Diastolic dysfunction in controlled hypertensive patients with mild-moderate obstructive sleep apnea

Obstructive sleep apnea and hypertension; critical overview

Obstructive sleep apnea (OSA) and hypertension are two important modifiable risk factors for cardiovascular disease and mortality. Numerous studies have highlighted the interplay between these two conditions. We provide a critical review of the current literature on the role of the OSA as a risk factor for hypertension and its effect on blood pressure (BP). We discuss several key topics: the effect of OSA on nocturnal BP, BP response to continuous positive airway pressure (CPAP) treatment, CPAP effect on BP in refractory hypertension, the role of OSA in BP variability (BPV), and maladaptive cardiac remodeling mediated by OSA's effect on BP. Finally, we discuss the unique aspects of ethnicity and social determinants of health on OSA with a focus on Asian populations and the disparity in BP control and cardiovascular outcomes.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Screening of plasma exosomal lncRNAs to identify potential biomarkers for obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is highly prevalent, but frequently undiagnosed. The existing biomarkers of OSA are relatively insensitive and inaccurate. Long non-coding RNAs (lncRNAs) have no protein-coding ability but have a role in regulating gene expression. They are stably expressed in exosomes, easily and rapidly measurable. Changes in expression of exosomal lncRNAs can be useful for disease diagnoses. However, there are few reports on the association of exosomal lncRNAs with OSA. We aimed to investigate the exosomal lncRNA profiles to establish the differences between non-OSA, OSA with or without hypertension (HTN) and serve as a potential diagnostic biomarker.

Methods

This diagnostic test included 63 participants: [normal control (NC) =25], (OSA =23), and (HTN-OSA =15). Expression profiling of lncRNAs in isolated exosomes was performed through high-throughput sequencing in 9 participants. Subsequently, OSA/HTN-OSA related lncRNAs were selected for validation by droplet digital polymerase chain reaction (ddPCR), receiver operating characteristic (ROC) curves were used to determine the diagnostic value. The reliabilities of the screened gene were further validated in another independent cohort: (NC =10), (OSA mild =10), (OSA moderate =11), and (OSA severe =10), the correlation between clinical features and its expression was analyzed. The MiRanda software was used to predict the binding sites of interaction between microRNA (miRNA) and target genes regulated by screened lncRNA.

Results

We identified the differentially expressed lncRNAs and mRNAs in plasma exosomes of the NC, OSA, HTN-OSA groups. Most pathways enriched in differentially expressed lncRNAs and mRNAs had previously been linked to OSA. Among them, ENST00000592016 enables discrimination between NC and OSA individuals [area under curve (AUC) =0.846, 95% confidence interval (CI): 0.72–0.97]. The severity of OSA was associated with changes in the ENST00000592016 expression. Furthermore, ENST00000592016 affected the PI3K-Akt, MAPK, and TNF pathways by regulating miRNA expressions.

Conclusions

This is the first report about differential expression of lncRNA in OSA and HTN-OSA exosomes. ENST00000592016 enables discrimination between NC and OSA individuals. This work enabled characterization of OSA and provided the preliminary work for the study of biomarker of OSA.

Is myocardial strain an early marker of systolic dysfunction in obstructive sleep apnoea? Findings from a meta-analysis of echocardiographic studies

AIM

We investigated the association between obstructive sleep apnoea (OSA) and subclinical systolic dysfunction through a meta-analysis of echocardiographic studies that provided data on left ventricular (LV) mechanics as assessed by global longitudinal strain (GLS).

DESIGN

The PubMed, OVID-MEDLINE, and Cochrane library databases were systematically analyzed to search English-language articles published from inception to 31 December 2021. Studies were detected by using the following terms: 'obstructive sleep apnea', 'sleep quality', 'sleep disordered breathing', 'cardiac damage', 'left ventricular hypertrophy', 'systolic dysfunction', 'global longitudinal strain', 'left ventricular mechanics', 'echocardiography' and 'speckle tracking echocardiography'.

RESULTS

The meta-analysis included 889 patients with OSA and 364 non-OSA controls from 12 studies. Compared with controls, GLS was significantly reduced in the pooled OSA group (SMD -1.24 ± 0.17, CI: -1.58 to -0.90, P  < 0.0001), as well as in the normotensive OSA subgroup (SMD: -1.17 ± 0.12 CI:-1.40 to -0.95, P  < 0.0001). Similar findings were obtained in sub-analyses performed separately in mild, moderate and severe OSA. This was not the case for LV ejection fraction (LVEF) (i.e. comparisons between controls vs. mild OSA, mild vs. moderate OSA, moderate vs. severe OSA).

CONCLUSION

GLS is impaired in patients with OSA (independently from hypertension), worsening progressively from mild to moderate and severe forms, thus allowing to identify subclinical alterations of the systolic function not captured by LVEF. Therefore, myocardial strain assessment should be implemented systematically in the OSA setting to timely detect systolic dysfunction.

Obstructive sleep apnoea syndrome and left ventricular hypertrophy: a meta-analysis of echocardiographic studies

AIM

We investigated the association between obstructive sleep apnoea (OSA) and subclinical cardiac organ damage through a meta-analysis of echocardiographic studies that provided data on left ventricular hypertrophy (LVH), assessed as a categorical or continuous variable.

DESIGN

The PubMed, OVID-MEDLINE, and Cochrane library databases were systematically analyzed to search English-language articles published from 1 January 2000 to 15 August 2019. Studies were detected by using the following terms: 'obstructive sleep apnea', 'sleep quality', 'sleep disordered breathing', 'cardiac damage', 'left ventricular mass', 'left ventricular hypertrophy', and 'echocardiography'.

RESULTS

Meta-analysis included 5550 patients with OSA and 2329 non-OSA controls from 39 studies. The prevalence of LVH in the pooled OSA population was 45% (CI 35--55%). Meta-analysis of studies comparing the prevalence of LVH in participants with OSA and controls showed that OSA was associated with an increased risk of LVH (OR = 1.70, CI 1.44-2.00, P < 0.001). LV mass was significantly increased in patients with severe OSA as compared with controls (SMD 0.46 ± 0.08, CI 0.29-0.62, P < 0.001) or with mild OSA. This was not the case for studies comparing patients with unselected or predominantly mild OSA and controls (0.33 ± 0.17, CI -0.01 to 0.67, P = 0.057).

CONCLUSION

The present meta-analysis expands previous information on the relationship between OSA and echocardiographic LVH, so far based on individual studies. The overall evidence strongly suggests that the likelihood of LVH increases with the severity of OSA, thus exhibiting a continuous relationship.

Targeting subclinical organ damage in obstructive sleep apnea: a narrative review

Subclinical abnormalities in cardiac and vascular structure reflect the adverse effects triggered by a variety of risk factors on the cardiovascular (CV) system thereby representing an intermediate step in the cardiovascular continuum; such alterations are recognized as reliable markers of increased cardiovascular risk in different clinical settings including obstructive sleep apnea (OSA). The mechanisms underlying subclinical organ damage (OD) in the OSA setting are multifactorial. Hypoxemia and hypercapnia, induced by repeated collapses of upper airways, have been suggested to trigger a cascade of events such as activation of the sympathetic tone, renin-angiotensin-aldosterone system leading to endothelial dysfunction, vasoconstriction, myocardial and vascular remodeling, and hypertension. Furthermore, coexisting non-haemodynamic alterations such as increased oxidative stress, release of inflammatory substances, enhanced lipolysis and insulin resistance have been reported to play a role in the pathogenesis of both cardiac and extra-cardiac OD. In this article we reviewed available evidence on the association between OSA and subclinical cardiac (i.e., left and right ventricular hypertrophy, left atrial dilatation) and extra-cardiac organ damage (i.e., carotid atherosclerosis, arterial stiffness, microvascular retinal changes, and microalbuminuria). This association is apparently stronger for cardiac and carotid subclinical damage than for other markers (i.e., arterial stiffness and retinal changes) and mostly evident in the setting of severe OSA.

Risk of Obstructive Sleep Apnea and Echocardiographic Parameters

BACKGROUND

Obstructive sleep apnea (OSA) is a chronic progressive disorder with high mortality and morbidity rate, associated with cardiovascular diseases (CVD), especially heart failure (HF). The pathophysiological changes related to OSA can directly affect the diastolic function of the left ventricle.

OBJECTIVES

To assess the association of the risk of OSA, evaluated by the Berlin Questionnaire (BQ), and echocardiographic (ECHO) parameters related to diastolic dysfunction in individuals without HF assisted in primary care.

METHODS

A cross-sectional study that included 354 individuals (51% women) aged 45 years or older. All individuals selected were submitted to an evaluation that included the following procedures: consultation, filling out the BQ, clinical examination, laboratory examination and transthoracic Doppler echocardiography (TDE). Continuous data are presented as medians and interquartile intervals, and categoric variables in absolute and relative frequencies. The variables associated with risk of OSA and at the 0.05 level integrated the gamma regression models with a log link function. A value of p < 0.05 was considered an indicator of statistical significance. Exclusion criteria were presence of HF, to fill out the BQ and patients with hypertension and obesity not classified as high risk for OSA by other criteria. All individuals were evaluated on a single day with the following procedures: medical appointment, BQ, laboratory tests and ECHO.

RESULTS

Of the 354 individuals assessed, 63% were classified as having high risk for OSA. The patients with high risk for OSA present significantly abnormal diastolic function parameters. High risk for OSA confirmed positive and statistically significant association, after adjustments, with indicators of diastolic function, such as indexed left atrium volume LAV-i (p = 0.02); E'/A' (p < 0.01), A (p = 0.02), E/A (p < 0.01).

CONCLUSION

Our data show that patients at high risk for OSA present worsened diastolic function parameters measured by TDE.

Impact of obstructive sleep apnea on cardiac organ damage in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Both obstructive sleep apnea (OSA) and cardiac organ damage have a crucial role in acute ischemic stroke. Our aim is to explore the relationship between OSA and cardiac organ damage in acute stroke patients.

METHODS

A total of 130 consecutive patients with acute ischemic stroke were enrolled. Patients underwent full multichannel 24-h polysomnography for evaluation of OSA and echocardiography to evaluate left ventricle (LV) mass index (LV mass/BSA, LV mass/height), thickness of interventricular septum (IVS) and posterior wall (LVPW), LV ejection fraction and left atrium enlargement. Information on occurrence of arterial hypertension and its treatment before stroke was obtained from patients' history.

RESULTS

61.9% (70) of patients, mostly men (67.1%), with acute stroke had OSA (AHI > 10). Patients with acute stroke and OSA showed a significant increase (P < 0.05) of LV mass index, IVS and LVPW thickness and a significant left atrial enlargement as compared with patients without OSA. LV ejection fraction was not significantly different in stroke patients with and without OSA and was within normal limits. No relationship was found among cardiac alterations, occurrence of OSA and history of hypertension.

CONCLUSION

Acute stroke patients with OSA had higher LV mass and showed greater left atrial enlargement than patients without OSA. This study confirms the high prevalence of OSA in stroke patients, suggesting also an association between OSA and cardiac target organ damage. Our finding of structural LV abnormalities in acute stroke patients with OSA suggests a potential role of OSA as contributing factor in determining both cerebrovascular and cardiac damage, even in absence of clear link with a history of blood pressure elevation.

Obstructive sleep apnoea of mild severity: should it be treated?

PURPOSE OF REVIEW

To provide guidance in the management of mild obstructive sleep apnoea syndrome (OSAS) in the context of a very high prevalence, poor correlation with symptom profile, and lack of evidence that mild OSAS significantly contributes to comorbidity or early mortality.

RECENT FINDINGS

Mild obstructive sleep apnoea defined by hourly frequency of apnoeas or hypopnoeas (AHI) between 5 and 15 affects up to 35% of the general adult population but is much less prevalent when associated daytime symptoms are included. The poor correlation between symptoms and AHI complicates diagnosis and reports that mild OSAS is not significantly associated with comorbidity casts doubt on clinical significance. The diagnosis is complicated by night-to-night variability and by underestimation of AHI in ambulatory sleep studies that do not include sleep assessment. Active management of mild OSAS can be symptom-driven and offers a broad range of options. Lifestyle measures may be sufficient in many cases and mandibular advancement devices or positional therapy may be more effective in mild OSAS. Sleepy patients with low AHI may warrant a trial of continuous positive airway pressure therapy to establish the relationship between sleep disordered breathing and symptoms.

SUMMARY

Management of mild OSAS can focus on symptom relief to the individual patient.

Sleep-Disordered Breathing and Cardiovascular Correlates in College Football Players

This study sought to determine the cardiovascular physiologic correlates of sleep-disordered breathing (SDB) in American-style football (ASF) participants using echocardiography, vascular applanation tonometry, and peripheral arterial tonometry. Forty collegiate ASF participants were analyzed at pre- and postseason time points with echocardiography and vascular applanation tonometry. WatchPAT (inclusive of peripheral arterial tonometry) used to assess for SDB was then performed at the postseason time point. Twenty-two of 40 (55%) ASF participants demonstrated SDB with an apnea-hypopnea index (pAHI) ≥5. ASF participants with SDB were larger (109 ± 20 vs 92 ± 14 kg, p = 0.004) and more likely linemen position players (83% vs 50%, p = 0.03). Compared with those without SDB, ASF participants with SDB demonstrated relative impairments in left ventricular diastolic and vascular function as reflected by lower lateral e' (14 ± 3 vs 17 ± 3 cm/s, p = 0.007) and septal e' (11 ± 2 vs 13 ± 2 cm/s, p = 0.009) tissue velocities and higher pulse wave velocity (5.4 ± 0.9 vs 4.8 ± 0.5 m/s, p = 0.02). In the total cohort, there were significant positive correlations between pAHI and pulse wave velocity (r = 0.42, p = 0.008) and inverse correlations between pAHI and the averaged e' tissue velocities (r = -0.42, p = 0.01). In conclusion, SDB is highly prevalent in youthful collegiate ASF participants and associated with relative impairments in cardiac and vascular function. Targeted efforts to identify youthful populations with SDB, including ASF participants, and implement SDB treatment algorithms, represent important future clinical directives.

Obstructive Ventilatory Disorder in Heart Failure-Caused by the Heart or the Lung?

Heart failure (HF) is a clinical syndrome frequently associated with airway obstruction, either as a respiratory comorbidity or as a direct consequence of HF pathophysiology. Recognizing the relative contribution of an underlying airway disease as opposed to airway obstruction due to volume overload and left atrial pressure elevation is of importance for the appropriate management of patients affected by HF. This review focuses on "les liaisons dangereuses" between the heart and the lungs, outlying recent advances linking in a vicious circle of chronic obstructive lung disease (COPD) and obstructive sleep apnea (OSA) on one side and HF on the other side. It also discusses the role of pivotal diagnostic tools such as pulmonary function tests and cardiopulmonary exercise test to determine the contribution of HF and COPD to symptoms and clinical status. Treatment implications are discussed as well.

Carotid Body Ablation Abrogates Hypertension and Autonomic Alterations Induced by Intermittent Hypoxia in Rats

Chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea, enhances carotid body (CB) chemosensory responses to hypoxia and produces autonomic dysfunction, cardiac arrhythmias, and hypertension. We tested whether autonomic alterations, arrhythmogenesis, and the progression of hypertension induced by CIH depend on the enhanced CB chemosensory drive, by ablation of the CB chemoreceptors. Male Sprague-Dawley rats were exposed to control (Sham) conditions for 7 days and then to CIH (5% O2, 12/h 8 h/d) for a total of 28 days. At 21 days of CIH exposure, rats underwent bilateral CB ablation and then exposed to CIH for 7 additional days. Arterial blood pressure and ventilatory chemoreflex response to hypoxia were measured in conscious rats. In addition, cardiac autonomic imbalance, cardiac baroreflex gain, and arrhythmia score were assessed during the length of the experiments. In separate experimental series, we measured extracellular matrix remodeling content in cardiac atrial tissue and systemic oxidative stress. CIH induced hypertension, enhanced ventilatory response to hypoxia, induced autonomic imbalance toward sympathetic preponderance, reduced baroreflex gain, and increased arrhythmias and atrial fibrosis. CB ablation normalized blood pressure, reduced ventilatory response to hypoxia, and restored cardiac autonomic and baroreflex function. In addition, CB ablation reduced the number of arrhythmias, but not extracellular matrix remodeling or systemic oxidative stress, suggesting that reductions in arrhythmia incidence during CIH were related to normalization of cardiac autonomic balance. Present results show that autonomic alterations induced by CIH are critically dependent on the CB and support a main role for the CB in the CIH-induced hypertension.

Type 5 and 6 nasal septal deformities: Could we predict and prevent acute coronary syndrome attacks in the future?

Undisturbed nasal breathing is essential for normal breathing physiology as a whole. Nasal septal deformities (NSD) are well known as a factor which can remarkably and substantially affect the quality of nasal and pulmonary breathing. However, it is well known that type 5 and type 6 nasal septal deformities may cause only a moderate, unilateral nasal obstruction or none at all. The effects of nasal obstruction on the respiratory and cardiovascular systems have been well studied so far: right ventricle problems, ischemic heart diseases, sleep disorders, mucociliary clearance system disturbances, paranasal sinus pathology, have all been described as a result of impaired nasal breathing. The connection between the upper and lower respiratory systems has been recognized in allergic rhinitis and asthma as well, resulting in the united airways concept. Most recently, the ostensible connection between chronic rhinosinusitis (CRS) and acute myocardial infarction has been said to be proven. However, the results of this study might have not been well founded since there are no direct and clear proofs that CRS as a chronic inflammatory process has anything to do with the acute coronary syndrome (ACS). On the other hand, a large international study on the incidence of NSD in CRS patients, based on the Mladina classification, showed that NSD were present in a high incidence and that the most frequent deformities were types 5 (36.18%) and 7 (29.92%). The vast majority of those types 7 consisted of types 3 and (again) types 5 or types 6 (76.32%). The fact that in CRS patients a remarkably high incidence of type 5 septal deformity can be seen, gives rise to thinking that this factor perhaps plays a role in the onset of ACS. Acute coronary syndrome is one of the leading causes of death all over the world. Traditional risk factors such as family history, overweight body, smoking, stress, hypertension, hypercholesterolemia, diabetes mellitus, coronary artery calcium score, C-reactive protein, lipoprotein, homocysteine, lipoprotein-associated phospholipase A2, as well as high-density lipoprotein functionality perhaps cannot account for the entire risk for incident coronary events. Several other potential risk factors have been identified in an effort to improve risk assessment for ACS. This article reviews one of them: the possible influence of an unusual, so far unknown predisposing factor: type 5 or type 6 nasal septal deformities. They have been found as pure, isolated types or as a part of combined nasal septal deformity (type 7).