Sportmedizinische Aspekte kardialer Risikostratifizierung

The present study investigates the association of the predicted CHD-risk (PROCAM) with the individual endurance capacity and heart rate variability (HRV) in a population-based sample of sedentary elderly. After stratification, in 57 men (48.1+/-9.5 yrs.) with an overall PROCAM-risk <10% (28.7+/-10.9 points) and 22 men (54.5+/-7.7 yrs.) with a coronary 10-year risk > or =10% (50.8+/-5.6 points) cycle ergometries and short-term HRV analysis of time (RRMEAN, SDNN, RMSSD) and frequency domain parameters (LF, HF, TP, LF/HF) were conducted. Additionally the autonomic stress index (SI) was calculated. Nonparametric tests were used for statistical correlation analysis (Spearman rho) and group comparisons (Mann-Whitney). For endurance capacity [W/kg] (r=-0.469, p<0.001), SDNN (r=-0.302, p<0.05), RMSSD (r= -0.311, p<0.05), LF (r=-0.325, p<0.05), HF (r= -0.311, p<0.05) and TP (r= -0.307, p<0.05) negative monotone correlations with the coronary score-risk were determined. Significant positive correlations were calculated for SI (r=0.476, p<0.001). Except for RRMEAN and LF/HF significant group differences (p<0.05) were computed for SDNN (30.0+/-20.0 vs 20.0+/-10.0 ms), RMSSD (22.2+/-18.3 vs 18.0+/-8.7 ms), LF (90.9+/-241.5 vs 41.35+/-81.1 ms(2)), HF (43.0+/-105.1 vs 18.0+/-27.0 ms(2)) and TP (189.0+/-457.1 vs 100.0+/-157.6 ms(2)). Significant differences (p<0.01) were evaluated for exercise capacity (2.4+/-0.5 vs 1.8+/-0.3 W/kg) and SI (90+/-183 vs 322+/-291). The results underline the predictive value of HRV analysis in risk stratification and outline the interrelation of a decreased exercise capacity and autonomic function with a raised individual 10-year cardiac risk. As an independent parameter of the vegetative regulatory state the stress index may contribute to an increased practical relevance of short-time HRV analysis.     

Comparison of autonomic withdrawal in men with obstructive sleep apnea syndrome, systemic hypertension, and neither condition

Obstructive sleep apnea syndrome is characterized by obesity, nocturnal breathing abnormalities, arterial hypertension, and an increased number of cardiovascular events. Sympathetic activity is increased during nocturnal apneic episodes, which may mediate the cardiovascular complications of sleep apnea. We studied 15 male subjects with obstructive sleep apnea syndrome and associated hypertension, 54 subjects with mild to moderate essential hypertension, and 25 healthy normotensive men. Cardiovascular autonomic control was assessed using frequency domain measures of heart rate variability (HRV) during a controlled breathing test and during orthostatic maneuver. Compared with normotensive and hypertensive groups, total power and low- and high-frequency components of HRV during controlled breathing were significantly (analysis of variance, p<0.0001) lower in the obstructive sleep apnea syndrome. During the orthostatic maneuver, the change in total power of HRV was different between the 3 groups (analysis of variance, p = 0.004). The total power of HRV tended to increase in the normotensive (4.11+/-12.29 ms2) and in hypertensive (2.31+/-12.65 ms2) groups, but decreased (1.13+/-1.23 ms2) in the hypertensive group with obstructive sleep apnea syndrome. According to multivariate regression analysis, age and sleep apnea were the major independent determinants of HRV. This study found that an abnormal response to autonomic nervous tests characterizes hypertension in overweight subjects with obstructive sleep apnea syndrome. This could be due to autonomic withdrawal or supersaturation of the end-organ receptors by excessive and prolonged sympathetic stimulation. Our results also show the reduced response of orthostatic maneuver and controlled breathing in the hypertensive group compared with the normotensive group.     

Medroxyprogesterone in postmenopausal females with partial upper airway obstruction during sleep.

The aim of the present study was to evaluate the degree and duration of respiratory stimulation caused by medroxyprogesterone acetate (MPA), and compare the effect of MPA to that of nasal continuous positive airway pressure (nCPAP) in sleep-disordered breathing. Ten postmenopausal females with predominantly partial upper airway obstruction during sleep had an overnight sleep study at baseline, on the fourteenth day of treatment with MPA and after a 3-week washout period. Six subjects on nCPAP were also studied 3 months later. At baseline, the overnight mean+/-SD end-tidal pressure of carbon dioxide (Pet,CO2) was 5.5+/-0.4 kPa the arterial oxygen saturation (Sa,O2) 93.0+/-1.2%, Sa,O2 nadir 80.0+/-6.7%, and frequency of oxygen desaturation > or = 4% (ODI4) per hour 2.2+/-1.3. MPA decreased Pet,CO2 by 0.8 kPa (14.5%, p<0.001). After washout, the mean Pet,CO2 remained at 0.5 kPa (9.1%, p<0.001) lower than at baseline. Sa,O2 did not change. Pet,CO2 was lower on MPA than on nCPAP (4.7+/-0.2 kPa versus 5.0+/-0.3 kPa; p=0.037) but Sa,O2 was similar. Apnoea/hypopnoea index tended to be lower on CPAP than on MPA. Medroxyprogesterone acetate at a daily dose of 60 mg improves ventilation in postmenopausal females with partial upper airway obstruction during sleep without compromising sleep. The ventilatory improvement is sustained for at least 3 weeks posttreatment. Medroxyprogesterone acetate was more efficient in decreasing the partial pressure of carbon dioxide but continuous positive airway pressure was superior in decreasing respiratory efforts.     

Heart rate variability in heart failure

BACKGROUND: Heart rate variability (HRV) depicts the functional status of the autonomic nervous system and its effects on sinus node. Recently, HRV analysis has been introduced in patients with heart failure (CHF) to identify those who are at risk of cardiac death. AIM: To analyse HRV in patients with CHF with depressed left ventricular ejection fraction (EF) and to relate HRV parameters to EF, NYHA functional class and other clinical parameters. METHODS: The study group consisted of 105 patients with CHF (88 males, 17 females, mean age 54+/-12 years); 77 patients had ischaemic cardiomyopathy, and 28 - dilated cardiomyopathy. All patients were in NYHA class II-IV and had EF <40%. The mean value of echocardiographically assessed EF was 26.9+/-8.3%. The control group consisted of 30 gender- and age-matched healthy subjects. HRV analysis was performed in the time-domain from 24-hour Holter ECG. RESULTS: All HRV variables were significantly lower in patients with CHF than in controls. Patients with NYHA class II had higher values of SDNN and SDANN than those in class III or IV. Patients with sustained or non-sustained ventricular tachycardia (VT) detected during Holter monitoring had lower SDNN and SDANN values than those without VT. Patients with diabetes had significantly lower SDNN and rMSSD values than the patients without diabetes. Similar results were found when patients with or without hypertension were compared. HRV parameters were similar in patients either with ischaemic or dilated cardiomyopathy. Also the values of EF were similar (27.4+/-8.4 vs 25.0+/-8.3%, respectively, NS). In the whole group of patients with CHF the values of SDNN and SDANN significantly correlated with EF (SDNN p<0.001, r=0.42; SDANN p<0.001, r=0.51). This correlation was stronger in the subset of patients with ischaemic cardiomyopathy (SDNN p=0.002. r=0.54; SDANN p=0.002; r=0.53) than in those with dilated cardiomyopathy (SDNN p=0.012, r=0.23; SDANN p=0.008, r=0.42). A significant negative correlation was found between all HRV parameters and NYHA class (SDNN p<0.001, r = -0.33; SDANN p<0.001, r = -0.38; rMSSD p<0.001, r = -0.13). CONCLUSIONS: HRV is depressed in patients with CHF compared with healthy subjects. Among patients with CHF, HRV is further decreased in patients with more advanced NYHA class, lower EF and in those with diabetes, hypertension or VT on Holter monitoring.     

Einflu? von Carvedilol auf die Herzfrequenzvariabilit?t bei Patienten mit dilatativer Kardiomyopathie

The aim of the present study was to assess the effects of carvedilol therapy in addition to conventional heart failure therapy on heart rate variability (HRV) and on left ventricular function in 14 patients with mild to moderate heart failure due to idiopathic dilated cardiomyopathy (IDC). After a 3- to 4-week titration period, carvedilol was titrated up to 50mg daily, or the highest dose tolerated (at least 25mg daily). Maintenance treatment was then continued for 8 weeks. Digital 24-hour Holter recordings were obtained at baseline and after 8 weeks of carvedilol therapy. HRV for the entire 24-hour period was computed in the time domain using the Oxford Medilog Excel 2 analysis system. Measures of HRV included the mean of all coupling intervals between normal beats (RRm), the standard deviation of all normal RR intervals (SDNN), the square root of the mean of the squared differences between adjacent normal RR intervals (rMSSD), and the proportion of adjacent normal RR intervals differing >50 ms (pNN50). Additional treatment with carvedilol induced a significant increase in HRV: SDNN increased from 77+/-21 ms to 110+/-22 ms (p=0.001), rMSSD from 19+/-7 ms to 26+/-7 ms (p=0.02), and mean pNN50-value increased from 1.7+/-1.3% to 5.5+/-4.5% (p<0.01) under therapy with carvedilol. Mean heart rate on carvedilol calculated over 24 hours was 13 beats less than at baseline (75 bpm versus 88 bpm, p<0.01). After 2 months of additional treatment with carvedilol, both hemodynamic and clinical parameters improved: left ventricular ejection fraction increased from 24+/-7% to 30+/-10% (p<0.05), and New York Heart Association class decreased from 2.5+/-0.8 to 1.8+/-0.7 (p<0.05). In summary, eight weeks of additional carvedilol therapy induced a significant increase in HRV parameters related to parasympathetic activity in patients with IDC. Whether increased vagal tone may contribute to the protective effect of carvedilol has to be evaluated by further studies.     

Myocardial ischemia and autonomic activity in dippers and non-dippers with coronary artery disease: assessment of normotensive and hypertensive patients

OBJECTIVES: The aim of this study was to assess the relations between the circadian variations of blood pressure (BP) and the pattern of ischemia and autonomic activity in normotensive and hypertensive patients with coronary artery disease (CAD). PATIENTS AND METHODS: On the basis of the results of ambulatory BP monitoring, 115 patients with stable CAD were divided into Group 1 (with arterial hypertension) and Group 2 (normotensives). Groups were subdivided into dippers and non-dippers. Holter monitoring was performed to assess the occurrence and circadian pattern of ischemic episodes. Time domain and frequency domain HRV analyses were performed to evaluate the autonomic activity. RESULTS: The total number of ischemic episodes was similar in dippers and non-dippers. Non-dippers had a greater number of silent episodes and a different circadian pattern of ischemia with more night episodes. Among the time-domain HRV parameters, only SDNN was similar in dippers and non-dippers. Non-dippers had lower pNN50 and rMSSD-the parameters expressing parasympathetic activity. Differences between diurnal and nocturnal results of spectral HRV analysis were observed in dipper patients only. They presented an elevation of HF power and a decline of LF power at night. All differences between dippers and non-dippers were of similar significance in both hypertensives and normotensives. CONCLUSIONS: A lack of a nocturnal fall in BP is present in normotensive and hypertensive patients with CAD. Non-dippers with CAD had silent and nighttime ischemia more often. They also had an abnormal pattern of autonomic activity with higher sympathetic and lower parasympathetic modulation.     

Myocardial stress. Exercise versus sleep in patients with COPD

Epidemiologic investigation has revealed that patients with pulmonary disease are at increased risk of dying during the early morning hours. To provide a pathophysiologic explanation for these excessive nocturnal mortality statistics, we tested the hypothesis that episodes of arterial O2 desaturation during sleep can produce as severe a stress on the maintenance of myocardial O2 balance as maximal exercise in patients with chronic obstructive pulmonary disease (COPD). Thirty-one subjects with COPD underwent both overnight sleep and treadmill exercise study to their dyspnea-limited maximum. During both activities, systemic blood pressure was directly recorded and myocardial oxygen consumption (MVO2) estimated from the pulse rate (HR) - systolic blood pressure (SBP) product. Arterial O2 content (CaO2) was calculated from hemoglobin concentration and arterial O2 saturation (SaO2) measured by ear oximetry. Using these data and the Fick principle, myocardial blood flow (MBF) was continuously estimated during both exercise and sleep. During sleep, mean SaO2 was 88 +/- 7 percent while the average of the lowest SaO2 recorded for each subject was 71 +/- 14 percent. Episodes of nocturnal oxyhemoglobin desaturation produced consistent elevations in SBP frequently accompanied by an increase in HR. Because this hemodynamic response resulted in increased MVO2 at precisely the times when arterial O2 contents were low, high demands for MBF were generated. The average of the highest individual values for MBF during sleep was 244 +/- 144 (ml/100 g LV/min). This value was not significantly different from the value of MBF = 281 +/- 91 (ml/100 g LV/min) determined for maximal exercise. This finding suggests that the demand for coronary blood flow during episodes of nocturnal hypoxemia can be transiently as great as during maximal exercise in patients with COPD.     

Effectiveness of short-term treatment with nocturnal oxygen therapy for central sleep apnea in patients with congestive heart failure

OBJECTIVES. To evaluate the short term effects of inhalation of oxygen at night in 51 patients with congestive heart failure (CHF) and sleep apnea syndrome (SAS). METHODS. Fifty-one patients with stable CHF (31 males, 20 females, mean age 79.0 +/- 11.9 years; brain natriuretic peptide level of > 100 pg/ml) were evaluated between September 2003 and August 2004, using a Morpheus monitor. The complication rate of SAS in patients with CHF was assessed and apnea hypopnea index, oxygen desaturation index 3%, heart rate, and autonomic nerve activity under room air compared to supplemental O2 (2 l/min) over two consecutive nights. RESULTS. Thirty-eight (75%)of the CHF patients had SAS. Of these SAS patients, 49% suffered from central SAS and 51% had obstructive SAS. Apnea hypopnea index and oxygen desaturation index 3% improved remarkably with supplemental oxygen (p < 0.001), in particular, the central SAS group demonstrated prominent improvement (p < 0.001). Obstructive SAS patients exhibited no significant changes (p = 0.3356), but tended to exacerbate the episodes of sleep apnea. Total heart rate was decreased (p = 0.0079). Nevertheless, heart rate variability analysis showed little effect of nocturnal oxygen therapy on the autonomic nervous system during sleeping. CONCLUSIONS. Nocturnal oxygen therapy improved the number of sleep apnea episodes and decreased total heart rate during sleep time for the CHF patients with central SAS, despite little influence on the autonomic nervous system, based upon assessment of heart rate variability. Obstructive SAS might exacerbate the episodes of sleep apnea.     

心率变异性在糖尿病心脏自主神经病变中的临床意义

目的 利用动态心电图观测糖尿病患者心率变异性(HRV)的变化及诊断糖尿病心脏自主神经病变.方法 47例糖尿病患者和49例正常对照组记录24小时动态心电图,HRV时域分析指标为:正常R-R间期标准差(SDNN)、连续5分钟正常R-R间期标准差的均值(SDANNindex)及相邻正常R-R间期差值的均方根(rMSSD).结果 糖尿病患者HRV的各参数指标SDNN(86.06±35.97)ms、SDANNindex(77.83±34.72)ms、rMSSD(21.11±18.20)ms均低于正常对照组,差异有显著性意义.有糖尿病周围神经病变或眼低病变的患者各参数指标较无并发症者低,差异有显著性意义.糖尿病组rMSSD病变发生率最高(46.81%),这与糖尿病早期出现迷走神经病变相一致.结论HRV作为一种测量心脏自主神经的定量检测方法,具有灵敏、简便、无创伤性的特点,为早期发现糖尿心脏自主神经障碍,及早防治糖尿病严重并发症的发生提供了一个良好的工具.     

Cardiac autonomic tone and its relation to nonsustained ventricular tachyarrhythmias in idiopathic dilated cardiomyopathy

BACKGROUND: In contrast to postinfarct patients, little is known about cardiac autonomic tone and its relation to spontaneous ventricular tachyarrhythmias in idiopathic dilated cardiomyopathy (IDC). Both heart rate variability (HRV) and baroreflex sensitivity (BRS) are indices of autonomic innervation of the heart. HYPOTHESIS: The aim of the present study was to determine the relation between cardiac autonomic tone assessed by HRV and BRS and spontaneous nonsustained ventricular tachycardia (NSVT) on Holter in a large patient population with IDC. METHODS: 24-h digital Holter recordings including HRV analysis and BRS testing were prospectively performed in 137 patients with IDC and preserved sinus rhythm. Mean age was 48 +/- 12 years, and mean left ventricular (LV) ejection fraction was 32 +/- 9%. The HRV analysis on Holter included the mean RR interval (RRm), the standard deviation of all normal RR intervals (SDNN), the square root of the mean of the squared differences between adjacent normal RR intervals (rMSSD), and the proportion of adjacent normal RR intervals differing more than 50 ms (pNN50). Testing for BRS was performed noninvasively using the phenylephrine method. RESULTS: Of 137 study patients, 42 (31%) had spontaneous NSVT on 24-h Holter. Compared with patients without NSVT, patients with NSVT on Holter had a higher New York Heart Association (NYHA) functional class (NYHA III: 40 vs. 18%, p < 0.01), a lower ejection fraction (29 +/- 9 vs. 34 +/- 9%, p = 0.01), and an increased LV end-diastolic diameter (69 +/- 8 mm vs. 66 +/- 7 mm, p = 0.03). The HRV variables rMSSD, pNN50, RRm, and BRS did not differ significantly between patients with and without spontaneous NSVT. Only SDNN on Holter was slightly lower in patients with versus without NSVT (106 +/- 45 vs. 121 +/- 46 ms, p = 0.08). CONCLUSIONS: Patients with IDC and spontaneous NSVT on Holter are characterized by a higher NYHA functional class, a lower LV ejection fraction, an increased LV end-diastolic diameter, and a tendency toward a lower SDNN value compared with patients without NSVT. The remaining measures of HRV including rMSSD and pNN50 reflecting primarily tonic vagal activity, as well as BRS reflecting predominantly reflex vagal activity, were similar in patients with and without NSVT. The prognostic significance of these findings in patients with IDC is currently under investigation in the Marburg Cardiomyopathy Study (MACAS) at our institution.     

Breathing pattern abnormalities and arterial oxygen desaturation during sleep in the congestive heart failure syndrome. Improvement following medical therapy

We observed breathing pattern abnormalities and arterial oxygen desaturation in patients with stable congestive heart failure during overnight polysomnography. To determine whether congestive heart failure was the reason for these abnormalities, we then studied six additional patients before and after treatment of heart failure. Breathing was more abnormal (153 +/- 87 episodes/night) during decompensation of heart failure and improved with medical therapy (72 +/- 100 episodes/night) (p less than 0.05). Abnormal breathing patterns resolved in three patients, improved in two, and were unchanged in one patient after therapy. Allographic cardiac transplantation in one patient whose sleep study remained unchanged after medical therapy was associated with resolution of breathing pattern abnormalities and severe desaturation during sleep. Therapy-related improvement in nocturnal respiratory events suggests congestive heart failure is a contributing factor for breathing abnormalities and arterial oxygen desaturation during sleep.     

Correlation between cardiac autonomic activity and compromise of left ventricular function in dilated cardiomyopathy

In recent years, evaluation of cardiac autonomic activity by means of heart rate variability (HRV) determination and baroreflex sensitivity (BRS) testing has become readily available. The results of the ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study showed that both diminished HRV and baro-reflex sensitivity are associated with poor outcome in patients after myocardial infarction. In contrast to patients with coronary disease little information is available concerning cardiac autonomic activity in idiopathic dilated cardiomyopathy (IDC). Therefore, HRV and BRS were assessed in 160 patients with IDC and preserved sinus rhythm in order to investigate the relationship between HRV, BRS, and left ventricular ejection fraction. Time domain indices of HRV were computed from 24-hour digital Holter recordings. BRS testing was performed using the noninvasive phenylephrine method. Mean standard deviation of all normal RR intervals (SDNN) of the whole study population was 112 +/- 46 ms. A well preserved HRV (SDNN > 105 ms) was found in 74 patients (46%), a moderately decreased HRV (SDNN 70-105 ms) in 59 patients (37%), and a severely decreased HRV (SDNN < 70 ms) in 27 patients (17%). Mean BRS was 7.5 +/- 5.0 ms/mm Hg. A well preserved BRS (> 6 ms/mm Hg) was present in 78 patients (57%), a moderately decreased BRS (3-6 ms/mm Hg) was present in 38 patients (28%), and a severely decreased BRS (< 3 ms/mm Hg) in 21 patients (15%). There was only a weak correlation between SDNN and BRS (r = 0.19; p < 0.05). A weak correlation was found for SDNN and left ventricular ejection fraction (r = 0.29; p < 0.05). There was no significant correlation between BRS and left ventricular ejection fraction (r = 0.14). In summary, there was only a weak correlation between the HRV, BRS, and left ventricular ejection fraction in patients with IDC suggesting that these 3 variables may be independent predictors of sudden death in IDC. The relative prognostic value of these variables and other potential risk predictors including the presence of arrhythmias on Holter, microvolt T wave alternans, QTc dispersion, and signal-averaged ECG is currently under investigation in a large prospective observational study (Marburg Cardiomyopathy Study (MACAS)) during 5-year follow-up at our institution.     

睡眠呼吸暂停综合征对高血压病患者血压昼夜节律及心率变异性的影响

目的探讨阻塞性睡眠呼吸暂停（OSAS）对高血压病患者血压昼夜节律及心率变异性（HRV）的影响。方法入选62例高血压病患者,根据是否合并OSAS分为：单纯组（无合并OSAS）及合并组（合并OS-AS）,另选择同期30名健康人群作为对照组。比较三组患者呼吸紊乱指数（AHI）、夜间平均血氧水平、昼间及夜间血压水平、非杓型血压的比例、HRV频域指标（SDNN、PNN50）与时域指标（低频谱、高频谱）的差异。结果合并组与单纯组、对照患者比较夜间平均血氧水平、AHI、HRV频域指标（SDNN、PNN50）与时域指标（低频谱、高频谱）差异均有显著统计学意义（P均〈0.01）;合并组非杓型血压的比例显著高于其他两组,差异有显著统计学意义（P〈0.01）。结论 OSAS增加高血压病患者血压昼夜节律异常及心率变异性。     

Comparison of the effects of ipratropium bromide and salbutamol on autonomic heart rate control.

AIMS: B2-agonists and anticholinergic drugs may alter cardiac autonomic modulation. The aim of this study was to investigate the effects of inhaled salbutamol and ipratropium bromide on heart rate variability (HRV). METHODS AND RESULTS: A randomized, double-blind, crossover design study was conducted on 13 healthy volunteers. Salbutamol, ipratropium or placebo was administered in three different testing sessions. Time domain parameters; mean R-R interval (mean-RR), the standard deviation of R-R interval (SDNN) and the root mean square of successive R-R interval differences (RMSSD) and power spectral analysis of HRV were assessed in the supine position and during handgrip exercise before and after taking each drug. In time domain analyses, ipratropium administration resulted in a reduced mean-RR, SDNN and RMSSD during handgrip exercise compared with baseline values (775 +/- 30 ms vs. 748 +/- 21 ms, P < 0.05; 57 +/- 5 ms vs. 50 +/- 5 ms, P < 0.05; 30 +/- 2 ms vs. 26 +/- 2 ms, P < 0.01, respectively). This effect was not detected with salbutamol or placebo administration. In frequency domain analyses, salbutamol but not ipratropium and placebo inhalation increased high frequency power/total power during handgrip exercise compared with baseline (0.09 +/- 0.02 vs. 0.12 +/- 0.02, P < 0.05). CONCLUSION: Ipratropium inhalation may alter autonomic control of the heart rate in therapeutic doses during mild sympathetic stimulation in healthy subjects, while salbutamol does not show these effects.     

Domiciliary investigation of sleep-related hypoxaemia in Duchenne muscular dystrophy.

In Duchenne muscular dystrophy (DMD) nocturnal oxygen desaturation occurs during rapid eye movement (REM) sleep. Polysomnography, which requires hospital admission, will detect sleep-related breathing abnormalities. In order to avoid the inconvenience of hospital admission for the disabled patient, we investigated overnight oxygenation in ten boys with DMD by domiciliary oximetry. In four boys the results of oximetry were compared with those of a polysomnographic recording. The "repeatability" of domiciliary oximetry was assessed in six boys by performing oximetry on two non-consecutive nights. Older boys with DMD may develop a cardiomyopathy. In order to assess cardiac rhythm and ST segment changes we performed simultaneous Holter monitoring and oximetry in seven boys with overnight hypoxaemia. Six of the initial ten boys studied demonstrated episodic nocturnal hypoxaemia and there was a strong correlation between minimum oxygen saturation overnight and daytime arterial oxygen and carbon dioxide tensions (PaO2 r = 0.89; PaCO2 r = -0.87). Despite adequate REM time during polysomnography, greater oxygen desaturation was found during domiciliary oximetry. No difference was found in the severity of desaturation recorded in the boys who were studied on two separate occasions. Five boys demonstrated marked heart rate variation during hypoxaemic episodes and more serious arrhythmias occurred overnight in the three most hypoxaemic boys. Domiciliary oximetry is a simple, repeatable method of assessing overnight oxygenation and compares well with polysomnography. In boys with advanced DMD and severe nocturnal hypoxaemia, 24 h electrocardiographic monitoring may detect potentially life-threatening arrhythmias.     

Effects of nocturnal oxygen therapy on outcome measures in patients with chronic heart failure and cheyne-stokes respiration.

BACKGROUND: The effects of nasal oxygen (O(2)) supply at night using conventional home oxygen therapy (HOT) equipment on quality of life (QOL) and sleep-disordered breathing (SDB) were evaluated in patients with congestive heart failure (CHF). Nasal nocturnal O(2) therapy not only stabilizes SDB but also reduces sympathetic activity, and improves exercise capacity in patients with CHF. However, the effects of oxygen on the cardiac function and QOL of heart failure patients have not been fully elucidated. METHODS AND RESULTS: Fifty-six patients with CHF (New York Heart Association class II - III, left ventricular ejection fraction (LVEF) 相似文献   

老年高血压合并糖尿病患者心率变异性及其昼夜变化临床分析

目的研究老年高血压合并糖尿病患者的心率变异性(HRV)及其昼夜变化规律,探讨老年糖尿病患者心脏自主神经变化的临床意义。方法选择87例原发性高血压患者(EH组)及68例高血压合并糖尿病患者(EH+DM组),监测24 h动态心电图,进行HRV时域指标SDNN、SDANN、SDNN Index、RMSSD、PNN50的分析。比较2组间HRV指标的差异以及HRV昼夜指标差异。结果 EH+DM组较EH组24 h、日间、夜间HRV各项指标均明显降低,且有统计学差异;EH组SDNN以及RMSSD呈昼低夜高,但无明显统计学差异,SDNN Index和PNN50仍呈昼低夜高现象(P0.01);EH+DM组SDNN以及RMSSD呈昼高夜低现象(P0.05),SDNN Index和PNN50昼夜间无统计学差异。结论老年高血压合并糖尿病患者HRV显著降低,高血压患者昼夜节律已有明显受损,高血压合并糖尿病患者昼夜节律进一步受损,心脏自主神经功能失调。     

Assessment of autonomic function in patients with acute myocardial infarction or diabetes mellitus by heart rate variability, ventricular late potential and QT dispersion.

To compare the efficacy and sensitivity of heart rate variability (HRV), QT dispersion (QTd) and ventricular late potential (VLP) examination in judging autonomic function. Thirty three patients with acute myocardial infarction (AMI) and 33 patients with diabetes mellitus (DM), all of whom were diagnosed with autonomic neuropathy determined by a standard test of cardiovascular autonomic function, were examined by HRV (timing domain methods), QTd and VLP. Thirty three normal individuals served as controls. The mean SD of the normal R-R interval (SDNN) in both the AMI and DM groups was significantly less than that in the control group (p< 0.01); and of course, the QTd of these groups was significantly greater than that of the controls (p< 0.01). The VLP positive rate of the AMI and DM groups were much higher than that of the control group (p< 0.001). SDNN was shown to be significantly negatively correlated to QTd (r= -0.45); and significantly negatively correlated to VLP (r= -0.47); QTd was shown to be positively, though not significantly, correlated to VLP (r=0.48). QTd could be looked as sieving index; HRV could be looked as routine examination of cardiovascular autonomic function, especially SDNN; the combination of HRV and VLP could improve the accuracy of diagnosis.     

Altered heart rate variability but preserved temporal relationship with sleep stages in a patient with primary aldosteronism

OBJECTIVE: In a previous study, we found oscillations in the autonomic nervous system activity--as estimated by spectral analysis of R-R intervals--strongly linked to the non-rapid-eye movement (NREM)--REM sleep cycles, with low sympathetic activity during NREM sleep and predominant sympathetic activity during REM sleep. In the present study we established the 5-min nighttime profiles in various measures of heart rate variability (HRV) in one patient with primary aldosteronism before and after successful surgery of Conn adenoma. METHODS: One patient (female, 36 years old) with primary aldosteronism underwent two experimental nights a few weeks before and after surgery by coeliscopy in which sleep and cardiac recordings were made. Power spectral analysis was performed on ectopic-free R-R intervals with a fast Fourier transform. We calculated also the standard deviation of normal R-R intervals (SDNN) and the root mean square difference among successive R-R intervals (RMSSD). RESULTS: While removal of adenoma resulted in a rapid complete normalization of blood pressure and classical signs and biological symptoms of aldosterone hypersecretion, HRV profile did not changed a few weeks after surgery. The overnight SDNN was low although not abnormal at 38 and 33 ms before and after surgery respectively vs 58 +/- 15 ms (33 to 83) in normal female controls. RMSSD was low although not abnormal at 33 and 31 ms before and after surgery respectively vs 60 +/- 20 ms (20 to 105). The total spectrum power was low although not abnormal at 2.3 and 1.8 ms2 before and after surgery, respectively vs 3.2 +/- 1.1 ms2 (1.4 to 4.9). One out of the 8 controls had comparable or lower SDNN (33 ms), RMSSD (20 ms) and total power (1.4 ms2) values. While LF/HF ratio was comparable, the VLF (0.003-0.04 Hz) and LF (0.04-0.15 Hz) relative power were decreased and increased respectively in the patient compared in controls. Despite this reduced HRV, the normal temporal relationship of spectral parameters with specific sleep stages was preserved. CONCLUSION: Altered HRV with normal temporal relationships with specific sleep stages was observed in a patient with primary hyperaldosteronism. This HRV profile did not changed 20 weeks after successful surgery i.e. complete remission of classical signs and symptoms of aldosterone hypersecretion.     

Predictive value of heart rate variability for the recurrence of chronic atrial fibrillation after electrical cardioversion

BACKGROUND: The relation between heart rate variability (HRV) and occurrence of atrial fibrillation (AF) in paroxysmal AF has been well studied, but there are controversial observations regarding the relation of HRV parameters to the recurrence of chronic AF after cardioversion. HYPOTHESIS: The present study compared HRV parameters of patients with chronic AF on the second day of cardioversion with a healthy control group and investigated their predictive value for AF recurrence. METHODS: Forty-one patients with chronic AF (> 3 months), who had various underlying cardiovascular disorders, were enrolled to the study. Of these, 31 patients were successfully cardioverted by external direct current shock, but 27 patients fulfilled the entry criteria. Twenty healthy subjects served as a control group. On the second day of restoration of sinus rhythm, 24-h Holter recording was obtained and the following time-domain indices of HRV were measured: SDNN (the standard deviation of the mean RR interval expressed in ms), SDANN (the SD of the averages of RR intervals in all 5-min segments of the 24-h recording), rMSSD (the root mean square of differences of successive RR intervals), and pNN50 (the percentage of adjacent RR intervals that differed by more than 50 ms). Patients were followed-up for 6 weeks for recurrence of AF. RESULTS: After cardioversion, SDNN and SDANN were found to be significantly lower in the AF group than in the control group (86.4 +/- 31.7 ms vs. 142.1 +/- 40.2 ms, and 57 +/- 17.4 ms vs. 124.4 +/- 37.7 ms, p < 0.001 and p < 0.001, respectively). The indices of vagal modulation of heart rate (rMSS and pNN50) were not different between the AF group and the control group. Recurrence of AF was observed in 15 patients. In these patients, all HRV parameters were significantly depressed compared with those with maintained sinus rhythm. Logistic regression analysis revealed that only decreased pNN50 was an independent predictor of AF relapse (relative risk = 1.5, p = 0.02, 95% confidence interval 1.1-2.2). There was also a trend toward a shortened SDNN as a predictor of AF recurrences. CONCLUSION: Suppressed HRV parameters and decreased vagal tone are probably a risk factor for AF recurrences after cardioversion to sinus rhythm in a specific subset of patients with chronic AF.