Shift in sleep apnoea type in heart failure patients in the CANPAP trial

Central Apneas Are More Detrimental in Female Than in Male Patients With Heart Failure

Background

Central apneas (CA) are a frequent comorbidity in patients with heart failure (HF) and are associated with worse prognosis. The clinical and prognostic relevance of CA in each sex is unknown.

Methods and Results

Consecutive outpatients with HF with either reduced or mildly reduced left ventricular ejection fraction (n=550, age 65±12 years, left ventricular ejection fraction 32%±9%, 21% women) underwent a 24‐hour ambulatory polygraphy to evaluate CA burden and were followed up for the composite end point of cardiac death, appropriate implantable cardioverter‐defibrillator shock, or first HF hospitalization. Compared with men, women were younger, had higher left ventricular ejection fraction, had lower prevalence of ischemic etiology and of atrial fibrillation, and showed lower apnea‐hypopnea index (expressed as median [interquartile range]) at daytime (3 [0–9] versus 10 [3–20] events/hour) and nighttime (10 [3–21] versus 23 [11–36] events/hour) (all P<0.001), despite similar neurohormonal activation and HF therapy. Increased chemoreflex sensitivity to either hypoxia or hypercapnia (evaluated in 356 patients, 65%, by a rebreathing test) was less frequent in women (P<0.001), but chemoreflex sensitivity to hypercapnia was a predictor of apnea‐hypopnea index in both sexes. At adjusted survival analysis, daytime apnea‐hypopnea index ≥15 events/hour (hazard ratio [HR], 2.70; 95% CI, 1.06–7.34; P=0.037), nighttime apnea‐hypopnea index ≥15 events/hour (HR, 2.84; 95% CI, 1.28–6.32; P=0.010), and nighttime CA index ≥10 events/hour (HR, 5.01; 95% CI, 1.88–13.4; P=0.001) were independent predictors of the primary end point in women but not in men (all P>0.05), also after matching women and men for possible confounders.

Conclusions

In chronic HF, CA are associated with a greater risk of adverse events in women than in men.

Elevated serum matrix metalloproteinase-2 levels in heart failure patients with reduced ejection fraction and Cheyne-Stokes respiration

STUDY OBJECTIVES

Cheyne-Stokes respiration (CSR), a kind of central sleep apnea (CSA), is referred to as a poor prognostic factor in heart failure patients with reduced ejection fraction (HFrEF). Matrix metalloproteinase (MMP) and B-type natriuretic peptide (BNP) play important roles in HFrEF patients and are markers of poor prognosis. However, there is no literature mentioning the changes in MMP and BNP in HFrEF patients with CSR.

METHODS

From June 2018 to June 2019, 41 adult patients with stable heart failure and left ventricular ejection fraction (LVEF) <50% were enrolled from the cardiology clinic. After history taking and medication review to exclude possible central nervous system or medication related CSA, an overnight polysomnography study was performed, and CSR was identified. The morning serum MMP-2, MMP-9 and BNP levels were determined using enzyme-linked immunosorbent assay and fluorescence immunoassay techniques. A positive airway pressure (PAP) device was applied to 7 patients for 3 months.

RESULTS

The serum MMP-2 and BNP levels were significantly higher in HFrEF patients with CSR than in patients without CSR. In addition, elevated serum MMP-2 levels correlated well with the severity of sleep apnea and intermittent hypoxia, which were represented as the apnea-hypopnea index and the oxygen-desaturation index. No positive correlation was found between those markers and LVEF. Finally, the treatment of sleep apnea with CPAP for 3 months tended to reduce the elevated serum MMP-2 levels.

CONCLUSIONS

Higher serum MMP-2 and BNP levels were found in HFrEF patients with CSR. Elevated MMP-2 levels were correlated with the severity of sleep apnea and intermittent hypoxia.

Sleep Apnoea and Heart Failure

Heart Failure (HF) and Sleep-Disordered-Breathing (SDB) are two common conditions that frequently overlap and have been studied extensively in the past three decades. Obstructive Sleep Apnea (OSA) may result in myocardial damage, due to intermittent hypoxia increased sympathetic activity and transmural pressures, low-grade vascular inflammation and oxidative stress. On the other hand, central sleep apnoea and Cheyne-Stokes respiration (CSA-CSR) occurs in HF, irrespective of ejection fraction either reduced (HFrEF), preserved (HFpEF) or mildly reduced (HFmrEF). The pathophysiology of CSA-CSR relies on several mechanisms leading to hyperventilation, breathing cessation and periodic breathing. Pharyngeal collapse may result at least in part from fluid accumulation in the neck, owing to daytime fluid retention and overnight rostral fluid shift from the legs. Although both OSA and CSA-CSR occur in HF, the symptoms are less suggestive than in typical (non-HF related) OSA. Overnight monitoring is mandatory for a proper diagnosis, with accurate measurement and scoring of central and obstructive events, since the management will be different depending on whether the sleep apnea in HF is predominantly OSA or CSA-CSR. SDB in HF are associated with worse prognosis, including higher mortality than in patients with HF but without SDB. However, there is currently no evidence that treating SDB improves clinically important outcomes in patients with HF, such as cardiovascular morbidity and mortality.

A prospective five-year cohort study of undiagnosed sleep apnea in patients undergoing coronary artery bypass graft surgery

BACKGROUND

We aimed to study prospectively the nature and effect of sleep apnea-hypopnea syndrome (SAHS) in patients undergoing coronary artery bypass graft (CABG) surgery over five years of follow-up.

METHODS

Patients undergoing CABG surgery (N.=145) were assessed longitudinally (baseline, 1 year, and 5 years post-surgery) using the 'STOP-BANG' screen of sleep apnea risk. Additionally, all patients had a preoperative multiple-channel sleep-study, providing acceptable data for an obstructive and central apnea, and desaturation index in 97 patients.

RESULTS

Preoperatively, over half (63%) of patients obtained an apnea-hypopnea index score (combining apnea types) in the moderate-severe range for SAHS, and STOP-BANG threshold score (>3/8) was reached by most (95%) patients. Despite some improvement in 'STOP symptoms' at 1-year follow-up, most patients (98%) remained at risk of SAHS at 5 years post-surgery. There was an underlying and chronic relationship between STOP-BANG score and cardiac symptoms at both baseline and 5-year follow-up. Additionally, SAHS variables were associated with greater incidence of acute postoperative events, and generally with increased length of stay on the intensive care unit.

CONCLUSIONS

We confirm that SAHS is common in CABG-surgery patients, presenting additional clinical challenges and cost implications. The underlying pathophysiology is complex, including upper airway obstruction and cardiorespiratory changes of heart failure. In patients presenting for CABG-surgery, we show chronic susceptibility to SAHS, likely associated with traditional risk factors e.g. obesity but perhaps also with gradual decline in heart function itself. Superimposed on this, there is potential for exacerbated risk of morbidity at the time of CABG surgery itself.

Central and Obstructive Apneas in Heart Failure With Reduced, Mid-Range and Preserved Ejection Fraction

Background: Although central apneas (CA) and obstructive apneas (OA) are highly prevalent in heart failure (HF), a comparison of apnea prevalence, predictors and clinical correlates in the whole HF spectrum, including HF with reduced ejection fraction (HFrEF), mid-range EF (HFmrEF) and preserved EF (HFpEF) has never been carried out so far.

Materials and methods: 700 HF patients were prospectively enrolled and then divided according to left ventricular EF (408 HFrEF, 117 HFmrEF, 175 HFpEF). All patients underwent a thorough evaluation including: 2D echocardiography; 24-h Holter-ECG monitoring; cardiopulmonary exercise testing; neuro-hormonal assessment and 24-h cardiorespiratory monitoring.

Results: In the whole population, prevalence of normal breathing (NB), CA and OA at daytime was 40, 51, and 9%, respectively, while at nighttime 15, 55, and 30%, respectively. When stratified according to left ventricular EF, CA prevalence decreased (daytime: 57 vs. 43 vs. 42%, p = 0.001; nighttime: 66 vs. 48 vs. 34%, p < 0.0001) from HFrEF to HFmrEF and HFpEF, while OA prevalence increased (daytime: 5 vs. 8 vs. 18%, p < 0.0001; nighttime 20 vs. 29 vs. 53%, p < 0.0001).

In HFrEF, male gender and body mass index (BMI) were independent predictors of both CA and OA at nighttime, while age, New York Heart Association functional class and diastolic dysfunction of daytime CA. In HFmrEF and HFpEF male gender and systolic pulmonary artery pressure were independent predictors of CA at daytime, while hypertension predicted nighttime OA in HFpEF patients; no predictor of nighttime CA was identified. When compared to patients with NB, those with CA had higher neuro-hormonal activation in all HF subgroups. Moreover, in the HFrEF subgroup, patients with CA were older, more comorbid and with greater hemodynamic impairment while, in the HFmrEF and HFpEF subgroups, they had higher left atrial volumes and more severe diastolic dysfunction, respectively. When compared to patients with NB, those with OA were older and more comorbid independently from background EF.

Conclusions: Across the whole spectrum of HF, CA prevalence increases and OA decreases as left ventricular systolic dysfunction progresses. Different predictors and specific clinical characteristics might help to identify patients at risk of developing CA or OA in different HF phenotypes.

Treatment of central sleep apnea in patients with heart failure: Now and future

Heart failure (HF) is known to be associated with sleep-disordered breathing (SDB). In addition to disturbing patients’ sleep, SDB is also associated with a deterioration in the cardiac function and an increased mortality and morbidity. Central sleep apnea (CSA), typically characterized by Cheyne-Stokes breathing (CSB), is increasingly found in patients with HF compared to the general population. An important pathogenetic factor of CSA seen in HF patients is an instability in the control of the respiratory system, characterized by both hypocapnia and increased chemosensitivity. Sympathetic overactivation, pulmonary congestion and increased chemosensitivity associated with HF stimulate the pulmonary vagal irritant receptor, resulting in chronic hyperventilation and hypocapnia. Additionally, the repetitive apnea and arousal cycles induce cyclic sympathetic activation, which may worsen the cardiac prognosis. Correcting CSB may improve both patient’s quality of life and HF syndrome itself. However, a treatment for HF in patients also experiencing CSA is yet to be found. In fact, conflicting results from numerous clinical studies investigating sleep apnea with HF guide to a troubling question, that is whether (or not) sleep apnea should be treated in patients with HF? This editorial attempts to both collect the current evidence about randomized control trials investigating CSA in patients with HF and highlight the effect of specific CSA treatments on cardiovascular endpoints.

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.

Epidemiology of Sleep-Disordered Breathing and Heart Failure: What Drives What

PURPOSE OF REVIEW

The bidirectional relationships that have been demonstrated between heart failure (HF) and central sleep apnea (CSA) demand further exploration with respect to the implications that each condition has for the other. This review discusses the body of literature that has accumulated on these relationships and how CSA and its potential treatment may affect outcomes in patients with CSA.

RECENT FINDINGS

Obstructive sleep apnea (OSA) can exacerbate hypertension, type 2 diabetes, obesity, and atherosclerosis, which are known predicates of HF. Conversely, patients with HF more frequently exhibit OSA partly due to respiratory control system instability. These same mechanisms are responsible for the frequent association of HF with CSA with or without a Hunter-Cheyne-Stokes breathing (HCSB) pattern. Just as is the case with OSA, patients with HF complicated by CSA exhibit more severe cardiac dysfunction leading to increased mortality; the increase in severity of HF can in turn worsen the degree of sleep disordered breathing (SDB). Thus, a bidirectional relationship exists between HF and both phenotypes of SDB; moreover, an individual patient may exhibit a combination of these phenotypes. Both types of SDB remain significantly underdiagnosed in patients with HF and hence undertreated. Appropriate screening for, and treatment of, OSA is clearly a significant factor in the comprehensive management of HF, while the relevance of CSA remains controversial. Given the unexpected results of the Treatment of Sleep-Disordered Breathing with Predominant Central Sleep Apnea by Adaptive Servo Ventilation in Patients with Heart Failure trial, it is now of paramount importance that additional analysis of these data be expeditiously reported. It is also critical that ongoing and proposed prospective studies of this issue proceed without delay.

Phenotyping of Sleep-Disordered Breathing in Patients With Chronic Heart Failure With Reduced Ejection Fraction-the SchlaHF Registry

BACKGROUND

Different sleep-disordered breathing (SDB) phenotypes, including coexisting obstructive and central sleep apnea (OSA-CSA), have not yet been characterized in a large sample of patients with heart failure and reduced ejection fraction (HFrEF) receiving guideline-based therapies. Therefore, the aim of the present study was to determine the proportion of OSA, CSA, and OSA-CSA, as well as periodic breathing, in HFrEF patients with SDB.

METHODS AND RESULTS

The German SchlaHF registry enrolled patients with HFrEF receiving guideline-based therapies, who underwent portable SDB monitoring. Polysomnography (n=2365) was performed in patients with suspected SDB. Type of SDB (OSA, CSA, or OSA-CSA), the occurrence of periodic breathing (proportion of Cheyne-Stokes respiration ≥20%), and blood gases were determined in 1557 HFrEF patients with confirmed SDB. OSA, OSA-CSA, and CSA were found in 29%, 40%, and 31% of patients, respectively; 41% showed periodic breathing. Characteristics differed significantly among SDB groups and in those with versus without periodic breathing. There was a relationship between greater proportions of CSA and the presence of periodic breathing. Risk factors for having CSA rather than OSA were male sex, older age, presence of atrial fibrillation, lower ejection fraction, and lower awake carbon dioxide pressure (pco2). Periodic breathing was more likely in men, patients with atrial fibrillation, older patients, and as left ventricular ejection fraction and awake pco2 decreased, and less likely as body mass index increased and minimum oxygen saturation decreased.

CONCLUSIONS

SchlaHF data show that there is wide interindividual variability in the SDB phenotype of HFrEF patients, suggesting that individualized management is appropriate.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT01500759.

Design of the effect of adaptive servo-ventilation on survival and cardiovascular hospital admissions in patients with heart failure and sleep apnoea: the ADVENT-HF trial

INTRODUCTION

Both types of sleep-disordered breathing (SDB), obstructive and central sleep apnoea (OSA and CSA, respectively), are common in patients with heart failure and reduced ejection fraction (HFrEF). In such patients, SDB is associated with increased cardiovascular morbidity and mortality but it remains uncertain whether treating SDB by adaptive servo-ventilation (ASV) in such patients reduces morbidity and mortality.

AIM

ADVENT-HF is designed to assess the effects of treating SDB with ASV on morbidity and mortality in patients with HFrEF.

METHODS

ADVENT-HF is a multicentre, multinational, randomized, parallel-group, open-label trial with blinded assessment of endpoints of standard medical therapy for HFrEF alone vs. with the addition of ASV in patients with HFrEF and SDB. Patients with a history of HFrEF undergo echocardiography and polysomnography. Those with a left ventricular ejection fraction ≤45% and SDB (apnoea-hypopnoea index ≥15) are eligible. SDB is stratified into OSA with ≥50% of events obstructive or CSA with >50% of events central. Those with OSA must not have excessive daytime sleepiness (Epworth score of ≤10). Patients are then randomized to receive or not receive ASV. The primary outcome is the composite of all-cause mortality, cardiovascular hospital admissions, new-onset atrial fibrillation requiring anti-coagulation but not hospitalization, and delivery of an appropriate discharge from an implantable cardioverter-defibrillator not resulting in hospitalization during a maximum follow-up time of 5 years.

CONCLUSION

The ADVENT-HF trial will help to determine whether treating SDB by ASV in patients with HFrEF improves morbidity and mortality.

Trajectories of Emergent Central Sleep Apnea During CPAP Therapy

BACKGROUND

The emergence of central sleep apnea (CSA) during positive airway pressure (PAP) therapy has been observed clinically in approximately 10% of obstructive sleep apnea titration studies. This study assessed a PAP database to investigate trajectories of treatment-emergent CSA during continuous PAP (CPAP) therapy.

METHODS

U.S. telemonitoring device data were analyzed for the presence/absence of emergent CSA at baseline (week 1) and week 13. Defined groups were as follows: obstructive sleep apnea (average central apnea index [CAI] < 5/h in week 1, < 5/h in week 13); transient CSA (CAI ≥ 5/h in week 1, < 5/h in week 13); persistent CSA (CAI ≥ 5/h in week 1, ≥ 5/h in week 13); emergent CSA (CAI < 5/h in week 1, ≥ 5/h in week 13).

RESULTS

Patients (133,006) used CPAP for ≥ 90 days and had ≥ 1 day with use of ≥ 1 h in week 1 and week 13. The proportion of patients with CSA in week 1 or week 13 was 3.5%; of these, CSA was transient, persistent, or emergent in 55.1%, 25.2%, and 19.7%, respectively. Patients with vs without treatment-emergent CSA were older, had higher residual apnea-hypopnea index and CAI at week 13, and more leaks (all P < .001). Patients with any treatment-emergent CSA were at higher risk of therapy termination vs those who did not develop CSA (all P < .001).

CONCLUSIONS

Our study identified a variety of CSA trajectories during CPAP therapy, identifying several different clinical phenotypes. Identification of treatment-emergent CSA by telemonitoring could facilitate early intervention to reduce the risk of therapy discontinuation and shift to more efficient ventilator modalities.

Prognostic Significance of Central Apneas Throughout a 24-Hour Period in Patients With Heart Failure

BACKGROUND

Large trials using noninvasive mechanical ventilation to treat central apnea (CA) occurring at night ("sleep apnea") in patients with systolic heart failure (HF) have failed to improve prognosis. The prevalence and prognostic value of CA during daytime and over an entire 24-h period are not well described.

OBJECTIVES

This study evaluated the occurrence and prognostic significance of nighttime, daytime, and 24-h CA episodes in a large cohort of patients with systolic HF.

METHODS

Consecutive patients receiving guideline-recommended treatment for HF (n = 525; left ventricular ejection fraction [LVEF] of 33 ± 9%; 66 ± 12 years of age; 77% males) underwent prospective evaluation, including 24-h respiratory recording, and were followed-up using cardiac mortality as an endpoint.

RESULTS

The 24-h prevalence of predominant CAs (apnea/hypopnea index [AHI] ≥5 events/h, with CA of >50%) was 64.8% (nighttime: 69.1%; daytime: 57.0%), whereas the prevalence of predominant obstructive apneas (OA) was 12.8% (AHI ≥5 events/h with OAs >50%; nighttime: 14.7%; daytime: 5.9%). Episodes of CA were associated with neurohormonal activation, ventricular arrhythmic burden, and systolic/diastolic dysfunction (all p < 0.05). During a median 34-month follow-up (interquartile range [IQR]: 17 to 36 months), 50 cardiac deaths occurred. Nighttime, daytime, and 24-h moderate-to-severe CAs were associated with increased cardiac mortality (AHI of </≥15 events/h; log-rank: 6.6, 8.7, and 5.3, respectively; all p < 0.05; central apnea index [CAI] of </≥10 events/h; log-rank 8.9, 11.2, and 10.9, respectively; all p < 0.001). Age, B-type natriuretic peptide level, renal dysfunction, 24-h AHI, CAI, and time with oxygen saturation of <90% were independent predictors of outcome.

CONCLUSIONS

In systolic HF patients, CAs occurred throughout a 24-h period and were associated with a neurohormonal activation, ventricular arrhythmic burden, and worse prognosis.

Change in type of sleep-disordered breathing from predominant central to obstructive sleep apnea following coronary artery bypass grafting

We report the case of a 67-year-old overweight man with reduced left ventricular ejection fraction (LVEF) due to myocardial infarction. He had an implantable cardioverter defibrillator (ICD) for frequent episodes of ventricular tachyarrhythmia and was initiated into adaptive-servo ventilation therapy for severe central sleep apnea (CSA), which was not suppressed by continuous positive airway pressure (CPAP). Since he still had several episodes of appropriate ICD therapies, coronary angiogram was performed, and severe three-vessel disease was found. He then underwent coronary artery bypass grafting (CABG). After CABG, his LVEF did not improve (from 29 to 25%); however, the B-type natriuretic peptide level decreased (from 560 to 330 pg/mL). Although the apnea-hypopnea index did not change (49.4 before and 55.1/h after CABG), his CSA converted to predominant obstructive sleep apnea accompanied by a shortening of the lung-to-finger circulation time (from 43 to 29 s) 2 weeks after CABG, which was completely suppressed by CPAP. <Learning objective: Central sleep apnea (CSA) can be alleviated by treatments for heart failure. However, limited data are available regarding resolution of CSA after coronary revascularization. We describe a case whose predominant CSA converted to obstructive sleep apnea after surgical coronary revascularization without any improvements in systolic function. Coronary revascularization can alleviate CSA possibly through altering congestive status and may unmask obstructive phenotype in patients with severe coronary artery disease.>.

Novel Therapies for the Treatment of Central Sleep Apnea

Neurophysiologically, central apnea is due to a temporary cessation of respiratory rhythmogenesis in medullary respiratory networks. Central apneas occur in several disorders and result in pathophysiological consequences, including arousals and desaturation. The 2 most common causes 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 mortality. This article discusses recent developments in the treatment of central sleep apnea in heart failure and opioids use.

Management of Sleep Apnea Syndromes in Heart Failure

Central sleep apnea (CSA) and obstructive sleep apnea (OSA) are prevalent in heart failure (HF) and associated with a worse prognosis. Nocturnal oxygen therapy may decrease CSA events, sympathetic tone, and improve left ventricular ejection fraction, although mortality benefit is unknown. Although treatment of OSA in patients with HF is recommended, therapy for CSA remains controversial. Continuous positive airway pressure use in HF-CSA may improve respiratory events, hemodynamics, and exercise capacity, but not mortality. Adaptive servo ventilation is contraindicated in patients with symptomatic HF with predominant central sleep-disordered events. The role of phrenic nerve stimulation in CSA therapy is promising.

Pathogenesis of central and complex sleep apnoea

Central sleep apnoea (CSA) - the temporary absence or diminution of ventilatory effort during sleep - is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, that is elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas. Indeed, treatment of OSA, whether via continuous positive airway pressure (CPAP), tracheostomy or oral appliances, can reveal CSA, an occurrence referred to as complex sleep apnoea. Factors influencing loop gain include increased chemosensitivity (increased controller gain), reduced damping of blood gas levels (increased plant gain) and increased lung to chemoreceptor circulatory delay. Sleep-wake transitions and pharyngeal dilator muscle responses effectively raise the controller gain and therefore also contribute to total loop gain and overall instability. In some circumstances, for example apnoea of infancy and central congenital hypoventilation syndrome, central apnoeas are the consequence of ventilatory depression and defective ventilatory responses, that is low loop gain. The efficacy of available treatments for CSA can be explained in terms of their effects on loop gain, for example CPAP improves lung volume (plant gain), stimulants reduce the alveolar-inspired PCO₂ difference and supplemental oxygen lowers chemosensitivity. Understanding the magnitude of loop gain and the mechanisms contributing to instability may facilitate personalized interventions for CSA.

Significance of obstructive sleep apnea in the patient with pulmonary hypertension

PURPOSE OF REVIEW

The purpose of this review was to evaluate the consequence of obstructive sleep apnea (OSA) in pulmonary hypertension by reviewing the current literature and understanding potential pathophysiological mechanisms.

RECENT FINDINGS

Small studies have suggested a high prevalence of comorbid OSA in those with known pulmonary hypertension. Pathophysiological mechanisms are highly suggestive of potential deleterious effect of OSA on pulmonary hemodynamics.

SUMMARY

Clearly, current research work on comorbid OSA and pulmonary hypertension is still in its infancy and the field is ripe for future investigation. The significance of OSA in this population has yet to be fully determined.

Effect of ultrafiltration on sleep apnea and sleep structure in patients with end-stage renal disease

RATIONALE

In end-stage renal disease (ESRD), a condition characterized by fluid overload, both obstructive and central sleep apnea (OSA and CSA) are common. This observation suggests that fluid overload is involved in the pathogenesis of OSA and CSA in this condition.

OBJECTIVES

To test the hypothesis that fluid removal by ultrafiltration (UF) will reduce severity of OSA and CSA in patients with ESRD.

METHODS

At baseline, on a nondialysis day, patients with ESRD on thrice-weekly hemodialysis underwent overnight polysomnography along with measurement of total body extracellular fluid volume (ECFV), and ECFV of the neck, thorax, and right leg before and after sleep. The following week, on a nondialysis day, subjects with an apnea-hypopnea index (AHI) greater than or equal to 20 had fluid removed by UF, followed by repeat overnight polysomnography with fluid measurements.

MEASUREMENTS AND MAIN RESULTS

Fifteen patients (10 men) with an AHI greater than or equal to 20 (10 OSA; 5 CSA) participated. Mean age was 53.5 ± 10.4 years and mean body mass index was 25.3 ± 4.8 kg/m(2). Following removal of 2.17 ± 0.45 L by UF, the AHI decreased by 36% (43.8 ± 20.3 to 28.0 ± 17.7; P < 0.001) without affecting uremia. The reduction in AHI correlated with the reduction in total body ECFV (r = 0.567; P = 0.027) and was associated with reductions in ECFV of the right leg (P = 0.001), overnight change in ECFV of the right leg (P = 0.044), ECFV of the thorax (P = 0.001), and ECFV of the neck (P = 0.003).

CONCLUSIONS

These findings indicate that fluid overload contributes to the pathogenesis of OSA and CSA in ESRD, and that fluid removal by UF attenuates sleep apnea without altering uremic status.

Sleep and breathing in congestive heart failure

Heart failure (HF) is one of the most prevalent and costly diseases in the United States. Sleep apnea is now recognized as a common, yet underdiagnosed, comorbidity of HF. This article discusses the unique qualities that sleep apnea has when it occurs in HF and explains the underlying pathophysiology that illuminates why sleep apnea and HF frequently occur together. The authors provide an overview of the treatment options for sleep apnea in HF and discuss the relative efficacies of these treatments.

Clinical predictors of sleep apnoea in heart failure outpatients

BACKGROUND

Sleep-disordered breathing (SDB) is common in heart failure patients. Many of them still remain undiagnosed. The aim of this study was to detect clinical predictors of sleep apnoea which may help to identify patients with SDB at a heart failure clinic.

METHODS

We performed an in-home sleep study on 115 consecutive patients from our heart failure clinic. Clinical characteristics, blood samples, daytime sleepiness and quality of life were registered.

RESULTS

Among 115 patients, 52% had moderate to severe SDB. Body Mass Index (BMI) ≥ 30 kg/m² was the only independent predictor of moderate to severe SDB [Odds ratio (OR) = 3.62, 95% Confidence interval (CI) 1.40-9.36, p = 0.008]. Quality of life and level of sleepiness were not significantly associated with SDB. Patients with mild to moderate chronic obstructive pulmonary disease (COPD) were unlikely to have SDB compared with patients without COPD (OR = 0.10, 95% CI 0.02-0.43, p = 0.002). Hypertension was a predictor of having obstructive sleep apnoea (OR = 2.78, 95% CI 1.15-6.75, p = 0.02), while haemoglobin ≥ 15 g/dl was associated with central sleep apnoea (OR = 6.71, 95% CI 1.96-22.99, p = 0.002).

CONCLUSION

BMI ≥ 30 kg/m(2) is associated with moderate to severe SDB, both obstructive and central sleep apnoea. Thus, BMI may be used as one of the selection criteria for referral of heart failure patients to a sleep specialist.

Elimination of central sleep apnea by cardiac valve replacement: a continuous follow-up study in patients with rheumatic valvular heart disease

BACKGROUND

Recent studies have suggested that cardiac surgery may affect sleep-disordered breathing (SDB) in chronic heart failure patients. However, the dynamic changes in sleep apnea and heart function after cardiac surgery and the mechanisms responsible for these changes remain unknown.

METHODS

Patients with rheumatic valvular heart disease (RVHD) and SDB were enrolled and followed up at three, six and 12 months after cardiac valve replacement (CVR). Baseline and follow-up clinical data consisting of NYHA classification, 6min walk distance (6-MWD), medications, echocardiography, electrocardiography, chest X-ray, arterial blood gas, lung-to-finger circulation time (LFCT), and sleep data were collected and evaluated.

RESULTS

Twenty-four central sleep apnea (CSA) patients and 15 obstructive sleep apnea (OSA) patients completed three follow-up assessments. Comparison of the baseline parameters between OSA patients and CSA patients showed that CSA patients had a worse baseline cardiac function assessed by higher NYHA class, shorter 6-MWD, larger left atrial diameter, longer LFCT, and enhanced chemosensitivity (higher pH and lower arterial carbon dioxide tension (PaCO2)). A continuous significant elevation in 6-MWD and left ventricular ejection fraction and decrease in NYHA class, plasma BNP, and left atrial diameter were found in both CSA and OSA patients. When comparing CSA and OSA patients, the CSA indices were remarkably reduced at month 3 post CVR and sustained throughout the trial, whereas there were no significant decreases in OSA index and hypopnea index. pH values and LFCT were markedly decreased and PaCO2 markedly increased in patients with CSA at the end of the third months following CVR. These changes were sustained until the end of the trial.

CONCLUSIONS

CSA patients with RVHD had a worse baseline cardiac function, enhanced chemosensitivity and disordered hemodynamic as compared with OSA patients with RVHD. CSA were eliminated after CVR; however, there were no changes in OSA. The elimination of CSA, post CVR, is associated with the combined efficacies of improvement of cardiac function, normalized chemosensitivity, and stabilized hemodynamic.

Impact of predischarge nocturnal pulse oximetry (sleep-disordered breathing) on postdischarge clinical outcomes in hospitalized patients with left ventricular systolic dysfunction after acute decompensated heart failure

Stratifying patients at a high risk for readmission and mortality before their discharge after acute decompensated heart failure (ADHF) is important. Although sleep-disordered breathing (SDB) is prevalent in patients with chronic heart failure, only few studies have investigated the impact of SDB on hospitalized patients with left ventricular (LV) systolic dysfunction after ADHF. Thus, we assessed the prevalence of SDB using nocturnal pulse oximetry and the relation between SDB and clinical events in this patient group. One hundred consecutive patients with LV systolic dysfunction who were hospitalized for ADHF were enrolled in the study. Predischarge nocturnal oximetry was performed to determine if they had SDB (defined as an oxygen desaturation index of ≥5 events/hour with ≥4% decrease in saturation level). Data on death and readmission for ADHF were collected. Forty-one patients had SDB. Complete outcome data were collected in the mean follow-up period of 14.2 months during which 33 events occurred. On multivariate Cox proportional hazards regression analysis, the presence of SDB was a significant independent predictor of postdischarge readmission and mortality (hazard ratio 2.93, p = 0.006). In conclusion, SDB, as determined by predischarge nocturnal oximetry, is prevalent and is an independent predictor of the combined end point of readmission and mortality in hospitalized patients with LV systolic dysfunction after ADHF.

Sleep-disordered breathing in patients with heart failure

Sleep-disordered breathing (SDB) is prevalent in patients with heart failure, and is associated with increased morbidity and mortality. SDB is proinflammatory, with nocturnal oxygen desaturations and hypercapnia appearing to play a pivotal role in the development of oxidative stress and sympathetic activation. Preliminary data suggest that attention to the diagnosis and management of SDB in patients with heart failure may improve outcomes. Ongoing research into the roles of comorbidities such as SDB as a treatment target may lead to better clinical outcomes and improved quality of life for patients with heart failure.

Prevalence and risk factors of sleep disordered breathing in patients with rheumatic valvular heart disease

STUDY OBJECTIVES

Sleep disordered breathing (SDB) is common in patients with chronic heart failure secondary to non-valvular heart disease; however, the prevalence and characteristics of SDB in patients with rheumatic valvular heart disease (RVHD) are unclear. This study was designed to determine the prevalence, characteristics, and risk factors for SDB in RVHD patients.

METHODS

A cross-sectional study was conducted in 260 RVHD patients. The following data were recorded: types of heart valve lesions, electrocardiographic, echocardiographic, arterial blood gas analysis findings, baseline medication, 6-minute walk test (6MWT) distance, and sleep parameters.

RESULTS

Compared to patients with single leftsided valve lesions, patients with left- and rightsided valve lesions had a higher prevalence of SDB (46.2% vs. 31.2%, p = 0.013); the increased prevalence of SDB only involved central sleep apnea (CSA) (31.1% vs. 14.1%, p = 0.001). Patients with obstructive sleep apnea (OSA) or CSA were older and had a shorter 6MWT distance, lower left ventricle ejection fraction and PaO₂, a longer lung-to-finger circulation time, and a higher prevalence of atrial fibrillation (AF) and hypertension (all p < 0.05) as compared with patients without SDB. Multinomial logistic regression analysis showed that PaO2 ≤ 85 mm Hg was the only risk factor for OSA. Male gender, AF, 6MWT distance ≤ 300 m, PaO₂ ≤ 85 mmHg, and PaCO₂ ≤ 40 mm Hg were risk factors for CSA.

CONCLUSIONS

Patients with RVHD had a high prevalence of SDB (predominantly CSA). RVHD patients with SDB, particularly those who had CSA, manifested more severe symptoms and greater impairment of cardiac function. Assessments of clinical manifestations of cardiac dysfunction may be important for predicting the risk factors for SDB.

Contrasting effects of lower body positive pressure on upper airways resistance and partial pressure of carbon dioxide in men with heart failure and obstructive or central sleep apnea

OBJECTIVES

This study sought to test the effects of rostral fluid displacement from the legs on transpharyngeal resistance (Rph), minute volume of ventilation (Vmin), and partial pressure of carbon dioxide (PCO2) in men with heart failure (HF) and either obstructive (OSA) or central sleep apnea (CSA).

BACKGROUND

Overnight rostral fluid shift relates to severity of OSA and CSA in men with HF. Rostral fluid displacement may facilitate OSA if it shifts into the neck and increases Rph, because pharyngeal obstruction causes OSA. Rostral fluid displacement may also facilitate CSA if it shifts into the lungs and induces reflex augmentation of ventilation and reduces PCO2, because a decrease in PCO2 below the apnea threshold causes CSA.

METHODS

Men with HF were divided into those with mainly OSA (obstructive-dominant, n = 18) and those with mainly CSA (central-dominant, n = 10). While patients were supine, antishock trousers were deflated (control) or inflated for 15 min (lower body positive pressure [LBPP]) in random order.

RESULTS

LBPP reduced leg fluid volume and increased neck circumference in both obstructive- and central-dominant groups. However, in contrast to the obstructive-dominant group in whom LBPP induced an increase in Rph, a decrease in Vmin, and an increase in PCO2, in the central-dominant group, LBPP induced a reduction in Rph, an increase in Vmin, and a reduction in PCO2.

CONCLUSIONS

These findings suggest mechanisms by which rostral fluid shift contributes to the pathogenesis of OSA and CSA in men with HF. Rostral fluid shift could facilitate OSA if it induces pharyngeal obstruction, but could also facilitate CSA if it augments ventilation and lowers PCO2.

Rules for scoring respiratory events in sleep: update of the 2007 AASM Manual for the Scoring of Sleep and Associated Events. Deliberations of the Sleep Apnea Definitions Task Force of the American Academy of Sleep Medicine

The American Academy of Sleep Medicine (AASM) Sleep Apnea Definitions Task Force reviewed the current rules for scoring respiratory events in the 2007 AASM Manual for the Scoring and Sleep and Associated Events to determine if revision was indicated. The goals of the task force were (1) to clarify and simplify the current scoring rules, (2) to review evidence for new monitoring technologies relevant to the scoring rules, and (3) to strive for greater concordance between adult and pediatric rules. The task force reviewed the evidence cited by the AASM systematic review of the reliability and validity of scoring respiratory events published in 2007 and relevant studies that have appeared in the literature since that publication. Given the limitations of the published evidence, a consensus process was used to formulate the majority of the task force recommendations concerning revisions.The task force made recommendations concerning recommended and alternative sensors for the detection of apnea and hypopnea to be used during diagnostic and positive airway pressure (PAP) titration polysomnography. An alternative sensor is used if the recommended sensor fails or the signal is inaccurate. The PAP device flow signal is the recommended sensor for the detection of apnea, hypopnea, and respiratory effort related arousals (RERAs) during PAP titration studies. Appropriate filter settings for recording (display) of the nasal pressure signal to facilitate visualization of inspiratory flattening are also specified. The respiratory inductance plethysmography (RIP) signals to be used as alternative sensors for apnea and hypopnea detection are specified. The task force reached consensus on use of the same sensors for adult and pediatric patients except for the following: (1) the end-tidal PCO(2) signal can be used as an alternative sensor for apnea detection in children only, and (2) polyvinylidene fluoride (PVDF) belts can be used to monitor respiratory effort (thoracoabdominal belts) and as an alternative sensor for detection of apnea and hypopnea (PVDFsum) only in adults.The task force recommends the following changes to the 2007 respiratory scoring rules. Apnea in adults is scored when there is a drop in the peak signal excursion by ≥ 90% of pre-event baseline using an oronasal thermal sensor (diagnostic study), PAP device flow (titration study), or an alternative apnea sensor, for ≥ 10 seconds. Hypopnea in adults is scored when the peak signal excursions drop by ≥ 30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative sensor, for ≥ 10 seconds in association with either ≥ 3% arterial oxygen desaturation or an arousal. Scoring a hypopnea as either obstructive or central is now listed as optional, and the recommended scoring rules are presented. In children an apnea is scored when peak signal excursions drop by ≥ 90% of pre-event baseline using an oronasal thermal sensor (diagnostic study), PAP device flow (titration study), or an alternative sensor; and the event meets duration and respiratory effort criteria for an obstructive, mixed, or central apnea. A central apnea is scored in children when the event meets criteria for an apnea, there is an absence of inspiratory effort throughout the event, and at least one of the following is met: (1) the event is ≥ 20 seconds in duration, (2) the event is associated with an arousal or ≥ 3% oxygen desaturation, (3) (infants under 1 year of age only) the event is associated with a decrease in heart rate to less than 50 beats per minute for at least 5 seconds or less than 60 beats per minute for 15 seconds. A hypopnea is scored in children when the peak signal excursions drop is ≥ 30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative sensor, for ≥ the duration of 2 breaths in association with either ≥ 3% oxygen desaturation or an arousal. In children and adults, surrogates of the arterial PCO(2) are the end-tidal PCO(2) or transcutaneous PCO(2) (diagnostic study) or transcutaneous PCO(2) (titration study). For adults, sleep hypoventilation is scored when the arterial PCO(2) (or surrogate) is > 55 mm Hg for ≥ 10 minutes or there is an increase in the arterial PCO(2) (or surrogate) ≥ 10 mm Hg (in comparison to an awake supine value) to a value exceeding 50 mm Hg for ≥ 10 minutes. For pediatric patients hypoventilation is scored when the arterial PCO(2) (or surrogate) is > 50 mm Hg for > 25% of total sleep time. In adults Cheyne-Stokes breathing is scored when both of the following are met: (1) there are episodes of ≥ 3 consecutive central apneas and/or central hypopneas separated by a crescendo and decrescendo change in breathing amplitude with a cycle length of at least 40 seconds (typically 45 to 90 seconds), and (2) there are five or more central apneas and/or central hypopneas per hour associated with the crescendo/decrescendo breathing pattern recorded over a minimum of 2 hours of monitoring.

Association of smoking, sleep apnea, and plasma alkalosis with nocturnal ventricular arrhythmias in men with systolic heart failure

BACKGROUND

Excess sudden death due to ventricular tachyarrhythmias remains a major mode of mortality in patients with systolic heart failure. The aim of this study was to determine the association of nocturnal ventricular arrhythmias in patients with low ejection fraction heart failure. We incorporated a large number of known pathophysiologic triggers to identify potential targets for therapy to reduce the persistently high incidence of sudden death in this population despite contemporary treatment.

METHODS

Eighty-six ambulatory male patients with stable low (≤ 45%) ejection fraction heart failure underwent full-night attendant polysomnography and simultaneous Holter recordings. Patients were divided into groups according to the presence or absence of couplets (paired premature ventricular excitations) and ventricular tachycardia (VT) (at least three consecutive premature ventricular excitations) during sleep.

RESULTS

In multiple regression analysis, four variables (current smoking status, increased number of arousals, plasma alkalinity, and old age) were associated with VT and two variables (apnea-hypopnea index and low right ventricular ejection fraction) were associated with couplets during sleep.

CONCLUSIONS

We speculate that cessation of smoking, effective treatment of sleep apnea, and plasma alkalosis could collectively decrease the incidence of nocturnal ventricular tachyarrhythmias and the consequent risk of sudden death, which remains high despite the use of β blockades.

Conversion from predominant central sleep apnea to obstructive sleep apnea following valvuloplasty in a patient with mitral regurgitation

A few reports have shown that cardiac valve repair may improve central sleep apnea (CSA) in patients with valvular heart disease. It has been suggested that such improvements are associated with the improvement of cardiac function. We report the case of a 67-year-old man with mitral regurgitation, whose CSA converted to predominant obstructive sleep apnea following mitral valvuloplasty in association with a shortening of lung-to-finger circulation time.

Adaptive servoventilation improves cardiac function and respiratory stability

Cheyne–Stokes respiration (CSR) in patients with chronic heart failure (CHF) is of major prognostic impact and expresses respiratory instability. Other parameters are daytime pCO₂, VE/VCO₂-slope during exercise, exertional oscillatory ventilation (EOV), and increased sensitivity of central CO₂ receptors. Adaptive servoventilation (ASV) was introduced to specifically treat CSR in CHF. Aim of this study was to investigate ASV effects on CSR, cardiac function, and respiratory stability. A total of 105 patients with CHF (NYHA ≥ II, left ventricular ejection fraction (EF) ≤ 40%) and CSR (apnoea–hypopnoea index ≥ 15/h) met inclusion criteria. According to adherence to ASV treatment (follow-up of 6.7 ± 3.2 months) this group was divided into controls (rejection of ASV treatment or usage <50% of nights possible and/or <4 h/night; n = 59) and ASV (n = 56) adhered patients. In the ASV group, ventilator therapy was able to effectively treat CSR. In contrast to controls, NYHA class, EF, oxygen uptake, 6-min walking distance, and NT-proBNP improved significantly. Moreover, exclusively in these patients pCO₂, VE/VCO₂-slope during exercise, EOV, and central CO₂ receptor sensitivity improved. In CHF patients with CSR, ASV might be able to improve parameters of SDB, cardiac function, and respiratory stability.

Nocturnal rostral fluid shift: a unifying concept for the pathogenesis of obstructive and central sleep apnea in men with heart failure

BACKGROUND

Obstructive sleep apnea (OSA) and central sleep apnea are common in patients with heart failure. We hypothesized that in such patients, severity of OSA is related to overnight rostral leg fluid displacement and increase in neck circumference, severity of central sleep apnea is related to overnight rostral fluid displacement and to sleep Pco(2), and continuous positive airway pressure alleviates OSA in association with prevention of fluid accumulation in the neck.

METHODS AND RESULTS

In 57 patients with heart failure (ejection fraction <or=45%), we measured change in leg fluid volume and neck circumference before and after polysomnography, and we measured transcutaneous Pco(2) during polysomnography. Patients were divided into an obstructive-dominant group (>or=50% of apneas and hypopneas obstructive) and a central-dominant group (>50% of events central). Patients with OSA received continuous positive airway pressure. In obstructive-dominant patients, there were inverse relationships between overnight change in leg fluid volume and both the overnight change in neck circumference (r=-0.780, P<0.001) and the apnea-hypopnea index (r=-0.881, P<0.001) but not transcutaneous Pco(2). In central-dominant patients, the overnight reduction in leg fluid volume correlated inversely with the apnea-hypopnea index (r=-0.919, P<0.001) and the overnight change in neck circumference (r=-0.568, P=0.013) and directly with transcutaneous Pco(2) (r=0.569, P=0.009). Continuous positive airway pressure alleviated OSA in association with prevention of the overnight increase in neck circumference (P<0.001).

CONCLUSIONS

Our findings suggest that nocturnal rostral fluid shift is a unifying concept contributing to the pathogenesis of both OSA and central sleep apnea in patients with heart failure.