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

Rostral ventrolateral medullary catecholaminergic neurones mediate irregular breathing pattern in volume overload heart failure rats

KEY POINTS

A strong association between disordered breathing patterns, elevated sympathetic activity, and enhanced central chemoreflex drive has been shown in experimental and human heart failure (HF). The aim of this study was to determine the contribution of catecholaminergic rostral ventrolateral medulla catecholaminergic neurones (RVLM-C1) to both haemodynamic and respiratory alterations in HF. Apnoea/hypopnoea incidence (AHI), breathing variability, respiratory-cardiovascular coupling, cardiac autonomic control and cardiac function were analysed in HF rats with or without selective ablation of RVLM-C1 neurones. Partial lesion (∼65%) of RVLM-C1 neurones reduces AHI, respiratory variability, and respiratory-cardiovascular coupling in HF rats. In addition, the deleterious effects of central chemoreflex activation on cardiac autonomic balance and cardiac function in HF rats was abolished by ablation of RVLM-C1 neurones. Our findings suggest that RVLM-C1 neurones play a pivotal role in breathing irregularities in volume overload HF, and mediate the sympathetic responses induced by acute central chemoreflex activation.

ABSTRACT

Rostral ventrolateral medulla catecholaminergic neurones (RVLM-C1) modulate sympathetic outflow and breathing under normal conditions. Heart failure (HF) is characterized by chronic RVLM-C1 activation, increased sympathetic activity and irregular breathing patterns. Despite studies showing a relationship between RVLM-C1 and sympathetic activity in HF, no studies have addressed a potential contribution of RVLM-C1 neurones to irregular breathing in this context. Thus, the aim of this study was to determine the contribution of RVLM-C1 neurones to irregular breathing patterns in HF. Sprague-Dawley rats underwent surgery to induce volume overload HF. Anti-dopamine β-hydroxylase-saporin toxin (DβH-SAP) was used to selectively lesion RVLM-C1 neurones. At 8 weeks post-HF induction, breathing pattern, blood pressures (BP), respiratory-cardiovascular coupling (RCC), central chemoreflex function, cardiac autonomic control and cardiac function were studied. Reduction (∼65%) of RVLM-C1 neurones resulted in attenuation of irregular breathing, decreased apnoea-hypopnoea incidence (11.1 ± 2.9 vs. 6.5 ± 2.5 events h-1 ; HF+Veh vs. HF+DβH-SAP; P < 0.05) and improved cardiac autonomic control in HF rats. Pathological RCC was observed in HF rats (peak coherence >0.5 between breathing and cardiovascular signals) and was attenuated by DβH-SAP treatment (coherence: 0.74 ± 0.12 vs. 0.54 ± 0.10, HF+Veh vs. HF+DβH-SAP rats; P < 0.05). Central chemoreflex activation had deleterious effects on cardiac function and cardiac autonomic control in HF rats that were abolished by lesion of RVLM-C1 neurones. Our findings reveal that RVLM-C1 neurones play a major role in irregular breathing patterns observed in volume overload HF and highlight their contribution to cardiac dysautonomia and deterioration of cardiac function during chemoreflex activation.

Comparison of Stanford B Aortic Dissection Patients Who Received Thoracic Endovascular Aortic Repair Combined with or without Sleep Apnea Syndrome

BACKGROUND

Patients with Stanford B aortic dissection (AD) are usually found to have sleep apnea syndrome (SAS). This condition always complicates the patients' respiration. In this study, we collected and analyzed data of patients' perioperative managements during thoracic endovascular aortic repair (TEVAR) for treating patients with Stanford B AD and SAS. Comparison has been made between the patients with SAS and those without SAS.

METHODS

Between June 2013 and June 2014, the clinical data and outcomes of the Stanford B AD patients in the Department of Vascular Surgery in the Second Xiangya Hospital were retrospectively reviewed and studied. According to the result of polysomnography obtained by using a portable polysomnography monitor (Nox T3, Nox Medical Co. Iceland) in TEVAR candidates, patients have been stratified into SAS-positive and SAS-negative group. Comparison of various variables has been made between these 2 groups.

RESULTS

One hundred thirty-four patients, with Stanford B AD and treated by TEVAR in our center, were enrolled in this study. Patients' mean age was 52.46 ± 10.84 years. Gender ratio is 114:20, including male 85.07% (114/134) and female 14.93% (20/134). TEVAR was performed in 71.64% (96/134) patients under general anesthesia and 38 patients under local anesthesia. The mean body mass index (BMI) was 23.5 ± 4.2, and the longest follow-up time was 46 months. The patients were stratified into SAS-positive group (n = 23) and SAS-negative group (n = 111). Compared with the patients in the SAS-negative group, those in the SAS-positive group were younger (54.36 ± 0.97 vs. 43.3 ± 1.84 P < 0.0001) but had higher BMI (25.48 ± 0.71 vs. 22.24 ± 0.23, P < 0.0001), with longer hospitalization time (25.52 ± 0.59 vs. 15.68 ± 0.27; P < 0.0001) and without significant differences in the intensive care unit (ICU) stay time (54.87 ± 12.57 vs. 40.27 ± 8.10; P = 0.3369). Furthermore, the complication rate of pulmonary infection (65.22% vs. 13.51%; P < 0.0001), respiratory failure (26.09% vs. 1.80%; P = 0.003), heart failure (26.09% vs. 3.60%; P = 0.0018), and renal failure (30.43% vs. 5.40%; P = 0.0016) are significantly different between SAS-positive and SAS-negative groups. According to the 46-month follow-up, the survival rate of the 2 groups had no significant differences (P = 0.0846). The SAS-negative group result showed that the survival time had no significant correlation with all the factors we explored, whereas the SAS-positive group result showed that the survival time is significantly correlated only with pulmonary infection/failure (r = 0.2798, 95% confidence interval 0.08741 to 0.452, P = 0.0038).

CONCLUSIONS

Stanford B AD patients who had SAS are likely to have higher BMI. After treating with TEVAR, they usually have longer hospitalization and ICU stay time, as well as higher complication rate. However, there are no significant differences of the survival rate in midtime follow-up. The respiratory system evaluation should be considered carefully in those patients who have diagnosed as having SAS before and after TEVAR because those patients' survival situation may have correlation with their respiratory condition.

Sleep-disordered breathing in heart failure: The state of the art after the SERVE-HF trial

Heart failure (HF) is one of the most prevalent conditions worldwide and despite therapeutic advances, its prognosis remains poor. Among the multiple comorbidities in HF, sleep-disordered breathing (SDB) is frequent and worsens the prognosis. Preliminary observational studies suggested that treatment of SDB could modify the prognosis of HF, and the issue has gained importance in recent years. The diagnosis of SDB is expensive, slow and suboptimal, and there is thus a need for screening devices that are easier to use and validated in this population. The first-line treatment involves optimization of medical therapy for heart failure. Continuous positive airway pressure (CPAP) is used in patients who mainly suffer from obstructive sleep apnea. In patients with predominantly central sleep apnea, CPAP is not sufficient and adaptive servo-ventilation (ASV), despite promising results in observational studies, showed no benefit in patients with symptomatic HF and reduced ejection fraction in the SERVE-HF randomized trial; on the contrary, there was unexpectedly increased mortality in the ASV group compared to controls, and so ASV is contraindicated in these patients, calling into question the definition and pathogenesis of SDB and risk stratification in these patients. There are many gaps in the evidence, and so further research is needed to better understand this issue: definitions, simple screening methods, and whether and how to treat SDB in patients with HF.

Cheyne-Stokes respiration during sleep: mechanisms and potential interventions

Cheyne-Stokes respiration is characterized by a typical waxing and waning pattern in breathing amplitude, interspersed with central apnoeas or hypopnoeas. This article reviews current knowledge regarding Cheyne-Stokes respiration with a particular emphasis on the mechanisms and latest methods of intervention.

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.