Sleep-Disordered Breathing and Cardiac Arrhythmias

Interactions of Obstructive Sleep Apnea With the Pathophysiology of Cardiovascular Disease, Part 1: JACC State-of-the-Art Review

The American Heart Association considers sleep health an essential component of cardiovascular health, and sleep is generally a time of cardiovascular quiescence, such that any deviation from normal sleep may be associated with adverse cardiovascular consequences. Many studies have shown that both impaired quantity and quality of sleep, particularly with obstructive sleep apnea (OSA) and comorbid sleep disorders, are associated with incident cardiometabolic consequences. OSA is associated with repetitive episodes of altered blood gases, arousals, large negative swings in intrathoracic pressures, and increased sympathetic activity. Recent studies show that OSA is also associated with altered gut microbiota, which could contribute to increased risk of cardiovascular disease. OSA has been associated with hypertension, atrial fibrillation, heart failure, coronary artery disease, stroke, and excess cardiovascular mortality. Association of OSA with chronic obstructive lung disease (overlap syndrome) and morbid obesity (obesity hypoventilation syndrome) increases the odds of mortality.

Sleep apnea and sudden death in the non-cardiac population: A systematic review

INTRODUCTION

Obstructive sleep apnea (OSA) is one of the main risk factors for cardiovascular diseases and is associated with both morbidity and mortality. OSA has also been linked to arrhythmias and sudden death.

OBJECTIVE

To assess whether OSA increases the risk of sudden death in the non-cardiac population.

METHODS

This is a systematic review of the literature. The descriptors "sudden death" and "sleep apnea" and "tachyarrhythmias" and "sleep apnea" were searched in the PubMed/Medline and SciELO databases.

RESULTS

Thirteen articles that addressed the relationship between OSA and the development of tachyarrhythmias and/or sudden death with prevalence data, electrocardiographic findings, and a relationship with other comorbidities were selected. The airway obstruction observed in OSA triggers several systemic repercussions, e.g., changes in intrathoracic pressure, intermittent hypoxia, activation of the sympathetic nervous system and chemoreceptors, and release of catecholamines. These mechanisms would be implicated in the appearance of arrhythmogenic factors, which could result in sudden death.

CONCLUSION

There was a cause-effect relationship between OSA and cardiac arrhythmias. In view of the pathophysiology of OSA and its arrhythmogenic role, studies have shown a higher risk of sudden death in individuals who previously had heart disease. On the other hand, there is little evidence about the occurrence of sudden death in individuals with OSA and no heart disease, and OSA is not a risk factor for sudden death in this population.

Comparison of frontal QRS-T angle of patients with nasal septal deviation with healthy controls

BACKGROUND

This study compares frontal QRS-T angle (fQRS-T) in electrocardiogram (ECG) examinations of people with nasal septal deviation (NSD) with healthy controls (HC).

METHODS

Eighty-two patients whom a radiologist with paranasal computed tomography definitively diagnosed with NSD were included in the study. 101 individuals without NSD were selected as HC.

RESULTS

Compared to the HC group, the fQRS-T in was considerably wider in patients with NSD (p < .001). According to Spearman correlation analysis, fQRS-T and NSD angle, and platelet lymphocyte ratio (PLR) were significantly correlated (p = .021, p < .001, and p = .003, respectively). In linear regression analysis where the fQRS-T was taken as a dependent variable, NSD angle and PLR predicted the fQRS-T significantly and positively (F(5.76) = 8.451, R2 = 0.357, Adjusted R2 = 0.315 and p < .001).

CONCLUSION

In this study, fQRS-T was significantly higher in patients with NSD. In future studies, fQRS-T can be compared before and after septoplasty in NSD patients.

Severity of spleep apnea syndrome and life-threatening tachyarrhythmias in patients with implantable cardioverter defibrillator

BACKGROUND

Sleep apnea syndrome (SAS) has been reported to be associated with a higher incidence of ventricular arrhythmias. The aim of this study was twofold: (1) to investigate whether in SAS patients receiving an implantable cardioverter defibrillator (ICD) the severity of SAS was associated with the occurrence of ventricular arrhythmias; (2) to assess whether changes in nocturnal apnoic/hypopnoic episodes may favor the occurrence of life-threatening arrhythmias, that is, sustained ventricular tachycardia (VT)/fibrillation (VF), requiring ICD intervention.

METHODS

We enrolled 46 patients with documented SAS at polysomnography (apnea/hypopnea index [AHI] > 5) who also had a left ventricle ejection fraction (LVEF) < 35% and, according to primary prevention indications, implanted an ICD (Boston Scientific Incepta) able to daily monitor apnoic/hypopnoic episodes occurring during sleep. Patients were followed at 3-month intervals.

RESULTS

At a mean follow-up of 18 months, 21 episodes of sustained VT/FV requiring ICD intervention were documented in eight patients (17.4%). Baseline AHI was significantly higher in patients with compared to those without ICD intervention. ICD interventions, however, were not preceded by any worsening of apnoic/hypopnoic episodes. The respiratory disturbance index (RDI) of the week during the event, indeed, was not different from that recorded during the previous 2 weeks (25.4 ± 11, 25.6 ± 10 and 25.1 ± 10, respectively; p = .9).

CONCLUSIONS

In patients with SAS who received an ICD for primary prevention of sudden death, those with ICD interventions showed a more severe form of the disease at baseline. ICD interventions, however, were not preceded by any significant changes in SAS severity.

Effects of Septoplasty on Tp-e Interval and Tp-e/QT Ratio in Patients With Nasal Septal Deviation

OBJECTIVES

There are multiple nasal airway pathologies leading to upper airway obstruction, and one of the most common ones is nasal septum deviation (NSD). Our study aimed to evaluate the effect of nasal septal surgery in patients with NSD on ventricular arrhythmogenesis using the novel electrocardiographic parameters, Tp-e interval, and Tp-e/QT ratio.

METHODS

This retrospective cross-sectional study included 102 consecutive patients diagnosed with NSD. All participants completed a validated outcomes instrument (the NOSE scale), echocardiographic and electrocardiographic evaluation before and 3 months after septoplasty. The degree of nasal septal deviation was evaluated with the Dreher classification.

RESULTS

All of the electrocardiography parameters (except heart rate and QTmin) were significantly decreased with the septoplasty operation. Electrocardiographic parameters have significantly decreased especially in marked NSD patients. (Δ = difference between the preoperative and postoperative values) ΔNOSE was positively correlated both ΔcTp-e (r = 0.348, P < .001) and ΔcTp-e/QT values (r = 0.536, P < .001).

CONCLUSION

Consequently, marked NSD was associated with increased risk of arrhythmogenesis, which were too much improved after septoplasty. So, treatment of especially marked NSD not only reduces otolaryngological complaints, but also leads to improvement of ventricular repolarization parameters.

The Influence of Sleep Apnea on 24-Hour and Nocturnal ECG and Blood Pressure Parameters in Patients with Acute Heart Failure

OBJECTIVE

To investigate the influence of sleep apnea (SA) on ECG and blood pressure (BP) monitoring parameters in patients with acute heart failure (AHF).

METHODS

A total of 51 hospitalized patients with AHF (13 women, 38 men, mean age 60.8 years) underwent 24-hour combined monitoring of ECG and BP and SA testing before discharge. Heart rhythm (mean heart rate, arrhythmias, pauses, QT interval, heart rate variability) and BP (mean systolic and diastolic values, variability, circadian variation) parameters were obtained for the whole day and for nighttime (22: 00-06: 00). Depending on SA severity, the patients were divided into two groups (respiratory event index, REI, < 15/h and ≥15/h). Comparisons of parameters between the two groups were performed using t test and χ2 test (alpha < 0.05 for significance).

RESULTS

A total of 29 (56.9%) patients had REI ≥15/h. In this group, the systolic and diastolic BP values (24-hour and nighttime) were significantly higher (p < 0.05). BP variability did not differ, and a markedly blunted circadian variation of both the systolic and diastolic values was observed. In the group with REI ≥15/h, we found a higher nocturnal versus diurnal mean heart rate ratio (p = 0.046) and a greater occurrence of nocturnal versus diurnal ventricular premature beats (p = 0.0098).

CONCLUSION

The presence of significant SA was found to influence the BP values and nocturnal ventricular ectopy in patients with stabilized AHF. SA, 24-hour ECG, and BP monitoring could provide important information with potential impact on patient management.

Effect of Septoplasty on the Heart Rate Variability in Patients With Nasal Septum Deviation

BACKGROUND

Nasal septum deformities (NSD) are one of the most common causes of upper airway obstruction. Heart rate variability (HRV) is a physiologic parameter that is affected by the balance between the sympathetic and parasympathetic tonus.

OBJECTIVE

The aim of this study was to evaluate the effects of a septoplasty operation on HRV parameters as assessed by 24 hours ambulatory Holter recordings in patients with NSD.

METHODS

The prospective study involved 54 consecutive patients (16 women and 38 men) who underwent septoplasty due to a marked C- or S-shaped NSD. Twenty-four-hour Holter monitoring was performed to all patients pre- and 2 months postseptoplasty operation. For the HRV analyses, the definitions of evaluated parameters were made according to the Task Force of European Society of Cardiology and the North American Society of Pacing and Electrophysiology on HRV.

RESULTS

Low-frequency norm () (73 [68-86] versus 78 [70-81], P = 0.039) values were significantly increased after septoplasty whereas changes in other parameters were not statistically significant.

CONCLUSION

The authors' study showed that low-frequency norm values were significantly increased after septoplasty operation in patients with NSD which may be interpreted as a decreased sympathetic tone.

Heart-Rate Variability-More than Heart Beats?

Heart-rate variability (HRV) is frequently introduced as mirroring imbalances within the autonomous nerve system. Many investigations are based on the paradigm that increased sympathetic tone is associated with decreased parasympathetic tone and vice versa. But HRV is probably more than an indicator for probable disturbances in the autonomous system. Some perturbations trigger not reciprocal, but parallel changes of vagal and sympathetic nerve activity. HRV has also been considered as a surrogate parameter of the complex interaction between brain and cardiovascular system. Systems biology is an inter-disciplinary field of study focusing on complex interactions within biological systems like the cardiovascular system, with the help of computational models and time series analysis, beyond others. Time series are considered surrogates of the particular system, reflecting robustness or fragility. Increased variability is usually seen as associated with a good health condition, whereas lowered variability might signify pathological changes. This might explain why lower HRV parameters were related to decreased life expectancy in several studies. Newer integrating theories have been proposed. According to them, HRV reflects as much the state of the heart as the state of the brain. The polyvagal theory suggests that the physiological state dictates the range of behavior and psychological experience. Stressful events perpetuate the rhythms of autonomic states, and subsequently, behaviors. Reduced variability will according to this theory not only be a surrogate but represent a fundamental homeostasis mechanism in a pathological state. The neurovisceral integration model proposes that cardiac vagal tone, described in HRV beyond others as HF-index, can mirror the functional balance of the neural networks implicated in emotion-cognition interactions. Both recent models represent a more holistic approach to understanding the significance of HRV.

Sleep-Disordered Breathing and Arrhythmia in Heart Failure Patients

Heart failure (HF) treatment remains complex and challenging, with current recommendations aiming at consideration and treatment of comorbidities in patients with HF. Sleep-disordered breathing (SDB) and arrhythmia come into play, as both are associated with quality of life deterioration, and morbidity and mortality increase in patients with HF. Interactions of these diseases are versatile and may appear intransparent in daily practice. Nevertheless, because of their importance for patients' condition and prognosis, SDB and arrhythmia individually, but also through interaction on one another, necessitate attention, following the fact that treatment is requested and desired considering latest research findings and outcomes.

Recurrent paroxysmal atrial fibrillation induced by marked hypoxia during sleep-disordered breathing

Sleep-disordered breathing (SDB) has a big impact on autonomic nervous activity and thus induces or deteriorates various cardiovascular diseases. We here describe a typical but rarely documented case which clearly indicates a strong link between SDB and cardiovascular disease. A 68-year-old woman complaining of frequent palpitations was referred to our institute. An electrocardiogram (ECG) at a previous clinic had shown atrial fibrillation, although it had already returned to sinus rhythm on arrival at our institute. Her body mass index was 32.5 kg/m² and she had a history of loud snoring. Simultaneous examinations of Holter ECG monitoring and ambulatory polysomnography (PSG) showed onset of paroxysmal atrial fibrillation following marked oxygen desaturation at midnight. In-hospital PSG revealed severe obstructive sleep apnea. A new device with desaturation triggered ambulatory blood pressure monitoring system performed 1 week later again showed a midnight onset of paroxysmal atrial fibrillation coincided with surge of blood pressure with marked desaturation. Her recurrence of palpitations had obviously decreased by continuous positive airway pressure therapy thereafter. <Learning objective: A clinician should suspect sleep-disordered breathing (SDB) behind cardiac arrhythmia, especially if it is nocturnal. Nocturnal hypertension especially in obese patients may indicate SDB. Successful therapy for SDB by such as continuous positive airway pressure therapy attenuates sympatho-excitation and would improve the result of treatment of the arrhythmia.>.

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.

Effects of Nasal Septum Deviation and Septoplasty on Cardiac Arrhythmia Risk

OBJECTIVE

Upper airway obstruction (UAO) can result in cardiac complications, including arrhythmias and sudden cardiac death. Nasal septum deviation (NSD) is a common cause of UAO. The aim of this study was to assess the risk of cardiac arrhythmias in patients with NSD. To assess this risk, we measured noninvasive indicators of atrial arrhythmia (P-wave dispersion [Pd]) and ventricular arrhythmia (corrected QT dispersion [QTcd]) and compared these values between NSD patients and healthy subjects.

STUDY DESIGN

Prospective study.

SETTINGS

Tertiary referral center.

SUBJECTS AND METHODS

This study included 53 consecutive patients who had underwent septoplasty due to marked NSD. Electrocardiographic records were used to determine Pd and QTcd values preoperatively and 6 months postoperatively. Fifty-three consecutive age- and sex-matched subjects without any UAO were also examined as a control group.

RESULTS

Preoperative Pd and QTcd values were significantly higher in NSD patients than in the control group (Pd: 57.40 ± 14.21 vs 34.11 ± 7.12 milliseconds, P < .001; QTcd: 81.77 ± 16.39 vs 50.25 ± 11.51 milliseconds, P < .001, respectively). In addition, Pd and QTcd values were significantly greater in preoperative NSD patients when compared with the same patients postoperatively (Pd: 57.40 ± 14.21 vs 36.32 ± 8.9 milliseconds, P = .013; QTcd: 81.77 ± 16.39 vs 55.76 ± 11.4 milliseconds, P = .012, respectively).

CONCLUSION

In conclusion, NSD patients are at risk for both atrial and ventricular cardiac arrhythmias; however, septoplasty in these patients can relieve UAO and reduce the risk of arrhythmias.