Benefit of atrial pacing in sleep apnea syndrome

[Arrhythmia in sleep apnea]

BACKGROUND

Sleep apnea is a widespread and yet still underdiagnosed condition. Various studies from the past have provided evidence that there is a link between sleep apnea and various cardiovascular diseases, including arrhythmias.

OBJECTIVE

The aim of this article is to provide an overview of the current study situation and to point out possible consequences relevant to everyday life.

MATERIAL AND METHODS

A systematic search was carried out in various databases using the keywords sleep apnea (OSAS/SA) and arrhythmias/dysrhythmias.

RESULTS

There are several pathophysiological links between sleep-related breathing disorders and cardiac arrhythmias, the most important of which appear to be intrathoracic pressure, increased adrenergic tone as well as recurrent hypoxia and hypercapnia. This results in an increased occurrence of clinically relevant arrhythmias, such as atrial fibrillation, symptomatic bradycardia, high-grade atrioventricular (AV) blocks as well as ventricular arrhythmias in patients with untreated sleep apnea. These pathologies also appear to be positively influenced by the treatment of sleep apnea.

CONCLUSION

A close correlation between sleep apnea and cardiac arrhythmias is undisputed. Large randomized studies in this respect are so far rare but it is undisputed that a thorough search should be carried out for sleep apnea and consistently treated in patients with a history of cardiac disease as this can have a relevant influence on the treatment and ultimately the prognosis of the patient.

Management of Obstructive Sleep Apnea in Patients With Heart Failure

Sleep apnea is traditionally classified as obstructive sleep apnea (OSA), which occurs when the upper airway collapses due to the relaxation of oropharyngeal musculature, and central sleep apnea occurs when the brainstem cannot stimulate breathing. Most sleep apnea in patients with heart failure (HF) results from coexisting OSA and central sleep apnea (CSA), or complex sleep apnea syndrome. OSA and CSA are common in HF and can be involved in its progression by exposure to the heart to intermittent hypoxia, increased preload and afterload, activating sympathetic, and decreased vascular endothelial function. A majority of treatments have been investigated in patients with CSA and HF; however, less or short-term randomized trials demonstrated whether treating OSA in patients with HF could improve morbidity and mortality. OSA could directly influence the patient's recovery. This review will focus on past and present studies on the various therapies for OSA in patients with HF and summarize CSA treatment options for reasons of reference and completeness. More specifically, the treatment covered include surgical and non-surgical treatments and reported the positive and negative consequences for these treatment options, highlighting possible implications for clinical practice and future research directions.

Prevalence, types and treatment of bradycardia in obstructive sleep apnea - A systematic review and meta-analysis

BACKGROUND

The association of obstructive sleep apnea (OSA) with bradycardia is not well-characterized, which may confer significant morbidity and mortality if left untreated. We sought to clarify the prevalence of comorbid OSA and bradycardia, and the effect of continuous positive airway pressure (CPAP) therapy on bradycardia outcomes.

METHODS

We systematically searched four electronic databases (PubMed, Embase, Cochrane Library, Scopus) for randomized or observational studies reporting the co-prevalence of sleep apnea and bradycardia or evaluated the use of CPAP on the incidence of bradycardias. We used random-effects models in all meta-analyses and evaluated heterogeneity using I².

RESULTS

We included 34 articles from 7204 records, comprising 4852 patients. Among patients with OSA, the pooled prevalence of daytime and nocturnal bradycardia were 25% (95% CI: 18.6 to 32.7) and 69.8% (95% CI: 41.7 to 88.2) respectively. Among patients with bradycardia, the pooled prevalence of OSA was 56.8% (95% CI: 21.5 to 86.3). CPAP treatment, compared to those without, did not significantly reduce the risk of daytime (two randomized trials; RR: 0.50; 95% CI: 0.11 to 2.21) or nocturnal bradycardia (one randomized-controlled trial and one cohort study; RR: 0.76; 95% CI: 0.48 to 1.20).

CONCLUSIONS

This meta-analysis demonstrates a high comorbid disease burden between OSA and bradycardia. Future research should explore the treatment effect of CPAP on bradycardia incidence, as compared to placebo.

Benefit of Atrial Overdrive Pacing in Patients with Sleep Apnea: A Meta-Analysis

BACKGROUND

Sleep apnea is one of the most common conditions around the world. This disorder can significantly impact cardiovascular morbidity and mortality. Atrial overdrive pacing (AOP) is a treatment modality that can potentially decrease respiratory events. There is currently a lack of evidence to confirm the benefits of AOP. We aimed to assess the impact of AOP in patients with obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed type.

METHODS

A literature search for studies that reported the impact on apnea-hypopnea index (AHI) by cardiac implantable electronic devices with different pacing modes was conducted using MEDLINE, Embase, and Cochrane Database from inception through July 2020. Pooled standard mean difference with 95%CI was calculated using a random-effects model.

RESULTS

Fifteen studies, including thirteen randomized studies and two observational studies containing 440 patients, were identified. The standard mean difference in apnea-hypopnea index of atrial overdrive pacing demonstrated less duration of apnea/hypopnea in patients with atrial overdrive pacing (AOP) (SMD -0.29, 95%CI: -0.48, -0.10, I² = 57%). Additional analysis was performed to assess the effect of atrial overdrive pacing in patients with or without severe sleep apnea syndrome (mean AHI < 30 defined as non-severe). There was no statistically significant difference in standardized mean in AHI in both subgroups between AOP and control groups (SMD -0.25, severe sleep apnea syndrome SMD -0.03, I² = 0.00%).

CONCLUSIONS

AOP was associated with a statistically significant reduction in AHI, but the magnitude of reduction was small. AOP may potentially be used as an adjunctive treatment with other modalities in treating patients with sleep apnea.

Obstructive Sleep Apnea and Pulmonary Hypertension: A Review of Literature

Obstructive sleep apnea (OSA) is a disease process involving recurrent pharyngeal collapse during sleep, resulting in apneic episodes. Clinically, symptoms can include snoring, sudden awakening with a choking-like sensation, excessive somnolence, non-restorative sleep, difficulty in starting or maintaining sleep, and fatigue. It results in impaired gas exchange, subsequently causing various cardiovascular, metabolic, and neurocognitive pathologies. Historically, OSA has been underdiagnosed and undertreated, especially in women.

OSA is associated with WHO (World Health Organization) class III pulmonary hypertension (PH) or PH due to lung disease. PH is a concerning complication of OSA and thought to occur in roughly 20% of individuals with OSA. The pathogenesis of PH in OSA can include pulmonary artery vasoconstriction and remodeling. Patients suffering from OSA who develop PH tend to have worse cardiovascular and pulmonary changes. We present a thorough review of the literature examining the interplay between OSA and PH.

Obstructive Sleep Apnea Syndrome as a Trigger of Cardiac Arrhythmias

PURPOSE OF REVIEW

Obstructive sleep apnea syndrome (OSAS) has a high prevalence in western countries. Many papers have been published with the purpose of demonstrating that OSAS acts as an arrhythmia trigger and is responsible for an increase in cardiovascular morbidity and mortality. The aim of this study was to review our knowledge on this topic.

RECENT FINDINGS

There is a lot of evidence demonstrating the relationship between OSAS and arrhythmias, but there remains a lack of an interventional randomized trial to demonstrate that by treating OSAS we can reduce arrhythmia burden. OSAS is a highly prevalent illness in western countries and is clearly related to an increase in cardiovascular mortality and morbidity. Cardiac arrhythmias are triggered by a repetitive hypoxemia, hypercapnia, acidosis, intrathoracic pressure fluctuations, reoxygenation, and arousals during apnea and hypopnea episodes. Early diagnosis and treatment of these patients can reduce further cardiovascular morbidity and mortality.

Myocardial fibrosis after COVID-19 infection and severe sinus arrest episodes in an asymptomatic patient with mild sleep apnea syndrome: A case report and review of the literature

COVID-19 infection is a new disease mainly affecting the respiratory system but is also accompanied by many extra-pulmonary manifestations. A case of a 47-year old male with unique myocardial fibrosis after COVID-19 infection involving the left ventricular wall, intraventricular septum and almost complete damage of interatrial septum, in combination with asymptomatic severe sinus arrest episodes related to mild obstructive sleep apnea syndrome is described here.

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Myocardial fibrosis may be a consequence of COVID-19 infection.

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Almost complete fibrosis of interatrial septum is a unique complication of COVID-19.

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Cardiac MRI is very useful in detecting myocardial complications.

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Severe sinus arrest episodes are very unusual in patients with mild OSA syndrome.

Benefit of buspirone on chemoreflex and central apnoeas in heart failure: a randomized controlled crossover trial

AIMS

Increased chemosensitivity to carbon dioxide (CO2 ) is an important trigger of central apnoeas (CA) in heart failure (HF), with negative impact on outcome. We hypothesized that buspirone, a 5HT1A receptor agonist that inhibits serotonergic chemoreceptor neuron firing in animals, can decrease CO2 chemosensitivity and CA in HF.

METHODS AND RESULTS

The BREATH study was a randomized, double-blind, placebo-controlled, crossover study (EudraCT-code 2015-005383-42). Outpatients with systolic HF (left ventricular ejection fraction <50%) and moderate-severe CA [nocturnal apnoea-hypopnoea index (AHI) ≥15 events/h] were randomly assigned to either oral buspirone (15 mg thrice daily) or placebo for 1 week, with a crossover design (1 week of wash-out). The primary effectiveness endpoint was a decrease in CO2 chemosensitivity >0.5 L/min/mmHg. The primary safety endpoint was freedom from serious adverse events. Sixteen patients (age 71.3 ± 5.8 years, all males, left ventricular ejection fraction 29.8 ± 7.8%) were enrolled. In the intention-to-treat analysis, more patients treated with buspirone (8/16, 50%) had a CO2 chemosensitivity reduction >0.5 L/min/mmHg from baseline than those treated with placebo (1/16, 6.7%) (difference between groups 43%, 95% confidence interval 14-73%, P = 0.016). Buspirone compared to baseline led to a 41% reduction in CO2 chemosensitivity (P = 0.001) and to a reduction in the AHI, central apnoea index and oxygen desaturation index of 42%, 79%, 77% at nighttime and 50%, 78%, 86% at daytime (all P < 0.01); no difference was observed after placebo administration (all P > 0.05). No patient reported buspirone-related serious adverse events.

CONCLUSIONS

Buspirone reduces CO2 chemosensitivity and improves CA and oxygen saturation across the 24 h in patients with HF.

Importance of cardiac implantable eletronic devices in the diagnosis of Sleep Apnea Syndrome

INTRODUCTION

Sleep Apnea Syndrome (SAS) is a prevalent respiratory disease with marked expression in the population with cardiovascular disease. The diagnosis is based on polysomnography. In patients with cardiac implantable electronic devices (CIED), the prevalence of SAS may reach 60%. The objective of this study was to evaluate the value of DEC in the SAS screening.

METHODS

Prospective study that included patients with CIED with sleep apnea algorithm. The frequency response function was activated and simplified polygraphy was performed. The data of the device were collected on the day of the polygraph.

RESULTS

The sample included 29 patients, with a mean age of 76.1 years, 71.4% of the male gender. The prevalence of SAS was 77%. For SAS, the agreement between polysomnography and the Pacemaker was Kappa = 0.54 (p = 0.001), 95% CI (0.28, 0.81) (moderate agreement); for moderate to severe SAS, the agreement was Kappa = 0.73 (p <0.001), 95% CI (0.49, 0.976) (substantial agreement). Severe SAS was obtained: sensitivity 60%, specificity 100%, positive predictive value 100%, negative predictive value 60% and diagnostic accuracy 75%; for moderate to severe SAS: sensitivity of 90%, specificity of 83%, positive predictive values of 90% and negative of 87.5%, with a diagnostic accuracy of 87.5%.

CONCLUSION

SAS is highly prevalent in patients with CIED. The values obtained through these devices have a strong positive correlation with the Apnea-Hypopnea Índex, which makes them a good tool for the screening of severe SAS.

Role of obstructive sleep apnea on the response to cardiac resynchronization therapy and all-cause mortality

BACKGROUND

The role of obstructive sleep apnea (OSA) on the response to cardiac resynchronization therapy (CRT) and all-cause mortality in patients with advanced heart failure (HF) is unknown.

OBJECTIVE

We assessed the association between OSA, response to CRT, and all-cause mortality in patients with HF.

METHODS

We analyzed records of 548 consecutive patients (mean age 65 ± 13 years; 216 (39%) women; mean follow-up period 76 ± 17 months) who received a CRT-defibrillator device from January 15, 2007 to March 30, 2016 at our tertiary care referral center.

RESULTS

A total of 180 patients (33%) had OSA. Fewer patients in the OSA group (109 [61%]) had improvement in left ventricular ejection fraction (EF) than did those in the non-OSA group (253 [69%]) (P = .001). A total of 144 patients (27%) died by the end of follow-up (OSA group: 61 [33%]; non-OSA group 83 [23%]; P < .001). OSA diagnosis was associated with a lower chance of improvement in EF (hazard ratio 0.71; 95% confidence interval 0.60-0.89) and a higher risk of all-cause mortality (hazard ratio 3.7; 95% confidence interval 2.5-6.8). This was true in continuous positive airway pressure-compliant patients and in patients with nonischemic cardiomyopathy. However, among patients with ischemic cardiomyopathy, the chance of improvement in EF and all-cause mortality was similar in patients with OSA and those without OSA.

CONCLUSION

OSA is associated with a decreased response to CRT and an increase in all-cause mortality in patients with HF. The differential effect of OSA on CRT response in patients with ischemic cardiomyopathy and nonischemic cardiomyopathy needs further study.

Management of Sleep Disordered Breathing in Patients with Heart Failure

PURPOSE OF REVIEW

This paper reviews treatment options for sleep disordered breathing (SDB) in patients with heart failure. We sought to identify therapies for SDB with the best evidence for long-term use in patients with heart failure and to minimize uncertainties in clinical practice by examining frequently discussed questions: what is the role of continuous positive airway pressure (CPAP) in patients with heart failure? Is adaptive servo-ventilation (ASV) safe in patients with heart failure? To what extent is SDB a modifiable risk factor?

RECENT FINDINGS

Consistent evidence has demonstrated that the development of SDB in patients with heart failure is a poor prognostic indicator and a risk factor for cardiovascular mortality. However, despite numerous available interventions for obstructive sleep apnea and central sleep apnea, it remains unclear what effect these therapies have on patients with heart failure. To date, all major randomized clinical trials have failed to demonstrate a survival benefit with SDB therapy and one major study investigating the use of adaptive servo-ventilation demonstrated harm. Significant questions persist regarding the management of SDB in patients with heart failure. Until appropriately powered trials identify a treatment modality that increases cardiovascular survival in patients with SDB and heart failure, a patient's heart failure management should remain the priority of medical care.

Changes in sleep patterns after vagus nerve stimulation, deep brain stimulation or epilepsy surgery: Systematic review of the literature

PURPOSE

Perform a systematic review of the literature on the effects of vagus nerve stimulation (VNS), deep brain stimulation (DBS) and epilepsy surgery in subjective and objective sleep parameters.

METHODS

We performed a literature search in the main medical databases: Medline, Embase, Cochrane, DARE and LILACS, looking for studies that evaluated the effects of VNS, DBS or epilepsy surgery on sleep parameters. In all, 36 studies, coming from 11 countries, including reviews, cohort studies, case series and case reports were included.

RESULTS

VNS induces sleep apnoea dependent of the stimulation variables. This condition can be reverted modifying these settings. Surgical procedures for epilepsy cause an improvement in objective and subjective sleep parameters that depend on the success of the procedure evaluated through ictal frequency control. There is evidence that non-pharmacologic treatment of epilepsy has different effects on sleep patterns.

CONCLUSION

It is advisable to include objective and subjective sleep parameters in the initial evaluation and follow-up of patients considered for invasive procedures for epilepsy control, especially with VNS due to the risk of sleep apnoea. More high quality studies are needed.

Obstructive sleep apnoea-hypopnoea and arrhythmias: new updates

AIMS

Obstructive sleep apnoea-hypopnoea (OSAH) is a prevalent condition characterized by repetitive pharyngeal collapse during sleep, leading to hypoxemia, hypercapnia, and persistent inspiratory efforts against an occluded airway until arousal. Several studies demonstrated that OSAH exerts acute and chronic effects on the cardiovascular system. Thus, although being a respiratory problem, the most important consequences of OSAH are cardiovascular, among which there are arrhythmias. The purpose of this review is to systematically analyse what has been recently published about the relationship between OSAH and every cardiac arrhythmia separately.

METHODS

We searched Pubmed, Scopus, Web of Science and Cochrane Collaboration databases for 'OSAHS arrhythmias', 'OSAH arrhythmias' and 'OSA arrhythmias'. We analyse 1298 articles and meta-analyses, excluding already edited reviews.

RESULTS

Arrhythmias, especially of ventricular origin, are frequent in OSAH. Ventricular premature beats, couplets and ventricular tachycardia runs are even more frequent in patients suffering from heart failure. They may be due to left heart remodelling, overwork and ischaemia and can explain at least some sudden deaths occurring between midnight and 6 a.m. Sinus pauses and atrioventricular blocks are increased according to the severity of the disturbance and may be reduced by continuous positive airway pressure therapy, preventing pace-maker implantation. Finally, atrial fibrillation, resistance against antiarrhythmic drugs and recurrences after surgical procedures are strongly related to OSAH.

CONCLUSION

Arrhythmias are frequent in OSAH. Treatment of OSAH may reduce some of them. An implantable cardioverter-defibrillator and continuous positive airway pressure should be considered in some patients.

How to take arms against central apneas in heart failure

Introduction Despite being a risk mediator in several observational studies, central apneas are currently orphan of treatment in heart failure. After the neutral effects on survival of two randomized controlled trials (RCTs) based on the use of positive airway pressure (the CANPAP and SERVE-HF trials), two alternative hypotheses have been formulated: 1) Periodic breathing/Cheyne-Stokes respiration (PB/CSR) in HF is protective. Indeed, the Naughton's hypothesis assumes that hyperventilation leads to increased cardiac output, lung volume, oxygen storage and reduced muscle sympathetic nerve activity, while central apnea to respiratory muscle rest and hypoxia-induced erythropoiesis. 2) The use of positive airway pressure is just a wrong treatment for PB/CSR. If this is the case, the search for novel potential alternative treatment approaches is mandatory in HF. Areas covered This review will focus on the crucial issue of whether PB/CSR should be treated or not in HF, first by outlining the ideal design of pathophysiological studies to test the Naughton's hypothesis and second by summarizing the treatment strategies so far proposed for PB/CSR in HF and identifying the most promising options to be tested in future RCTs. Expert commentary It is likely that PB/CSR may be compensatory in some cases, but after a certain threshold (to be defined) it becomes maladaptive with negative prognostic meaning in HF. The development of a pathophysiologically based treatment targeting feedback resetting and neurohormonal activation underlying PB/CSR is likely to be the best option to obtain survival benefits in HF.

Non-Mask-based Therapies for Central Sleep Apnea in Patients with Heart Failure

Central sleep apnea is common in heart failure and contributes to morbidity and mortality. Symptoms are often similar to those associated with heart failure and a high index of suspicion is needed. Testing is typically done in the sleep laboratory, but home testing equipment can distinguish between central and obstructive events. Treatments are limited. Mask-based therapies have been the primary treatment. Oxygen has some data but lacks long-term studies. Neurostimulation of the phrenic nerve is a new technology that has demonstrated improvement. Coordination of care between sleep specialists and cardiologists is important as the field of central sleep apnea continues to develop.

Sleep apnoea in heart failure: To treat or not to treat?

Heart failure (HF) and sleep apnoea are common disorders which frequently coexist. Two main types of apnoea occur: one is obstructive which, through recurring episodes of snoring, hypoxaemia, large negative intra-thoracic pressures and arousals from sleep leading to downstream inflammatory and autonomic nervous system changes, is thought to be a causative factor to the development of systemic hypertension and HF. The other type of apnoea, Cheyne-Stokes respiration with central sleep apnoea (CSR-CSA), is characterized by an oscillatory pattern of ventilation with a prevailing hyperventilation-induced hypocapnia, often in the absence of significant hypoxaemia and snoring, and is thought to be a consequence of advanced HF-related low cardiac output, high sympathetic nervous system activation and pulmonary congestion. CSR-CSA may be a compensatory response to advanced HF. Rostral fluid shift during sleep may play an important role in the pathogenesis of both obstructive sleep apnoea (OSA) and CSA. Studies of positive airway pressure (PAP) treatment of OSA and CSA in HF have shown short-term improvements in cardiac and autonomic function; however, there is no evidence of improved survival. Loop gain may provide useful marker of continuous PAP (CPAP) responsiveness in patients with central apnoea. A greater understanding of the pathophysiology of the interaction between obstructive and central apnoea and the various types of HF, and the mechanisms of therapies, such as PAP, is required to develop new strategies to overcome the disabling symptoms, and perhaps improve the mortality, that accompany HF with sleep apnoea.

Association of Autonomic Dysfunction and Mild Obstructive Sleep Apnea

BACKGROUND: Autonomic dysfunction (AD) has been independently associated with obstructive sleep apnea (OSA). Autonomic abnormalities are generally considered to be secondary to OSA. Autonomic dysfunction may also contribute to OSA. If AD contributes to OSA, we postulated that abnormalities may be present in mild OSA where the confounding causal effects of hypoxemia and sleep disruption are reduced.

OBJECTIVE: We evaluated autonomic function tests and sleep studies in a cohort of subjects with no known diagnosis of OSA.

METHODS: We prospectively enrolled a cohort without diagnosed OSA who were part of an ongoing study of vasomotor rhinitis (VMR) for testing. A battery of autonomic nervous system tests (sudomotor and cardiovagal), nonattended polysomnography, and three-site esophageal/pharyngeal pH monitoring were performed.

RESULTS: Twenty of 22 patients completed the test battery and 12 (60%) met criteria for OSA (Apnea/Hypopnea Index “AHI” >5 events/hour). AHI correlated to mean tilt table blood pressure decrease (R = 0.58, P = 0.007) and the Valsalva-mediated phase 2 mean blood pressure decrease (R = 0.52, P = 0.017). OSA severity was related to sympathetic but not parasympathetic abnormalities. No differences in blood pressure responses were related to age, oxygen desaturation nadir, gastroesophageal reflux, VMR, or sleepiness.

CONCLUSION: Autonomic abnormalities suggestive of decreased adrenergic tone are associated with mild OSA. These abnormalities may potentially be secondary but may also precede development of OSA. (Otolaryngol Head Neck Surg 2004;130: 643-8.)

Management of Noncardiac Comorbidities in Chronic Heart Failure

Prevalence of heart failure is increasing, especially in the elderly population. Noncardiac comorbidities complicate heart failure care and are increasingly common in elderly patients with reduced or preserved ejection fraction heart failure, owing to prolongation of patient's lives by advances in chronic heart failure (CHF) management. Common comorbidities include respiratory disease, renal dysfunction, anemia, arthritis, obesity, diabetes mellitus, cognitive dysfunction, and depression. These conditions contribute to the progression of the disease and may alter the response to treatment, partly as polypharmacy is inevitable in these patients. Cardiologists and other physicians caring for patients with CHF need to be vigilant to comorbid conditions that complicate the care of these patients. There is now more guidance on management of noncardiac comorbidities in heart failure, and this article contains a comprehensive review of the most recent updates on management of noncardiac comorbidities in CHF.

Heart failure and sleep disorders

Awareness of the importance of sleep-related disorders in patients with cardiovascular diseases is growing. In particular, sleep-disordered breathing, short sleep time, and low sleep quality are frequently reported by patients with heart failure (HF). Sleep-disordered breathing, which includes obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), is common in patients with HF and has been suggested to increase the morbidity and mortality in these patients. Both OSA and CSA are associated with increased sympathetic activation, vagal withdrawal, altered haemodynamic loading conditions, and hypoxaemia. Moreover, OSA is strongly associated with arterial hypertension, the most common risk factor for cardiac hypertrophy and failure. Intrathoracic pressure changes are also associated with OSA, contributing to haemodynamic alterations and potentially affecting overexpression of genes involved in ventricular remodelling. HF treatment can decrease the severity of both OSA and CSA. Indeed, furosemide and spironolactone administration, exercise training, cardiac resynchronization therapy, and eventually heart transplantation have shown a positive effect on OSA and CSA in patients with HF. At present, whether CSA should be treated and, if so, which is the optimal therapy is still debated. By contrast, more evidence is available on the beneficial effects of OSA treatment in patients with HF.

Effect of cardiac pacing on sleep-related breathing disorders: a systematic review

Sleep-related breathing disorders are commonly encountered in the middle-aged population, negatively affecting quality of life. Central sleep apnea is associated with congestive heart failure, whereas obstructive sleep apnea is related to different pathophysiologic mechanisms, such as the total or partial occlusion of upper airway tract. Both sleep-related disorders have been associated with increased morbidity, and hence, they have been a target of several treatment strategies. The aim of this systematic review is to evaluate the effect of different types of cardiac pacing on sleep-related breathing disorders in patients with or without heart failure. The PubMed and Cochrane Central Register of Controlled Trials were examined from April 2015 to January 2016. Of the initial 360 studies, 22 eligible trials were analyzed. The included studies were classified according to the type of sleep disorder and the intervention undertaken. The evidence shows that cardiac resynchronization therapy but not atrial overdrive pacing can reduce apneic events in central sleep apnea patients. However, their effect on obstructive sleep apnea is controversial. It can be assumed that pacing cannot be used alone as treatment of sleep-related breathing disorders. Further research is needed in order to elucidate the effect of these interventions in sleep apnea patients.

Haddad Syndrome

Congenital central hypoventilation syndrome (CCHS) causes predominantly sleep apnoea and is one of a growing number of inherited disorders characterised by autonomic nervous system dysfunction/dysregulation (ANSD). In association with Hirschsprung's disease (HSCR), it presents as Haddad's syndrome. We report a case of Haddad's syndrome complicated by sinus node dysfunction.

An 18-Year-Old Woman With Snoring and Refractory Epilepsy

An 18-year-old woman with a history of refractory complex partial epilepsy presented for evaluation of snoring and episodes of gasping for air during sleep. She had uncontrolled epilepsy since the age of 8 years despite trial of multiple antiepileptic medications. She eventually underwent an implantation of a vagus nerve stimulator (VNS) device (model 103; Cyberonics Inc) with gradual adjustment of the VNS settings for better seizure control.

Respiratory sleep disorders in patients with congestive heart failure

Respiratory sleep disorders (RSD) occur in about 40-50% of patients with symptomatic congestive heart failure (CHF). Obstructive sleep apnea (OSA) is considered a cause of CHF, whereas central sleep apnea (CSA) is considered a response to heart failure, perhaps even compensatory. In the setting of heart failure, continuous positive airway pressure (CPAP) has a definite role in treating OSA with improvements in cardiac parameters expected. However in CSA, CPAP is an adjunctive therapy to other standard therapies directed towards the heart failure (pharmacological, device and surgical options). Whether adaptive servo controlled ventilatory support, a variant of CPAP, is beneficial is yet to be proven. Supplemental oxygen therapy should be used with caution in heart failure, in particular, by avoiding hyperoxia as indicated by SpO2 values >95%.

Increased Vagal Tone and Sleep Apnea Syndrome

It has been observed that atrial overdrive pacing abolishes sleep apnea syndrome, but how it does so has not been explained. There is a possibility that it sends a retrograde inhibitory impulse to the vagal center in the brainstem, which in turn reduces the vagal tone, and thus prevents sleep apnea. Therefore, medical vagolytics such as atropine type of drugs should have the same effect. This is a case report of such an attempt.

Mechanisms and clinical consequences of untreated central sleep apnea in heart failure

Central sleep apnea (CSA) is a highly prevalent, though often unrecognized, comorbidity in patients with heart failure (HF). Data from HF population studies suggest that it may present in 30% to 50% of HF patients. CSA is recognized as an important contributor to the progression of HF and to HF-related morbidity and mortality. Over the past 2 decades, an expanding body of research has begun to shed light on the pathophysiologic mechanisms of CSA. Armed with this growing knowledge base, the sleep, respiratory, and cardiovascular research communities have been working to identify ways to treat CSA in HF with the ultimate goal of improving patient quality of life and clinical outcomes. In this paper, we examine the current state of knowledge about the mechanisms of CSA in HF and review emerging therapies for this disorder.

Arrhythmia risk associated with sleep disordered breathing in chronic heart failure

The intersecting relationships of sleep disordered breathing (SDB), arrhythmogenic risk and chronic heart failure (HF) are complex and most likely multi-directional and synergistic. Autonomic dysfunction is a common pathophysiological feature of each of these entities. Intermittent hypoxia, hypercapnia, mechanical cardiac influences due to upper airway obstruction and rostral fluid shifts are SDB-specific mechanisms which may trigger, perpetuate and exacerbate HF and arrhythmogenesis. Specific pathophysiological mechanisms will vary according to the predominance of central as compared to obstructive sleep apnea. The risk of cardiac arrhythmias and HF attributable to SDB may be considerable given the high prevalence of SDB and its likely physiologic burden. The current review focuses on the data, which have accrued elucidating the specific contributory mechanisms of SDB in cardiac arrhythmias and HF, highlighting the clinical relevance and effects of standard SDB treatment on these outcomes, and describing the role of novel therapeutics.

Cardiac or Other Implantable Electronic Devices and Sleep-disordered Breathing - Implications for Diagnosis and Therapy

Sleep-disordered breathing (SDB) is of growing interest in cardiology because SDB is a highly prevalent comorbidity in patients with a variety of cardiovascular diseases. The prevalence of SDB is particularly high in patients with cardiac dysrhythmias and/or heart failure. In this setting, many patients now have implantable cardiac devices, such as pacemakers, implantable cardioverter-defibrillators or implanted cardiac resynchronisation therapy devices (CRT). Treatment of SDB using implantable cardiac devices has been studied previously, with atrial pacing and CRT being shown not to bring about satisfactory results in SDB care. The latest generations of these devices have the capacity to determine transthoracic impedance, to detect and quantify breathing efforts and to identify SDB. The capability of implantable cardiac devices to detect SDB is of potential importance for patients with cardiovascular disease, allowing screening for SDB, monitoring of the course of SDB in relation to cardiac status, and documenting of the effects of treatment.

Sleep-disordered breathing increases the risk of arrhythmias

Sleep-disordered breathing (SDB) has been consistently associated with increased risk for cardiovascular diseases, including arrhythmias. The purpose of this review is to elucidate the several pathophysiologic pathways such as repetitive hypoxia and reoxygenation, increased oxidative stress, inflammation and sympathetic activation that may underlie the increased incidence of arrhythmias in SDB patients. We discuss in particular the incidence of ventricular arrhythmias, atrial fibrillation and bradyarrhythmias in SDB patients. In addition, we discuss the electrocardiographic alteration such as ST-T changes during apneic events and QT dispersion induced by SDB that may trigger complex ventricular arrhythmias and sudden cardiac death. Finally, we consider also the therapeutic interventions such as continuous positive airways pressure therapy, a standard treatment for SDB, that may reduce the incidence and recurrence of supraventricular and ventricular arrhythmias in patients with SDB.

The association of sleep disordered breathing with heart failure and other cardiovascular conditions

An abundance of evidence exists in support of primary and secondary prevention for tackling the scourge of cardiovascular disease. Despite our wealth of knowledge, certain deficiencies still remain. One such example is the association between sleep disordered breathing (SDB) and cardiovascular disease. A clear body of evidence exists to link these two disease entities (independent of other factors such as obesity and smoking), yet our awareness of this association and its clinical implication does not match that of other established cardiovascular risk factors. Here, we outline the available evidence linking SDB and cardiovascular disease as well as discussing the potential consequences and management in the cardiovascular disease population.

Central sleep apnea

Neurophysiologically, central apnea is due to a temporary failure in the pontomedullary pacemaker generating breathing rhythm. As a polysomnographic finding, central apneas occur in many pathophysiological conditions. Depending on the cause or mechanism, central apneas may not be clinically significant, for example, those that occur normally at sleep onset. In contrast, central apneas occur in a number of disorders and result in pathophysiological consequences. Central apneas occur commonly in high-altitude sojourn, disrupt sleep, and cause desaturation. Central sleep apnea also occurs in number of disorders across all age groups and both genders. Common causes of central sleep apnea in adults are congestive heart failure and chronic use of opioids to treat pain. Under such circumstances, diagnosis and treatment of central sleep apnea may improve quality of life, morbidity, and perhaps mortality. The mechanisms of central sleep apnea have been best studied in congestive heart failure and hypoxic conditions when there is increased CO2 sensitivity below eupnea resulting in lowering eupneic PCO2 below apneic threshold causing cessation of breathing until the PCO2 rises above the apneic threshold when breathing resumes. In many other disorders, the mechanism of central sleep apnea (CSA) remains to be investigated.

Sleep-disordered breathing in patients undergoing transfemoral aortic valve implantation for severe aortic stenosis

BACKGROUND

We examined the prevalence of sleep-disordered breathing (SDB) in patients with severe aortic valve stenosis (AS) and the impact of transfemoral aortic valve implantation (TAVI) on SDB.

METHODS

79 patients underwent cardiorespiratory polygraphy (PG) before TAVI (CoreValve™), 62 of them a second PG after the procedure.

RESULTS

Forty-nine (62 %) patients had obstructive sleep apnea (OSA), 25 (32 %) central sleep apnea (CSA), and 5 (6 %) presented without significant SDB (apnea-hypopnea index (AHI) < 5/h). Among the 62 patients evaluated before and after TAVI, 36 (58 %) had OSA, 22 (36 %) CSA, and 4 patients (7 %) no SDB. AHI was significantly higher in CSA patients than in OSA patients (34.5 ± 18.3 vs. 18.0 ± 12.6/h, p < 0.001). Successful TAVI had a significant impact on CSA but not on OSA: CSA patients with optimal TAVI results experienced a significant reduction in central respiratory events (AHI 39.6 ± 19.6-23.1 ± 16.0/h, p = 0.035), while no changes were detected in OSA patients (AHI 18.8 ± 13.0-20.25 ± 13.4/h, p = 0.376). In contrast, in patients who developed at least moderate periprosthetic aortic regurgitation (AR > I), CSA increased significantly (AHI 26.3 ± 13.2-39.2 ± 18.4/h, p = 0.036), whereas no acute change was seen in patients with OSA (AHI 10.5 ± 7.8-12.5 ± 5.0/h, p = 0.5).

CONCLUSION

OSA and CSA are prevalent in more than 90 % of patients undergoing TAVI for severe aortic valve stenosis. Successful TAVI had no significant impact on OSA but improved CSA. In case of an acute change from pressure overload (aortic stenosis) to acute volume overload (aortic regurgitation after TAVI), central, but not obstructive, sleep apnea deteriorated.

Sleep-disordered breathing in patients with heart failure: new trends in therapy

Heart failure (HF) is a growing health problem which paradoxically results from the advances in the treatment of etiologically related diseases (especially coronary artery disease). HF is commonly accompanied by sleep-disordered breathing (SDB), which may directly exacerbate the clinical manifestations of cardiovascular disease and confers a poorer prognosis. Obstructive sleep apnoea predominates in mild forms while central sleep apnoea in more severe forms of heart failure. Identification of SDB in patients with HF is important, as its effective treatment may result in notable clinical benefits to the patients. Continuous positive airway pressure (CPAP) is the gold standard in the management of SDB. The treatments for central breathing disorders include CPAP, bilevel positive airway pressure (BPAP), and adaptive servoventilation (ASV), with the latter being the most modern method of treatment for the Cheyne-Stokes respiration and involving ventilation support with a variable synchronisation dependent on changes in airflow through the respiratory tract and on the patient's respiratory rate. ASV exerts the most favourable effect on long-term prognosis. In this paper, we review the current state of knowledge on the diagnosis and treatment of SDB with a particular emphasis on the latest methods of treatment.

[Sleep apnea and heart failure]

Sleep apnea can influence cardiac function, by which the development of heart failure is facilitated. Vice versa, chronic heart failure increases the risk for sleep apnea. Consequently, in patients with symptomatic chronic heart failure, sleep apnea is a frequent comorbidity occuring in up to 75% of cases. More than half of those suffer from central sleep apnea, whereas in the general population, obstructive sleep apnea is far more frequent. Both, the obstructive and the central sleep apnea lead to oxygen desaturations during the night which are followed by increases in serum catecholamines. Possibly, this is the main mechanism why the prognosis of patients with symptomatic heart failure and sleep apnea is much worse than that of patients without sleep apnea. Therefore, a screening of all heart failure patients for sleep apnea is mandatory. Currently, large studies are underway which investigate whether the treatment of sleep apnea, esp. central sleep apnea, will beneficially influence the clinical course of heart failure (SERVE-HF, ADVENT-HF). A new therapeutic approach for central sleep apnea is the phrenic nerve stimulation.

A case of positional central sleep apnea

Obstructive sleep apnea results from structural compromise of the upper airway and decreased muscle tone during sleep. Central sleep apnea is usually due to instability of the feedback mechanism of the body that controls respiration. While positional changes commonly affect the severity of obstructive sleep apnea, the effect of positional changes on the severity of central sleep apnea is less well known.

The association between atrial fibrillation and stroke in patients with obstructive sleep apnea: a population-based case-control study

BACKGROUND

Obstructive sleep apnea (OSA) has been shown to be an independent risk factor for ischemic stroke and may increase the risk of atrial fibrillation (AF) by up to fourfold. Given these relationships, it is possible that OSA may provide a link between stroke and AF. A case-control study was conducted to examine the association between AF and stroke in patients with OSA.

METHODS

Olmsted County, MN, USA, residents with a new diagnosis of OSA based on polysomnography (PSG) between 2005 and 2010 (N = 2980) who suffered a first-time ischemic stroke during the same period were identified as cases. Controls with no history of stroke were randomly chosen from the same database. Univariate and multiple logistic regression analyses were performed with age, gender, body mass index (BMI), smoking, hypertension, hyperlipidemia, diabetes mellitus, apnea-hypopnea index (AHI) and coronary artery disease (CAD) as co-variates, with the diagnosis of AF as the variable of interest.

RESULTS

A total of 108 subjects were studied. Mean age of cases (n = 34) was 73 ± 12 years and 53% were men. Among controls (n = 74), mean age was 61 ± 16 years and 55% were male. On univariate analyses, AF was significantly more common in the cases than among controls (50.0% vs 10.8%, p < 0.01). On multivariate regression analyses, the association between AF and stroke was significant after controlling for age, BMI, coronary artery disease, hypertension, diabetes mellitus, hyperlipidemia and smoking status (corrected odds ratio (OR): 5.34; 95% confidence interval (CI): 1.79-17.29).

CONCLUSIONS

Patients with OSA who had a stroke had higher rates of AF even after accounting for potential confounders.