Heavy Snoring Can Cause Carotid Artery Atherosclerosis

Do you snore heavily? Loud snoring is one of the signs of obstructive sleep apnoea. Sleep apnoea is a medical condition wherein there are pauses in breathing and reduction of ventilation during sleep. Sleep apnoea is becoming a common chronic disorder nowadays, affecting people of all ages. This is why sleep apnoea needs to be treated and prevented as soon as possible.

Snoring results from sleep apnoea due to a blockage of the upper airways during sleep. This is a result of the vibration of pharyngeal walls and associated structures.

Earlier studies have noted that habitual snoring and obstructive sleep apnoea are associated with cerebrovascular disease. One researcher (Hedner et. al) hypothesized that oscillatory pressure waves originating in the upper airway during snoring may be transmitted through the surrounding tissues to the carotid artery wall. The proximity of the carotid bifurcation to the lateral pharyngeal wall is such that it is likely to be exposed to these vibrations. Animal studies have confirmed that vibration from snoring can be detected at the carotid artery wall and also within the artery lumen in rabbits. The problem is that exposure to vibratory stimuli can cause pathologic damage to arterial wall endothelial cells, which may trigger an inflammatory cascade leading to early changes of atherosclerosis. Thus it can be deduced that that exposure to chronic snoring vibrations may cause carotid artery endothelial damage, thus contributing to the pathogenesis of carotid artery atherosclerosis.

A study from Lee et. al in 2008 aimed to establish if snoring per se constitutes a risk factor for the presence of carotid atherosclerotic plaque. This observational cohort study, published in the journal Sleep, examined volunteer samples in a sleep laboratory. In this study, one hundred ten (110) volunteers (snorers and nonsnorers with only mild, nonhypoxic obstructive sleep apnoea hypopnoea syndrome) underwent polysomnography with quantification of snoring, bilateral carotid and femoral artery ultrasound with quantification of atherosclerosis, and cardiovascular risk factor assessment. Subjects were categorized into 3 snoring groups: mild (0%–25% night snoring), moderate (> 25%–50% night snoring), and heavy (> 50% night snoring).

The results revealed that the prevalence of carotid atherosclerosis was 20% with mild snoring, 32% with moderate snoring, and 64% with heavy snoring (P < 0.04, Χ2). After adjustment for age, sex, smoking history, and hypertension, heavy snoring was significantly associated with carotid atherosclerosis (odds ratio 10.5; 95% confidence interval 2.1–51.8; P = 0.004) but not with femoral atherosclerosis.

There are some reports that hypoxia or reduced oxygen levels at night may be contributory to the development of atherosclerotic plaques on the blood vessel walls of patients with obstructive sleep apnoea. Maybe this was a contributing factor, though the authors of the study examined other factors, as they claimed that measures such as the oxygen desaturation index and hypoxic sleep time did not emerge as significant risk factors for carotid atherosclerosis. More studies are really needed to establish the contributing factors that may lead to carotid atherosclerosis in patients with sleep apnoea.

The authors of this study merely supported their hypothesis that snoring vibration transmission is one of the pathophysiologic mechanisms associated with the development of carotid atherosclerotic plaque. Thus snoring should be prevented in people with high risk factors for atherosclerosis.

Reference:

Lee SA, Amis TC, Byth K, Larcos G, Kairaitis K, Robinson TD, Wheatley JR. Heavy snoring as a cause of carotid artery atherosclerosis. Sleep. 2008 Sep;31(9):1207-13.

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