Diagnosis of sleep-disordered breathing in patients with chronic heart failure: evaluation of a portable limited sleep study system

Sleep-disordered breathing (SDB) is common in chronic heart failure (CHF), affects disease progression and presents a potential therapeutic target. This study was designed to test the hypothesis that there would be good agreement in diagnostic outcome between home limited sleep studies and in-laboratory polysomnography (PSG) in the identification of SDB in patients with CHF. We performed synchronous in-laboratory Embletta and PSG, and home Embletta studies, prospectively in 20 consecutive patients with stable symptomatic CHF (ejection fraction 33 +/- 12%) on optimal medical therapy. Sleep efficiency was poor at 57 +/- 21%. Unlike synchronous in-laboratory Embletta (kappa coefficient 0.63, P < 0.01), home Embletta showed poor agreement with PSG (kappa coefficient 0.27, P = 0.06). Positive and negative predictive values for home Embletta in detecting SDB were 83% and 57% respectively. In this relatively small study, agreement in diagnostic outcome between home Embletta and PSG, and negative predictive value for the home Embletta, were poor. We explore possible explanations for this, both technical and situational, which should be taken into consideration when considering potential screening or diagnostic tools for SDB in patients with CHF.     

Measures of cognitive function in persons with varying degrees of sleep-disordered breathing: the Sleep Heart Health Study

Epidemiologic literature suggests that persons with clinically diagnosed sleep apnoea frequently have impaired cognitive function, but whether milder degrees of sleep-disordered breathing (SDB) are associated with cognitive dysfunction in the general population is largely unknown. Approximately 1700 subjects free of clinically diagnosed SDB underwent at-home polysomnography (PSG) as part of the Sleep Heart Health Study (SHHS) and completed three cognitive function tests within 1-2 years of their PSG: the Delayed Word Recall Test (DWR), the WAIS-R Digit Symbol Subtest (DSS), and the Word Fluency test (WF). A respiratory disturbance index (RDI) was calculated as the number of apnoeas and hypopnoeas per hour of sleep. After adjustment for age, education, occupation, field centre, diabetes, hypertension, body-mass index, use of CNS medications, and alcohol drinking status, there was no consistent association between the RDI and any of the three cognitive function measures. There was no evidence of a dose-response relation between the RDI and cognitive function scores and the adjusted mean scores by quartiles of RDI never differed from one another by more than 5% for any of the tests. In this sample of free-living individuals with mostly mild to moderate levels of SDB, the degree of SDB appeared to be unrelated to three measures of cognitive performance.     

Association of breathing movements to the variability of heart rate and blood pressure in foetal lambs

Heart rate (HR) variability and arterial blood pressure (BP) variability were analysed as functions of foetal breathing movements (FBMs) by means of power spectral analysis in seven foetal lambs during the third trimester of gestation. No evidence of FBM-related changes, either in mean HR, mean systolic or diastolic arterial pressures, were found. Mean arterial pulse pressure, HR variability, and BP variability increased during FBMs. The increase in BP variability occurred at frequencies higher than 0.35 Hz, i.e. those of FBMs. The increase in HR variability occurred at 0.07-1.0 Hz, i.e. at every frequency band except the lowest one. Thus, the increase in HR variability was not frequency-specifically related to FBMs. During FBMs the periodic variability of HR at frequencies > 0.35 Hz was only 10% of total HR variability. We suggest that the FBM-related changes of BP variability may be mediated by direct peripheral, hydraulic mechanisms. HR changes involve autonomic control systems: the vagal component of baroreflex seems to be relatively insensitive, whereas the very slow vasomotor component of HR variability is dominant.     

Association of cardiac autonomic function measures with severity of sleep-disordered breathing in a community-based sample

The goal of this study was to test the hypothesis that spectral indices of heart rate variability, such as high-frequency power (HFP), low-to-high frequency power (LHR), and their respiration-adjusted counterparts (HFPra, LHRra) are correlated with severity of sleep-disordered breathing (SDB), as quantified by the respiratory disturbance index (RDI). A total of 436 subjects, non-smoking, normotensive, and free of cardiovascular disease and diabetes were selected from the Sleep Heart Health Study (SHHS). Of these, 288 records with sufficiently high quality electrocardiogram signals were selected for further analysis [males/females: 221/67; age: 46.1 to 74.9 years; body mass index (BMI): 21.5 to 46.4 kg m⁻²; 0.3 < RDI < 85.0⁻¹]. From each polysomnogram, the respiration channels (thoracic and abdominal) and R-R interval (RRI) derived from the electrocardiogram were subjected to spectral analysis and autoregressive moving average modeling in consecutive 5-min segments. After adjusting for age and BMI, mean RRI was found to be negatively correlated with RDI in men in all sleep-wake states (all P  < 0.001). HFP and HFPra were negatively correlated with RDI in men only during wakefulness (all P  < 0.01). In women, LHR and LHRra were not correlated with RDI during wakefulness, but were positively correlated during non-rapid eye movement Stage 1 and 2 sleep (all P  < 0.01). These findings suggest that the indices of cardiac autonomic control are correlated with SDB severity, but gender and state affect the nature of these correlations. In both genders, however, vagal modulation of heart rate increases while sympathetic modulation decreases from wakefulness to sleep.     

Sleep-disordered breathing in a general heart failure population: relationships to neurohumoral activation and subjective symptoms

The aim of this study was to determine the prevalence of sleep-related breathing disorders (SDB) in a UK general heart failure (HF) population, and assess its impact on neurohumoral markers and symptoms of sleepiness and quality of life. Eighty-four ambulatory patients (72 male, mean (SD) age 68.6 (10) yrs) attending UK HF clinics underwent an overnight recording of respiratory impedance, SaO2 and heart rate using a portable monitor (Nexan). Brain natriuretic peptide (BNP) and urinary catecholamines were measured. Subjective sleepiness and the impairment in quality of life were assessed (Epworth Sleepiness Scale (ESS), SF-36 Health Performance Score). SDB was classified using the Apnoea/Hypopnoea Index (AHI). The prevalence of SDB (AHI > 15 events h(-1)) was 24%, increasing from 15% in mild-to-moderate HF to 39% in severe HF. Patients with SDB had significantly higher levels of BNP and noradrenaline than those without SDB (mean (SD) BNP: 187 (119) versus 73 (98) pg mL(-1), P = 0.02; noradrenaline: 309 (183) versus 225 (148) nmol/24 h, P = 0.05). There was no significant difference in reported sleepiness or in any domain of SF-36, between groups with and without SDB (ESS: 7.8 (4.7) versus 7.5 (3.6), P = 0.87). In summary, in a general HF clinic population, the prevalence of SDB increased with the severity of HF. Patients with SDB had higher activation of a neurohumoral marker and more severe HF. Unlike obstructive sleep apnoea, SDB in HF had little discernible effect on sleepiness or quality of life as measured by standard subjective scales.     

Psychophysiological effects of slow-paced breathing at six cycles per minute with or without heart rate variability biofeedback

Heart rate variability (HRV) biofeedback, referring to slow-paced breathing (SPB) realized while visualizing a heart rate, HRV, and/or respiratory signal, has become an adjunct treatment for a large range of psychologic and medical conditions. However, the underlying mechanisms explaining the effectiveness of HRV biofeedback still need to be uncovered. This study aimed to disentangle the specific effects of HRV biofeedback from the effects of SPB realized alone. In total, 112 participants took part in the study. The parameters assessed were emotional (valence, arousal, and control) and perceived stress intensity as self-report variables and the root mean square of the successive differences (RMSSD) as a physiologic variable. A main effect of condition was found for emotional valence only, valence being more positive overall in the SPB-HRVB condition. A main effect of time was observed for all dependent variables. However, no main effects for the condition or time x condition interaction effects were observed. Results showed that for PRE and POST comparisons (referring, respectively, to before and after SPB), both SPB-HRVB and SPB-NoHRVB conditions resulted in a more negative emotional valence, lower emotional arousal, higher emotional control, and higher RMSSD. Future research might investigate psychophysiological differences between SPB-HRVB and SPB-NoHRVB across different time periods (e.g., long-term interventions), and in response to diverse psychophysiological stressors.     

Night-to-night alterations in sleep apnea type in patients with heart failure

In patients with heart failure, apnea type can shift overnight from mainly obstructive to mainly central in association with reductions in PCO(2) and increases in periodic breathing cycle length, indicative of a fall in cardiac output. We hypothesized that the predominant apnea type could also vary from one night to another in association with alterations in PCO(2) and cycle length. We studied 12 men with heart failure in whom the predominant apnea type changed from one night to the next over periods of at least 1 month, and two groups with either predominantly obstructive or central sleep apnea (OSA or CSA) in whom apnea type remained stable over time. In patients with unstable apnea type (n = 12, duration between sleep studies 9.0 +/- 4.4 months), PCO(2) was significantly lower (37.6 +/- 1.6 mmHg versus 41.7 +/- 1.9 mmHg, P < 0.01), and cycle length significantly longer (61.9 +/- 3.4 s versus 51.0 +/- 1.9 s, P < 0.001) during nights with predominantly central than nights with predominantly obstructive apnea. In contrast, in both the stable central (n = 8, duration between sleep studies 11.9 +/- 5.3 months) and the stable obstructive (n = 8, duration between studies 6.9 +/- 5.2 months) sleep apnea groups, neither PCO(2) nor cycle length changed significantly between the baseline and follow-up sleep studies. We conclude that in some patients with heart failure, OSA and CSA are part of a spectrum of periodic breathing that can shift over time in association with alterations in PCO(2), cycle length and probably cardiac function.     

心率变异性多参数分析的BP网络用于心衰诊断的研究

人工神经网络是由大量并行工作的神经元组成的智能仿生模型,它在模式识别领域已经展示出了广阔的应用前景。鉴于单一心率变异性(HRV)指标所表达出来的信息具有片面性,很难用一个单一的指标来完全分类充盈性心衰(CHF)患者和健康人的不足。本研究提出联合HRV信号分析的时域、频域、非线性方法,选取多个指标作为诊断CHF的特征参数,以BP神经网络为分类器实现对充盈性心衰的诊断。经过10 000次的训练、验证与仿真测试,该网络模型对于全样本集的识别正确率最优高达99.14%,平均可达86.97%。结果表明:联合线性(时域、频域)以及非线性分析方法可以更全面地揭示心脏的动力学特征,从而提高充盈性心衰的诊断正确率。     

Sleep apnea in heart failure increases heart rate variability and sympathetic dominance

AIMS: Sleep disordered breathing (SDB) is common in heart failure and ventilation is known to influence heart rate. Our aims were to assess the influence of SDB on heart rate variability (HRV) and to determine whether central sleep apnea (CSA) and obstructive sleep apnea (OSA) produced different patterns of HRV. METHODS AND RESULTS: Overnight polysomnography was performed in 21 patients with heart failure and SDB. Two 10-minute segments each of SDB and stable breathing from each patient were visually identified and ECG signal exported for HRV analysis. SDB increased total power (TP) with very low frequency (VLF) power accounting for the greatest increase (1.89+/-0.54 vs 2.96+/-0.46 ms2, P <0.001); LF/HF ratio increased during SDB (1.2+/-1.0 vs 2.7+/-2.1, P <0.001). Compared to OSA, CSA was associated with lower absolute LF (2.10+/-0.47 vs 2.52+/-0.55 ms2, P = 0.049) and HF power (1.69+/-0.41 vs 2.34+/-0.58 ms2, P = 0.004), increased VLF% (78.9%+/-13.4% vs 60.9%+/-19.2%, P = 0.008), decreased HF% (6.9%+/-7.8% vs 16.0%+/-11.7%, P = 0.046) with a trend to higher LF/HF ratio. CONCLUSIONS: SDB increases HRV in the setting of increased sympathetic dominance. HRV in CSA and OSA have unique HRV patterns which are likely to reflect the different pathophysiological mechanisms involved.     

Heart rate variability during sleep in children with partial epilepsy

Alterations in autonomic control of cardiac activity in epileptic patients have been reported by several studies in the past, and both ictal and interictal modifications of heart rate regulation have been described. Alterations of autonomic control of cardiac activity can play an important role in sudden unexplained death in patients with epilepsy (SUDEP). However, the presence of specific changes in heart rate variability (HRV) during sleep, not correlated with seizures, has not been assessed in children with epilepsy; for this reason, we evaluated features of cardiac autonomic function during sleep without ictal epileptiform electroencephalogram (EEG) activity in a group of children with partial epilepsy. Eleven patients (five males and six females; mean age 11.5 years, SD: 3.65 years) affected by partial epilepsy were admitted to this study; 11 normal subjects (five males and six females; mean age 12.9 years, SD: 2.72 years) served as a control group. All subjects slept in the laboratory for two consecutive nights. The data were analyzed during the second night. Sleep was polygraphically recorded [including one electrocardiography (ECG) channel] and signals were digitally stored. A series of 5-min ECG epochs were chosen from each sleep stage, during periods without evident ictal epileptiform activity in the EEG. Electrocardiography signals were analyzed for automatic detection of R-waves and, subsequently, a series of time- and frequency-domain measures were calculated. Epileptic subjects tended to show an overall lower HRV in both time- and frequency-domain parameters, principally during rapid eye movement (REM) sleep and, to a lesser extent, during sleep stage 2. Among the different bands, this decrease was most evident for the high-frequency band (HF) absolute power. For this reason, the ratio between the low-frequency band (LF) and HF was always higher in epileptic patients than in normal controls and the difference was statistically significant during sleep stages 3 and/or 4 and REM sleep. Our results indicate that during sleep, a particular condition of basal modification in autonomic characteristics occurs (mostly during REM sleep) in partial epilepsy patients. This finding might represent an important factor contributing to the complex mechanism of SUDEP which takes place most often during sleep and supports the need of studying HRV specifically during this state in subjects with seizures.     

Coping and mortality among patients with congestive heart failure

This study was undertaken to evaluate the effects of different coping styles on mortality risk among patients with symptomatic congestive heart failure (CHF). Proportional hazard models were used to evaluate the effects of different coping styles on mortality among 119 clinically stable patients (71.4% men, mean age 65.7 ± 9.6 years), recruited from an outpatient cardiology practice. Twenty deaths were registered during the 24-month period of data collection, all from cardiac causes. The findings showed that behavioral disengagement was a significant predictor of mortality with a hazard ratio of 1.64 (p ≤ .049), whereas acceptance of the CHF condition showed a marginally significant association with mortality (hazard ratio .64; p ≤ .09). The results suggest that behavioral disengagement in relation to coping with disease-related strain is a significant predictor of mortality among heart failure patients. This finding is of concern to clinicians and should have implications for treatment of patients with CHF. Given the link between behavioral disengagement and mortality demonstrated in this study, it is important to explore ways in which counseling in active coping skills might help patients who behaviorally disengage to manage their disease and thereby increase their longevity.     

Combined index of heart rate variability and oximetry in screening for the sleep apnoea/hypopnoea syndrome

Many sleep centres employ a preliminary screening test in order to reduce the number of polysomnographies required in the routine diagnosis of the sleep apnoea/hypopnoea syndrome (SAHS). We investigated the combination of heart rate and oximetry information as a means of performing this test. A retrospective study of 100 patients with suspected SAHS was made. All patients had in-hospital polysomnography on one night. We estimated the number of respiratory event-related arousals by counting the number of autonomic arousals (assessed on the basis of changes in the heart interbeat interval) that were coincident with a rise in oximetry. The hourly index of such events was denoted the "cardiac-oximetry disturbance index" (CODI). The median apnoea/hypopnoea index (AHI) was 16.5 (range 1.0-93.6) h-1. The CODI correlated significantly with the AHI (Spearman correlation coefficient rs = 0.88, P < 0.01), and the area (+/- standard error) under the receiver operating characteristic (ROC) was 0.94 +/- 0.05. Oximetry alone (based on 4% dips) was a less effective screening test (rs = 0.80, P < 0.01; area under ROC 0.83 +/- 0.06). Using 2% dips in oximetry offered comparable performance with the CODI (rs = 0.91, P < 0.01; area under ROC 0.93 +/- 0.04). The CODI was better correlated with the electroencephalograph arousal index (rs = 0.84, P < 0.01) than was oximetry (2% dips, rs = 0.57, P < 0.01). The CODI algorithm also offers an informal measure of self-validation: a large discrepancy between the number of autonomic arousals and the number of rises in oximetry indicates the presence of autonomic arousals without changes in oximetry (or vice versa). This self-validation mechanism identified several patients in this study, and may be useful in identifying sleep disruption due to chronic pain or other causes.     

慢性心力衰竭患者血浆瘦素水平的变化

目的： 研究慢性心力衰竭（CHF）患者血浆瘦素（leptin）水平的变化。方法：应用放射免疫法测定了60例CHF患者和26例健康对照者的血浆瘦素水平，比较CHF组与对照组、CHF组不同心衰级别及不同病因亚组间的血浆瘦素水平。结果：CHF组患者血浆瘦素水平明显高于对照组（P＜0.01）；心功能Ⅳ级患者的血浆瘦素水平明显高于心功能Ⅲ级患者（P＜0.01）；CHF不同病因亚组间血浆瘦素水平无显著差异（P＞0.05）。结论：CHF患者血浆瘦素水平升高，并与心衰的严重程度相关，而与引起心衰的病因无关。     

Daytime sleepiness and neural cardiac modulation in sleep-related breathing disorders

Sleep-related breathing disorders are common causes of excessive daytime sleepiness, a socially and clinically relevant problem. Mechanisms responsible for daytime sleepiness are still largely unknown. We investigated whether specific alterations in autonomic cardiac modulation during sleep, commonly associated with sleep-related breathing disorders, are related to excessive daytime sleepiness. Fifty-three patients with sleep-related breathing disorders underwent nocturnal polysomnography. Excessive daytime sleepiness was diagnosed as a Multiple Sleep Latency Test response less than or equal to 600 s. We explored the relation of excessive daytime sleepiness, objectively determined, with indices of autonomic cardiac regulation, such as baroreflex sensitivity and heart rate variability, with polysomnographic indices of the severity of sleep-related breathing disorders and with quality of sleep. Patients with excessive daytime sleepiness, when compared with patients without, had significantly lower baroreflex sensitivity and significantly higher low-to-high frequency power ratio of heart rate variability during the different stages of nocturnal sleep. By contrast, no differences were found in indices quantifying the severity of sleep-related breathing disorders or sleep quality. We demonstrated that excessive daytime sleepiness is accompanied by a deranged cardiac autonomic control at night, the latter probably reflecting autonomic arousals not detectable in the EEG. As abnormal autonomic regulation is also known to be associated with increased cardiovascular risk, a possible relation between excessive daytime sleepiness and cardiovascular events in patients with sleep-related breathing disorders deserves to be investigated in future studies.     

Nonlinear analysis of heart rate variability of healthy subjects and patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is one of the causes of mortality worldwide with an increasing prevalence. Heart rate variability (HRV) reflects the regulation mechanism of the cardiac activity by the autonomic nervous system. The assessment of HRV by using nonlinear methods is more sensitive for the detection of complexity when compared to linear methods. This study aims to get information about the autonomic dysfunction occurred in patients with COPD by analysing the complexity of HRV. Electrocardiogram signals recorded from healthy subjects, patients with moderate COPD and severe COPD (eight subjects per group) were analysed. The HRV signals were acquired from ECG signals. Signals were reconstructed in the phase space and largest Lyapunov exponent (LLE), correlation dimension, Hurst exponent and approximate entropy (ApEn) values were calculated. It has seen that for the patients with COPD LLE, correlation dimension, Hurst exponent and ApEn values were less than control group. According to this, HRV complexity decreases in the presence of COPD. However, there is no significant difference between COPD groups and the severity of COPD has no effect on the chaoticity of the system. The results revealed that autonomic dysfunction occurred in patients with COPD is associated with reduced HRV complexity.     

Heart rate variability spectra based on non-equidistant sampling: the spectrum of counts and the instantaneous heart rate spectrum

This paper compares two methods to estimate heart rate variability spectra, i.e., the spectrum of counts and the instantaneous heart rate spectrum. Contrary to Fourier techniques based on equidistant sampling of the interbeat intervals, the spectrum of counts and the instantaneous heart rate spectrum are based on non-equidistant sampling: the values are determined at R-wave moments. A consequence of the non-equidistant occurrence of the R-peaks in a heart rate signal is the appearance of the sidebands of the harmonic components of the mean heart rate in the spectra. These sidebands contaminate the signal components in the spectrum. The sideband distortion in the instantaneous heart rate spectrum was found to be smaller than in the spectrum of counts. Simulations using the IPFM-model were made to quantify this difference. On the basis of these simulations, sideband distortion appeared to be dependent on the mean heart rate, the modulation depth and the modulation frequency.     

以短时心率变异性反映充血性心力衰竭患者自主神经活动的改变

基于短时心率变异性（HRV）分析,探讨充血性心力衰竭（CHF）患者自主神经活动的变化和影响。选用THEW数据库中正常人子数据库作为正常对照组（n=189）,对于PhysioNet中两个CHF子数据库的样本（n=44）,按照NYHA等级,将NYHA I-II级划分轻度CHF 组（n=12）,NYHA III-IV级为重度CHF组（n=32）。对每一个Holter记录选取日间和夜间安静态各5 min的RR间期（RRI）序列,分别进行时域、基于AR模型的频域和去趋势波动（DFA）分析。在正常组、轻度CHF组和重度CHF组等三组中,CHF患者日间的短时分形尺度指数（(α₁)_d）两两比较均有显著性差异,并存在下降趋势（依次分别为1.35±0.21、1.03±0.29和0.81±0.29）,反映心率动力学从分形特性转向更随机化的结构。同时,日间HFn((HFn)_d)在三组间的两两比较中均存在显著性差异,并存在上升趋势（依次分别为23.89%±12.78%、37.22%±11.24%和56.30%±15.28%）, 表明CHF导致交感神经和迷走神经交互作用趋于消失。利用夜间RRI（RRI_n）,(HFn)_d 和 (α₁)_d等3个指标进行Fisher线性判别,区分正常人和CHF患者的灵敏性和特异性分别为90.91%和92.06%,而区分轻度和重度CHF患者的灵敏性和特异性分别为84.38%和100%。所进行的研究将HRV非线性方法与传统方法相结合评估自主神经状态, 为监测CHF病情或观察治疗效果等潜在的临床应用提供了依据。     

Cyclic alternating pattern and spectral analysis of heart rate variability during normal sleep

The natural arousal rhythm of non-rapid eye movement (NREM) sleep is known as the cyclic alternating pattern (CAP), which consists of arousal-related phasic events (Phase A) that periodically interrupt the tonic theta/delta activities of NREM sleep (Phase B). The complementary condition, i.e. non-CAP (NCAP), consists of a rhythmic electroencephalogram background with few, randomly distributed arousal-related phasic events. Recently, some relation between CAP and autonomic function has been preliminarily reported during sleep in young adults by means of spectral analysis of heart rate variability (HRV). The present study was aimed at analysing the effects of CAP on HRV in a group of normal children and adolescents. Six normal children and adolescents (age range 10.0-17.5 y) were included in this study. All-night polygraphic recordings were performed after adaptation to the sleep laboratory. Six 5-min epochs were selected from sleep Stage 2 and six from Stages 3 and 4 (slow-wave sleep), both in CAP and NCAP conditions. From such epochs, a series of parameters describing HRV was then calculated, in both time and frequency domains, on the electrocardiographic R-R intervals. Statistical comparison between CAP and NCAP epochs revealed a significant difference for most of the frequency domain parameters (increase of the low-frequency band, increase of the low-frequency/high-frequency ratio and decrease in the high-frequency band during CAP) both in Stage 2 and in slow-wave sleep. Our results demonstrate that the physiological fluctuations of arousal during sleep described as CAP are accompanied by subtle, but significant, changes in balance between the sympathetic and vagal components of the autonomic system.     

Diabetes mellitus and congestive heart failure: the prevalence of congestive heart failure in patients with and without diabetes in Poland

IntroductionDiabetes mellitus is a systemic disease and has a negative effect on the cardiovascular system. This paper aimed to present a retrospective analysis of morbidity associated with heart failure in subgroups of patients with and without diabetes in Poland in 2012.Material and methodsData from the National Health Fund were used for the study. In general, 656,937 patients with heart failure, including 281,538 males and 375,354 females, were studied. In this population, additionally, 201,043 patients with heart failure (main diagnosis) and diabetes were studied, including 82,117 males and 118,926 females.ResultsThe mean index of morbidity associated with heart failure in the whole subpopulation of diabetes patients was 9.03%; 8.42% for males and 9.50% for females. Morbidity associated with heart failure in the population of patients diagnosed with diabetes in Poland in 2012 was seven times higher compared to morbidity associated with heart failure in non-diabetes patients. Morbidity associated with heart failure in females was significantly higher compared to morbidity in males in the whole population, in both the subpopulations of patients with and without diabetes.ConclusionsDiabetes mellitus significantly increases risk of heart failure in both women and men. The risk is significantly high after the age of 60 years and higher in females.     

Association of right ventricular dysfunction and Cheyne-Stokes respiration in patients with chronic heart failure

Cheyne-Stokes respiration (CSR) is present in up to 40% of patients with congestive heart failure (CHF) and is an independent risk factor for increased overall mortality. We examined whether CSR is associated with right ventricular (RV) dysfunction in CHF patients. Parameters of RV function were assessed by two-dimensional echocardiography and tissue velocity imaging in 42 patients (aged 23-75 years) with a left ventricular (LV) ejection fraction below 40%. Respiratory polygraphy revealed CSR with an central apnea-hypopnea index (CAHI) >10 h-1 in 13 of the 42 patients (31%). Demographic characteristics did not differ among the patient groups. The velocity of the tricuspid annular systolic motion (TASM), a parameter reflecting systolic RV function, was significantly reduced in CHF patients with CSR (10.5 +/- 2.3 cm s-1) compared with those without CSR (15.0 +/- 5.1 cm s-1, P = 0.004), and was inversely associated with the CAHI (y = 15.2-0.2x; r = 0.46, P = 0.003). The RV dimensions were significantly increased and the fractional RV area changes significantly reduced in CHF patients with CSR (33 +/- 17 versus 48 +/- 20%; P = 0.04). Doppler parameters of pulmonary artery flow indicate higher pulmonary artery pressures in CSR patients compared with patients without CSR, which is also reflected by an increased RV free-wall thickness in CSR patients (6.5 +/- 1.1 vs. 5.3 +/- 1.3 mm; P = 0.05). Parameters of systolic LV function, forced expiratory volume in 1 s (FEV1), and PaO2 and PaCO2 were not different among patients with or without CSR. In conclusion, CSR is associated with depressed systolic RV function and increased RV dimensions in CHF patients. Future studies will show whether optimized treatment of CSR will improve RV function.