Sleep disorders

Bradycardia and associated obstructive sleep apnea syndrome

Bradycardia is a change in the heart rate that develops in connection with a decrease in the automatism of the sinus node, and is characterized by a decrease in the number of heartbeats to 50–30 beats per minute. It has been studied and proven that the cause of bradycardia in patients is the presence of an accompanying obstructive sleep apnea syndrome.

Bradycardia is dangerous in terms of the appearance of periodic sudden loss of consciousness ( Morgagni – Adams -Stokes syndrome), the development of chronic circulatory failure and sudden cardiac arrest. In severe forms of bradycardia (heart rate less than 40 beats per minute and cardiac arrest for more than two seconds), a pacemaker is required.

Cardiac arrhythmias (bradycardia, tachycardia, atrial fibrillation, extrasystole) are common in patients with obstructive sleep apnea. It has been noted that the frequency of these disorders increases with an increase in the severity of the underlying disease and, accordingly, the degree of hypoxemia that accompanies this disease. Hypoxemia is a typical sign of obstructive sleep apnea associated with episodes of apnea or hypopnea and is cyclical. If the compensatory mechanisms are violated, the patient develops severe hypoxemia during the entire time of sleep. It was at the moment of cessation of breathing in patients that a decrease in heart rate was recorded – bradycardia, which in this case is due to gas exchange disorders during an apnea attack.

Regular attacks of bradycardia were found in 18% of patients with sleep apnea syndrome. Conversely, in patients with nocturnal episodes of bradycardia, obstructive sleep apnea syndrome was diagnosed in 68% of cases. It has been observed that 59% of patients who had previously had a pacemaker implanted for severe bradycardia, such as 2nd and 3rd degree AV block, had concomitant obstructive sleep apnea. Thus, there is a direct relationship between obstructive sleep apnea and the presence of bradycardia.

The appearance of bradycardia in the syndrome of obstructive sleep apnea is also explained by an imbalance in the activity of the sympathetic and parasympathetic nervous systems. Moreover, more pronounced changes are observed in patients with an apnea- hypopnea index of more than 20 and depend on the body mass index. Bradycardia in patients with sleep apnea is highly variable. In some cases, there is a development of progressive bradycardia, up to asystole, which is abruptly replaced by tachycardia after the resumption of breathing. Severe bradycardia causes a drop in blood perfusion, which, in combination with desaturation , increases the risk of hypoxic organ damage.

Treatment of bradycardia is aimed at treating the underlying disease that provoked its appearance. If this type of arrhythmia is not associated with any heart disease, does not occur in the waking state, and disappears after the obstructive sleep apnea syndrome is eliminated, then CPAP therapy – non-invasive assisted ventilation of the lungs with positive constant pressure will be the main method of treating nocturnal bradycardia attacks. The use of CPAP therapy in such patients even makes it possible to avoid a complex operation – the implantation of a pacemaker. Conversely, an incorrect interpretation of the cause of such heart rhythm disturbances, interpreting them as a manifestation of sick sinus syndrome, leads to unreasonable implantation of an artificial pacemaker.

At present, improved CPAP devices Prisma Line from the new line of Weinmann – Loewenstein (Germany) have been developed. Their use allows the most effective and comfortable treatment of the entire spectrum of respiratory disorders in patients with obstructive sleep apnea syndrome.

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