THE EFFECT OF NOCTURNAL HYPOXEMIA IN OBSTRUCTIVE SLEEP APNEA SYNDROME ON MYOCARDIAL ELECTRICAL INSTABILITY AND THE RISK OF GASTRIC ARRHYTHMIAS

Abstract

Obstructive sleep apnea syndrome (OSAS) has long gone beyond a highly specialized somnological problem, having transformed into a significant risk factor for cardiovascular mortality. Epidemiological data indicate an alarming trend: in patients with severe forms of respiratory disorders, the peak of sudden cardiac death shifts to the night hours, which directly correlates with cycles of apnea and subsequent desaturation. Despite the evidence of a clinical link, the exact mechanisms by which nocturnal hypoxemia destabilizes the electrical activity of the myocardium remain the subject of active research and debate. This article analyzes the totality of data on the effect of intermittent hypoxia on the electrophysiological properties of the heart, trying to distinguish the contribution of various pathogenetic links.

The discussion focuses on pathophysiological cascades mediating the arrhythmogenic effect. The key trigger is not so much mechanical obstruction as cyclic fluctuations in oxygen partial pressure and subsequent reoxygenation. This process initiates a complex response of the body: from activation of peripheral chemoreflections and sudden surges of the sympathetic nervous system at the time of microarousal to systemic oxidative stress, leading to damage to ion channels of cardiomyocytes. Mechanical factors deserve special attention, such as significant drops in intrathoracic pressure, which create additional stress on the ventricular walls and provoke the phenomenon of mechanical-electrical feedback.

The paper systematizes information about electrocardiographic markers of instability, which have prognostic value. Special emphasis is placed on the QT interval variance and Tp-e/QT ratio, which reflect the spatial heterogeneity of repolarization and serve as independent predictors of life-threatening events. An analysis of clinical observations confirms that the severity of nocturnal desaturation (saturation time <90%) often correlates with the frequency of ventricular extrasystoles and tachycardia more significantly than the classical apnea-hypopnea index.

The effectiveness of pathogenetic therapy remains controversial. Although CPAP therapy eliminates upper respiratory tract obstruction, its effect on reducing the risk of sudden death is ambiguous and critically depends on treatment adherence and the residual apnea index. In conclusion, the need for deep integration of somnological screening into the daily practice of managing arrhythmological patients is substantiated. Correction of hypoxemia is considered not as an auxiliary measure, but as an important, potentially life-saving component of the prevention of fatal ventricular arrhythmias.