Sleep apnoea as an independent risk factor for cardiovascular disease: current evidence, basic mechanisms and research priorities
ABSTRACT Considerable evidence is available in support of an independent association between obstructive sleep apnoea syndrome (OSAS) and cardiovascular disease, which is particularly strong for systemic arterial hypertension and growing for ischaemic heart disease, stroke, heart failure, atrial fibrillation and cardiac sudden death. The pathogenesis of cardiovascular disease in OSAS is not completely understood but likely to be multifactorial, involving a diverse range of mechanisms including sympathetic nervous system overactivity, selective activation of inflammatory molecular pathways, endothelial dysfunction, abnormal coagulation and metabolic dysregulation, the latter particularly involving insulin resistance and disordered lipid metabolism. The present report, which arose out of a European Union Cooperation in the field of Scientific and Technical Research (COST) action on OSAS (COST B26), reviews the current evidence for an independent association and proposes research priorities to identify the underlying mechanisms involved, with a view to identifying novel therapeutic strategies. Large-scale collaborative studies of carefully defined patient populations with obstructive sleep apnoea syndrome, adequately controlled for potential confounders, are needed. Such studies carry the prospect of evaluating potential interactions between different basic mechanisms operating in obstructive sleep apnoea syndrome and cardiovascular disease, and interactions with other related disorders, such as obesity, diabetes and dyslipidaemia. Furthermore, translational studies involving cell culture and animal models linked to studies of obstructive sleep apnoea syndrome patients are necessary to integrate basic mechanisms with the clinical disorder.
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ABSTRACT: Objective The pathophysiological basis of obstructive sleep apnea (OSA) is not completely understood and likely varies among patients. In this regard, some patients with OSA do not exhibit hypoxemia. We aimed to analyze the clinical, sleep, and autonomic features of a group of patients with severe OSA without hypoxia (OSA-h) and compare to OSA patients with hypoxia (OSA+h) and controls. Methods Fifty-six patients with OSA-h, 64 patients with OSA+h, and 44 control subjects were studied. Clinical and sleep features were analyzed. Besides, time- and frequency-domain heart rate variability (HRV) measures comprising the mean R-R interval, the standard deviation of the RR intervals (SDNN), the low frequency (LF) oscillations, the high frequency (HF) oscillations, and the LF/HF ratio, were calculated across sleep stages during a one-night polysomnography. Results OSA-h patients had a lower body mass index, a lower waist circumference, lower apnea duration, and a higher frequency of previous naso-pharyngeal surgery when compared to OSA+h patients. In terms of heart rate variability, OSA+h had increased LF oscillations (i.e., baroreflex function) during N1-N2 and rapid eye movement (REM) sleep when compared to OSA-h and controls. Both OSA+h and OSA-h groups had decreased HF oscillations (i.e., vagal inputs) during N1-N2, N3 and REM sleep when compared to controls. The LF/HF ratio was increased during N1-N2 and REM sleep, only in patients with OSA+h. Conclusions Patients with OSA-h exhibit distinctive clinical, sleep, and autonomic features when compared to OSA with hypoxia. Significance OSA is a heterogeneous entity. These differences must be taken into account in future studies when analyzing therapeutic approaches for sleep apnea patients.Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 09/2014; 125(9). DOI:10.1016/j.clinph.2014.01.029 · 2.98 Impact Factor
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ABSTRACT: Background Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory mediator used as a novel marker for vascular specific inflammation, atherosclerosis and cardiovascular risks in humans. Both chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are associated with frequent cortical arousals on polysomnography, and increased activation of inflammatory cells and molecular mechanisms associated with atherosclerosis and cardiovascular complications. Objective To study the relation between Lp-PLA2 level as a marker of cardiovascular risks and arousal index in patients with OSA, COPD and overlap syndrome (COPD + OSA). Patients and methods Sixty participants were recruited, divided into four groups (15 in each group) based on their polysomnographic and spirometric data; group I (normal), group II (OSA), group III (COPD) and group IV (overlap syndrome). Fasting serum samples were used to estimate lipid profile and Lp-PLA2 concentrations. Results The apnea–hypopnea, arousal, desaturation indices, lipid profile and Lp-PLA2 levels were significantly increased in all patient groups compared to control. The arousal index and Lp-PLA2 level were significantly increased in overlap syndrome more than OSA and COPD patients. Lp-PLA2 level was independent predictor of arousal index in all patient groups. Conclusions Patients with overlap syndrome have a higher arousal index and Lp-PLA2 level hence more cardiovascular risks than either OSA or COPD alone. The Lp-PLA2 level may be used as an independent predictor of cardiovascular risks in patients with OSA, COPD and overlap syndrome.04/2014; 63(2). DOI:10.1016/j.ejcdt.2014.01.012
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ABSTRACT: Obstructive sleep apnoea is a highly prevalent but under-diagnosed disorder. The gold standard for diagnosis of obstructive sleep apnoea is inpatient polysomnography. This is resource intensive and inconvenient for the patient, and the development of ambulatory diagnostic modalities has been identified as a key research priority. SleepMinder (BiancaMed, NovaUCD, Ireland) is a novel, non-contact, bedside sensor, which uses radio-waves to measure respiration and movement. Previous studies have shown it to be effective in measuring sleep and respiration. We sought to assess its utility in the diagnosis of obstructive sleep apnoea. SleepMinder and polysomnographic assessment of sleep-disordered breathing were performed simultaneously on consecutive subjects recruited prospectively from our sleep clinic. We assessed the diagnostic accuracy of SleepMinder in identifying obstructive sleep apnoea, and how SleepMinder assessment of the apnoea-hypopnoea index correlated with polysomnography. Seventy-four subjects were recruited. The apnoea-hypopnoea index as measured by SleepMinder correlated strongly with polysomnographic measurement (r = 0.90; P ≤ 0.0001). When a diagnostic threshold of moderate-severe (apnoea-hypopnoea index ≥15 events h(-1) ) obstructive sleep apnoea was used, SleepMinder displayed a sensitivity of 90%, a specificity of 92% and an accuracy of 91% in the diagnosis of sleep-disordered breathing. The area under the curve for the receiver operator characteristic was 0.97. SleepMinder correctly classified obstructive sleep apnoea severity in the majority of cases, with only one case different from equivalent polysomnography by more than one diagnostic class. We conclude that in an unselected clinical population undergoing investigation for suspected obstructive sleep apnoea, SleepMinder measurement of sleep-disordered breathing correlates significantly with polysomnography.Journal of Sleep Research 11/2012; DOI:10.1111/j.1365-2869.2012.01056.x · 2.95 Impact Factor