The link between cardiac autonomic activity and sleep delta power is altered in men with sleep apnea-hypopnea syndrome

Abstract

We hypothesize that sleep apnea-hypopnea alters interaction between cardiac vagal modulation and sleep delta EEG. Sleep apnea-hypopnea syndrome (SAHS) is related to cardiovascular complications in men. SAHS patients show higher sympathetic activity than normal subjects. In healthy men, non-rapid eye movement (NREM) sleep is associated with cardiac vagal influence, whereas rapid eye movement (REM) sleep is linked to cardiac sympathetic activity. Interaction between cardiac autonomic modulation and delta sleep EEG is not altered across a life span nor is the delay between appearances of modifications in both signals. Healthy controls, moderate SAHS, and severe SAHS patients were compared across the first three NREM-REM cycles. Spectral analysis was applied to ECG and EEG signals. High frequency (HF) and low frequency (LF) of heart rate variability (HRV), ratio of LF/HF, and normalized (nu) delta power were obtained. A coherency analysis between HF(nu) and delta was performed, as well as a correlation analysis between obstructive apnea index (AI) or hypopnea index (HI) and gain, coherence, or phase shift. HRV components were similar between groups. In each group, HF(nu) was larger during NREM, while LF(nu) predominated across REM and wake stages. Coherence and gain between HF(nu) and delta decreased from controls to severe SAHS patients. In SAHS patients, the delay between modifications in HF(nu) and delta did not differ from zero. AI and HI correlated negatively with coherence, while HI correlated negatively with gain only. Apneas-hypopneas affect the link between cardiac sympathetic and vagal modulation and delta EEG demonstrated by the loss of cardiac autonomic activity fluctuations across shifts in sleep stages. Obstructive apneas and hypopneas alter the interaction between both signals differently.

Sleep and cardiovascular regulation

“…For example, aging is associated with a reduction in delta activity and an increase in the LF/HF ratio during NREM sleep [8,30]. Similarly, a number of disorders have been identified that are characterized by low levels of delta activity and high sympathovagal balance, including insomnia [28], fibromyalgia [41], sleep apnea [29], and alcohol dependence [26]. Further, acute stress imposed before sleep has been shown to reduce the amount of delta activity and increase sympathovagal balance during sleep [21].…”

Characterization of physiological networks in sleep apnea patients using artificial neural networks for Granger causality computation

“…Modifications in the heart activity was characterized by the RR intervals in normal patients, and reading of visual inspection revealed that the fluctuations of high frequency of the CS (HF reflect cardiac parasympathetic activity) are related with δ frequency band of the brain signals. In 2006, this analysis was extended to male patients diagnosed with sleep apnea, reveling that the respiratory disorders in the sleep, affect the fluctuations of the heart activity [11]. This affectation is reflected by anomalies in the relation between the sympathetic cardiac modulation, the vagal modulation and the δ band subsystem.…”

Interaction between sleep EEG and ECG signals during and after obstructive sleep apnea events with or without arousals

“…These episodes of obstruction are associated with recurrent oxyhemoglobin desaturation and arousals from sleep. Recently, effects of OSA on the interaction between cardiac autonomic control and EEG have been studied [1][2]. Jurysta et al [2] reported that in patients with severe obstructive sleep apnea syndrome (OSAS), coherence between the autonomic cardiac fluctuations and delta sleep EEG was decreased due to a loss of heart rate variability (HRV) during shifts in sleep stages (non REM and REM).…”