effects of lack of refreshing sleep, therefore, other complications are due to abnormally high circulating levels of adrenaline and other stress hormones.
Sleep apnoea can be a direct cause of high blood pressure. This, plus other hormonal changes related to the condition add up to a 30% increase in the risk of having a heart attack; the risk of stroke is more than double in middle aged men with sleep apnoea compared to those without the condition. People with sleep apnoea are between two and four times more likely than those without the condition to develop heart rhythm problems such as ectopic beats or atrial fibrillation.
It is very common for people with sleep apnoea to be unaware of the condition, or aware that there is a problem, but to put off doing anything about it, until they suffer one of these other severe complications.