慢性肺心病患者的心率变异性

目的：观察慢性肺心病患者心率变异性，了解其自主神经功能的变化。方法：对25例慢性肺心病，25例健康对照者（对照组）作前瞻性对照研究，记录24h动态心电图，作时域和频域分析，结果：与对照组比较，肺心病组相邻心搏的R－R间期之差＞50ms的心搏数占R－R间期数的百分(pNN50)，每5min正常R－R间期标准差的平均值（SDANN），频域指标的高频（HF）明显降低，低频与高频的比值（LF／HF），明显升高，差异均有非常显著意义（P均＜0．01），而频域指标的低频（LF）无明显变化（P＞0．05），经过治疗后，肺心病组处于缓解期，与治疗前比较，HF，PNN50，SDANN等指标明显增加，而LF／HF明显降低，差异均有非常显著意义（P均＜0．01），肺心病组病人治疗后HF，pNN50,SDANN等指标均低于对照组，而LF／HF明显高于对照组，差异均有非常显著意义（P均＜0．01），肺心病组治疗后LF与治疗前及对照组比较，差异不具显著意义（P＞0．05）。结论：肺心中层得不仅交感神经活动占优势，同时并存迷走神经功能受损，自主神经功能可能存在连续性障碍。     

慢性心力衰竭患者的心率变异性分析

目的探讨慢性心力衰竭患者的心率变异性特点及心功能损害程度与心率变异性的相关性.方法对69例慢性心力衰竭患者和52例健康对照者的心率变异性资料进行对比分析,比较不同程度心功能不全患者的心率变异性差异.结果心力衰竭组正常R-R间期总体标准差、相邻正常R-R间期差值的均方根、相邻正常R-R间期差值〉50 ms的窦性心搏占心搏总数的百分比、总功率、低频功率和高频功率低于健康对照组,低频与高频功率比值高于健康对照组（P〈0.01）.随着心功能受损程度加重,心力衰竭患者的心率变异性进一步减低,其中低频功率较敏感.结论检测心率变异性在心力衰竭患者中的变化可反映自主神经功能受损情况,同时为心力衰竭程度的预测和治疗提供有用的参考指标.     

Heart rate variability following neonatal heart surgery for complex congenital heart disease

BACKGROUND: Altered cardiac autonomic control may play a role in the morbidity and mortality suffered by neonates who undergo surgery for complex congenital heart disease (CHD). The purpose of this study was to evaluate cardiac autonomic activity, as measured by spectral indices of heart rate variability (HRV), prior to and early after infant surgery for CHD and attempt to correlate HRV indices with clinical outcome. In addition, we assessed the hypothesis that single-ventricle physiology and surgical interruption of the great arteries negatively affects HRV. METHODS: Sixty neonates prospectively wore 24-hour Holter monitors at three time points: before and early after CHD surgery, and at 3- to 6-month follow-up. Standard spectral indices of HRV were measured. RESULTS: In the early postoperative time point, patients with single-ventricle physiology had lower low-frequency power (LF) compared to patients with two ventricles (P=0.040). Surgical interruption of the great arteries did not affect HRV in this cohort. For the entire cohort, LF (P=0.004) and high-frequency power (HF) (P<0.001) increased over the three time points, while LF/HF (P=0.119) did not significantly change. In the multivariable linear regression model, significant predictors of longer postoperative hospital stay included longer total support time (P=or<0.001), longer duration of inotrope support (P=0.012), elevated mean heart rate at postoperative time point (P=0.002), and lower LF/HF ratio at the postoperative time point (P=0.014). CONCLUSION: Patients with single-ventricle physiology have a significant physiologic reduction in LF in the early postoperative period compared to patients with two ventricles. Diminished cardiac autonomic control is associated with longer hospitalization following neonatal cardiac surgery.     

Postresuscitation autonomic nervous modulation after cardiac arrest resembles that of severe sepsis

Introduction

This study explored whether post-resuscitation status resembles severe sepsis in terms of autonomic nervous modulation by using heart rate variability (HRV) analysis.

Methods

Successfully resuscitated nontraumatic out-of-hospital cardiac arrest (OHCA) adult patients in an emergency department were prospectively enrolled as the study group. Age- and sex-matched patients with severe sepsis with and without mechanical ventilation were included as positive controls, while sepsis patients and healthy volunteers were included as negative controls. The HRV measures obtained from 10-minute electrocardiogram were compared among 5 groups of subjects.

Results

Sixty-four successfully resuscitated OHCA patients were studied. There were no significant differences in all HRV measures (standard deviation of R-R intervals [SD_RR], coefficient of variation of R-R intervals [CV_RR], total power [TP], very-low-frequency component [VLF], low-frequency component [LF], high-frequency component [HF], normalized LF [LF%], normalized HF [HF%], and LF/HF) among the successfully resuscitated OHCA patients and severe sepsis patients with and without mechanical ventilation. Also, no significant differences in all HRV measures were found between nonsurvivors of OHCA group and nonsurvivors of severe sepsis group. In the nonsurvivors of OHCA group and severe sepsis group, the LF% and LF/HF were significantly lower, whereas the HF and HF% were significantly higher, as compared with the survivors of these 2 groups.

Conclusions

The autonomic nervous modulation in the initial phase of OHCA patients resembles that of severe sepsis in that both groups of patients have decreased global HRV (TP, SD_RR, and CV_RR), sympathovagal balance (LF% and LF/HF), and renin-angiotensin-aldosterone modulation (VLF), as compared to healthy subjects.     

Heart rate variability during sleep and sleep apnoea in a population based study of 387 women

Increased sympathetic activity during sleep has been suggested as a link between obstructive sleep apnoea syndrome and cardiovascular disease. Heart rate variability (HRV) is a measure of autonomic effect on the heart. Different parameters have been associated with sympathetic and parasympathetic activity. We have studied HRV in different sleep stages and related the HRV‐pattern to sleep apnoea in a population‐based sample of 387 women. We investigated the HRV‐parameters standard deviation of all R‐R intervals (SDNN), root of the averaged square of successive differences (RMSSD), low frequency component (LF), high frequency component (HF), ratio of low frequency component to high frequency component LF/HF and VSAI [variation in sympathetic activity between rapid eye movement (REM) and slow wave sleep, defined as LF_REM?LF_SWS]. The HRV‐parameters were compared with the results of a full‐night polysomnography. Hourly incidence of obstructive episodes was used for classifying the subjects into four apnoea‐hypopnoea index (AHI)‐groups (<5, ≥5 and <15, 15–30 and >30 events). Individual sleep stages were analysed by pooling all recordings. Women with high AHI had higher heart rate and LF/HF ratio. In subjects with AHI >30, LF/HF ratio however dropped to same level as with AHI <5. Subjects with high AHI had low VSAI. Levels of SDNN, LF and LF/HF ratio during REM and light sleep were similar to wakefulness. In slow wave sleep the parameters decreased. In conclusion, moderately increased prevalence of obstructive apnoeas was associated with signs of higher sympathetic activity. High AHI was however associated with a HRV‐pattern suggestive of depressed sympathetic drive and lowered ability to increase it during REM.     

Assessment of autonomic nervous system functions in patients with vitamin B12 deficiency by power spectral analysis of heart rate variability

The purpose of this study was to test the autonomic nervous system function of patients with vitamin B12 deficiency (megaloblastic anemia) by measuring heart rate variability (HRV). The study population consisted of 17 vitamin B12 deficient patients and 15 age- and sex-matched normal volunteers. HRV was measured by power spectral analysis from which power of the low frequency (LF) peak (0.04-0.15 Hz), normalized units of the LF peak (LFNU), power of the high frequency (HF) peak (0.15-0.4 Hz), normalized units of the HF (HFNU), and ratio of power of LF to power of HF (LF:HF) were calculated. Vitamin B12 deficient patients had lower LF, LFNU, HF, HFNU, and LF:HF ratio than normal volunteers (P < 0.05). Decreases in sympathetic indices (LF and LFNU) were greater than those measured in parasympathetic indices (HF and HFNU). All HRV parameters correlated positively with the level of vitamin B12 (P < 0.001) and negatively with the duration of disease (P < 0.001). After vitamin B12 replacement the HRV parameters of patients and controls became comparable (P > 0.05). Our data suggest that autonomic sympathetic and parasympathetic nervous activities are decreased in patients with vitamin B12 deficiency, an abnormality that can be corrected by vitamin B12 replacement therapy.     

Effects of glucose ingestion on cardiac autonomic nervous system in healthy centenarians: differences with aged subjects

BACKGROUND: Spectral analysis of heart rate variability (HRV) investigates the cardiac autonomic nervous system (ANS) activity. In particular, low frequency/high frequency (LF/HF) is considered an index of cardiac sympatho-vagal balance and is stimulated by glucose ingestion in healthy subjects. No studies have evaluated the effect of glucose ingestion on cardiac ANS in centenarians. MATERIALS AND METHODS: In 30 healthy centenarians (HC) and 25 aged subjects (AS) power spectral analysis of HRV was investigated during an oral glucose ingestion. RESULTS: Glucose ingestion rose LF/HF ratio in both groups studied. Such stimulatory effects were restrained to the first 60 min of the study. Independent of age, gender, body mass index (BMI) and fasting plasma norepinephrine and FT3 concentrations, HC had basal total power (1318 +/- 546 vs. 1918 +/- 818 msec2, P < 0.01), lower low frequency (LF) (33 +/- 21 vs. 50 +/- 11 n.u., P < 0. 03), and higher high frequency (HF) (74 +/- 18 vs. 43 +/- 15 n.u., P < 0.05) than AS. Consequently, LF/HF ratio (0.43 +/- 0.07 vs. 0.91 +/- 0.05, P < 0.02) was also lower in HC than in AS. In AS, but not in HC, the baseline LF/HF ratio correlated significantly with BMI (r = 0.48, P < 0.01), waist-hip-ratio (WHR) (r = 0.45, P < 0.02), fasting plasma insulin (r = 0.49, P < 0.01) and norepinephrine (r = 0.57, P < 0.02) concentration. Glucose ingestion was associated with a significant rise in LF/HF ratio in both groups studied but per cent changes in glucose mediated stimulation of LF/HF was lower in HC than in AS. In a control study, water administration did not affect power spectral parameters of HRV. CONCLUSION: Our study demonstrates that basal- and glucose-stimulated LF/HF, an indirect index of cardiac sympatho-vagal balance, are lower in HC than in AS.     

急性冠脉综合征心率震荡昼夜节律及其与心率变异的相关性分析

目的 研究急性冠脉综合征患者心率震荡(heart rate turbulence,HRT)的昼夜节律性,并通过HRT指标与心率变异性指标的相关性分析,进一步探讨HRT与自主神经的关系.方法 连续入选急性冠脉综合征患者91例,分析一天中的两个时段即白天(7: 00～19: 00)和夜间(0: 00～6: 00)HRT的变化.从上午7: 00和凌晨0: 00开始各按顺序入选3个室早,根据文献计算HRT指标[震荡初始(TO)、震荡斜率(TS)]的数值.心率变异性选用的时域指标有SDNN、RMSSD,频域指标包括LF、HF、LF/HF.结果 ①TO值白天较夜间高,TS值白天较夜间低,均存在明显的昼夜节律.②TS与SDNN之间存在正相关关系(r=0.44),TS与LF/HF之间亦存在正相关关系(r=0.51).结论 急性冠脉综合征HRT存在昼夜节律变化且与HRV密切相关,提示HRT不仅反映心血管系统自主神经的反射性调节,在某种程度上也反映交感-迷走神经的紧张性调节.     

Autonomic involvement in idiopathic premature ventricular contractions

Objective

To investigate autonomic involvement in different types of idiopathic premature ventricular contractions (PVCs) grouped by heart rate (HR) dependency.

Methods

One hundred and sixty PVC patients and 31 controls were enrolled. Holter ECG was used to evaluate PVC occurrence, and spectral analysis of heart rate variability (HRV) was calculated to represent cardiac autonomic control. PVCs were divided into fast rate-dependent (F-PVC), slow rate-dependent (S-PVC), and HR-independent PVC (I-PVC) based on the relationship between hourly PVC density and hourly HR. HRV among different types of PVCs were compared, and the association between PVC density with HR and HRV were analyzed. Furthermore, autonomic changes assessed by consecutive 5-min HRV in 30 min before PVC episodes were investigated.

Results

In 160 subjects, there were 73 F-PVC, 56 S-PVC, and 31 I-PVC. Hourly PVC density was positively associated with sympathetic indice (LF/HF) and negatively related to vagal indices (HF and HFnu) in F-PVC, and this trend was reversed in S-PVC. During 30 min before PVC onset, RR interval and HFnu decreased significantly with LF/HF showing an increasing trend in F-PVC, while in S-PVC both RR interval and HF increased significantly. It was noted that those changes were most evident during the last 5 min before PVC onset. In addition, PVC density in F-PVC was significantly decreased by β-blocker treatment.

Conclusions

HR dependency reflected autonomic modulation of idiopathic PVCs. F-PVC and S-PVC might be facilitated by sympathetic activation and vagal activation, respectively. HR dependency and the related autonomic mechanisms should be considered when treating idiopathic PVCs.     

The effects of therapeutic ultrasound on heart rate variability: a placebo controlled trial

The effect of therapeutic ultrasound (US) on nervous system is controversial and the effect on autonomic nervous system is not clear. Therefore, the present placebo-controlled trial was planned to investigate the effects of therapeutic US application on right-side stellate ganglion, by using analysis of heart rate variability (HRV). A total 12 healthy volunteers were included in the study. RR intervals were recorded for 5 min before and after the US application, in supine and sitting positions. All procedures were repeated in all participants with sham US one week later. The heart rate (HR) was obtained by time-domain analysis and low frequency (LF) power (%), high frequency (HF) power (%) and LF/HF ratio values were obtained by frequency-domain (power spectral density) analysis. After the US application, there was a decrease in the HR (p = 0.002) and the HF power (%) component (p = 0.015) in supine position and a decrease in HR (p = 0.002) and LF/HF ratio (p = 0.028) in sitting position. There was no significant difference after the sham US application. In conclusion, we observed that therapeutic US application on stellate ganglion causes alterations on HRV parameters.     

体外循环先天性心脏病纠治术对心率变异性的影响

目的探讨体外循环心内直视手术创伤对心脏自主神经系统的影响。方法观察30例先天性心脏病房、室间隔缺损患者行心内修补术术前、术中及术后7d的心率变异性变化。结果术中及术后4d内低频(LF)、高频(HF)和总频(TP)较术前明显下降(P＜0.05),术中体外循环结束时达最低值(P＜0.01),术后第7天恢复接近至术前水平,总体表现为一个缓慢上升的趋势。结论心脏手术、体外循环、低温、主动脉阻断及药物因素可导致心率变异性下降,而术后心脏自主神经系统的恢复是一个缓慢的过程。     

腹腔镜手术对小儿心率变异性的影响

目的观察腹腔镜手术下小儿心率变异性（Heart rate variability，HRV）的变化，为小儿术中及术后心血管的康复提供依据。方法选择ASAⅠ或Ⅱ级择期行腹腔镜手术的患儿20例，全部采用静吸复合全麻，气管内插管，呼吸机行间歇正压通气。分别于麻醉前、气腹前、气腹5min、气腹20min、气腹30min和放气腹5min观察心率变异性指标总功率（TP）、高频功率（HF）、低频功率（LF）、低频标准化值（LFNU）、高频标准化值（HFNU）和低频高频功率比（LF／HF）的变化。结果与气腹前比较，TP、LF、LFNU和LF／HF显著升高（P〈0．01），Hk，无明显变化（P〉0．05）。结论腹腔镜手术气腹后小儿交感神经占优势。HRV可作为麻醉循环监测的敏感指标，动态反映小儿自主神经的变化。     

Using 100% oxygen does not alter the cardiovascular autonomic regulation during non-invasively simulated haemorrhage in healthy volunteers

We tested the effect of 100% oxygen on heart rate (HR), arterial blood pressure (ABP), cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), HR variability (HRV), systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS) in 20 healthy volunteers during simulated haemorrhage induced by -40 mmHg lower body negative pressure (LBNP). HRV in the high frequency region (HRV HF), BRS, ABP and TPR were significantly increased, SBPV in the low frequency region (SBPV LF), CO and SV were unchanged, and HR was significantly decreased by 100% oxygen administration during normovolaemia. HRV HF, BRS, CO and SV were significantly decreased, SBPV LF and ABP were unchanged, and HR and TPR were significantly increased by LBNP during 21% or 100% oxygen administration. There were no significant differences in cardiovascular autonomic and haemodynamic responses to LBNP during 21% or 100% oxygen administration, suggesting that 100% oxygen does not alter normal cardiovascular autonomic responses during simulated haemorrhage.     

Heart rate variability and its determinants in patients with severe or mild essential hypertension

How cardiac autonomic nervous control is related to the severity of essential hypertension in patients receiving long‐term antihypertensive therapy is not well known. The aim of this study was to examine heart rate variability (HRV), a non‐invasive measure of cardiac autonomic function, in patients with long‐term and medically treated mild and severe essential hypertension and healthy control subjects, and to assess the clinical determinants of HRV in these patients. Thirty‐four patients with severe essential hypertension (SEHT) and 29 with mild essential hypertension (MEHT) as well as healthy age‐ and sex‐matched control subjects were studied. HRV was assessed from 10 min ECG‐recordings during paced (0·2 Hz) breathing at rest and expressed as time and frequency domain measures. In the SEHT group time (SDNN, RMSSD) and frequency domain measures (total power, low‐frequency (LF) power and high‐frequency (HF) power of HRV in absolute units, and LF and HF power of HRV in normalized units) of HRV were significantly lower when compared with those of the control group. The MEHT and control groups did not differ from each other with respect to time or frequency domain measures of HRV. Comparison between the hypertensive groups showed that SDNN, total power, LF power and HF power were lower in the SEHT group compared with the MEHT group (P<0·05 for all). Among hypertensive patients RR‐interval, age, gender, systolic finger blood pressure and diastolic office blood pressure as well as 24‐h blood pressure were significant determinants of HRV. In conclusion, we found that the severity of chronic essential hypertension seems to be related to the severity of impairment of cardiac autonomic control.     

Chronotropic incompetence to exercise separates low body weight from established anorexia nervosa

Chronotropic incompetence (CI), characterized by an attenuated heart rate (HR) response to exercise could participate to the limitation of exercise capacity in anorexia nervosa (AN). Therefore, we evaluated the role of cardiac sympathetic responsiveness in AN patients. In addition, the ambulatory value of autonomic control using spectral analysis of heart rate variability (HRV) was determined and correlated to maximal exercise performance. Twenty-two patients hospitalized for weight loss and suspicion of AN were included in the study. All performed a symptom-limited exercise test with measurement of gas exchange for chronotropic response to exercise evaluation. Holter ECG recordings allowed daytime and night-time spectral domain HRV analysis in order to evaluate the alteration of sympathetic control of HR in free-living conditions. CI defined as a failure to achieve 80% of heart rate reserve (%HRR) was observed in 13 (59%) patients (CI+). This group presented a higher body mass deficit than the group without CI (CI-; -35.1 +/- 8.7% versus -26.1 +/- 10.7%; P<0.05). Obviously, patients with a lower body mass index (BMI < 16 kg m(-2), n = 14) revealed a more severe limitation to maximal exercise with a lower peak HR, a lower peak Vo(2), and a lower maximal O(2) pulse (P<0.05). BMI was significantly correlated to peak Vo(2), maximal HR, and %HRR achieved at peak exercise. Daytime HRV parameters reflecting the sympathetic autonomic equilibrium (LF nu, LF/HF ratio) were significantly lower in CI+ patients. Blunted sympathetic response to maximal exercise is frequent and correlated to weight deficit. The present data suggest a major autonomic derangement in AN characterized by a cardiac sympathetic withdrawal.     

Is There Increased Sympathetic Activity in Patients with Mitral Valve Prolapse?

The aim of this study was to investigate autonomic nervous system tone in patients with mitral valve prolapse (MVP). Heart rate variability (HRV) was assessed from 24-hour ambulatory Holter recordings in 28 patients with primary MVP and in 28 age and sex matched normal control subjects in a drug-free state. Sixteen of the MVP patients were symptomatic and 12 asymptomatic. Spectral HRV was calculated in terms of low (LF: 0.06–0.15 Hz) and high (HF: 0.15–0.40 Hz) frequency components using fast Fourier transform analysis, and the ratio LF/HF was calculated. Spectral analysis of HRV showed that the MVP patients, taken as a single group, had lower HF and LF and a higher LF/HF ratio than the controls. No significant difference in HRV was found between the 16 symptomatic and the 12 asymptomatic patients, but the symptomatic patients had a significantly higher LF/HF ratio than the controls. Our observations suggest that, during normal daily activities, patients with MVP experience a significant deviation in autonomic nervous system tone with predominance of the sympathetic branch. This predominance is more marked in symptomatic patients.     

Influence of age and gender on autonomic regulation of heart

Heart rate variability (HRV) is a non-invasive method to measure cardiac autonomic function. Impairments in HRV have been proposed as independent risk factor for increased cardiac mortality and morbidity. Cardio protective phenomenon in females has been hypothesized to be due to differential autonomic tone. Age related loss of vagal control has been reported as predisposing factor for the development of cardiovascular disease. In this study we assessed effect of age and gender on autonomic regulation of heart in healthy volunteers. HRV data of 189 subjects (114 males and 75 females) were analyzed in time and frequency domains using customized program. Artifact free 5 min electrocardiogram segment was used for analysis. It was ensured that none of the subject had medical illness such as diabetes, hypertension, thyroid disorders, cardiac disorders, diseases potentially related with autonomic neuropathy and major psychiatric illness by careful history and clinical examination. HRV recordings were done under standard laboratory condition. On correlation analysis SDNN, RMSSD, total power negatively correlated with age suggesting reduced autonomic regulation of heart with increase in age (SDNN: r = ?0.444, p < 0.01; RMSSD: r = ?0.552, p < 0.01; total power: r = ?0.474, p < 0.01); similarly High frequency power (HF.nu) negatively correlated with age (r = ?0.167, p = 0.02), denoting loss of vagal tone with aging. LF/HF ratio correlated positively with age (r = 0.19, p < 0.01) suggesting a relative increase of sympathetic activity with increase in age. On multiple regression analysis to control for effect of age and heart rate while comparing males and females, LF.nu showed significant reduction suggesting lower sympathetic tone in females (β = ?6.64; p < 0.01) and HF.nu showed increase at trend level (β = 4.47; p = 0.053). In conclusion, there is overall reduction in autonomic control of heart with increase in the age. Sympathetic tone predominates and vagal tone diminishes with aging process. Females showed greater vagal tone than male. This differential autonomic tone indicate age, gender related predisposition to cardiovascular disease.     

Heart rate variability after acute traumatic brain injury in children

OBJECTIVE: To evaluate heart rate variability (HRV) by power spectral analysis of heart rate and its relationship to intracranial pressure (ICP), cerebral perfusion pressure (CPP), and outcomes in children with acute traumatic head injury. DESIGN: Prospective, case series. SETTING: Pediatric intensive care unit in a level II trauma center/children's hospital. SUBJECTS: Fifteen critically ill children with documented acute traumatic brain injury and four control subjects. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The normalized total power from 0.04 to 0.15 Hz was used to quantify low-frequency HRV and from 0.15 to 0.40 Hz to quantify high-frequency HRV. The ratio of low- to high-frequency (LF/HF) power was used as a measure of sympathetic modulation of heart rate. The power spectral data from the 5-min samples were averaged over each hour of data collection, and an hourly LF/HF ratio was obtained based on a 60-min electrocardiogram collection (twelve 5-min segments). The daily mean LF/HF ratio was calculated from the hourly LF/HF measurements. We found no linear correlation between the LF/HF ratio and either ICP or CPP (p = NS). There was a significant decrease in the LF/HF ratio when the intracranial pressure was >30 mm Hg (p < .001) or the cerebral perfusion pressure was <40 mm Hg (p < .001). Children with a Glasgow Coma Scale score of 3-4 had a lower LF/HF ratio compared with those who had a Glasgow Coma Scale score of 5-8 (p < .005). Patients who progressed to brain death had a markedly lower LF/HF ratio (p < .001), with a significant decrease after the first 4 hrs of hospitalization. Patients with more favorable outcomes had significantly higher LF/HF ratios. CONCLUSIONS: Our findings suggest that an ICP of >30 mm Hg or a CPP of <40 mm Hg may be associated with marked autonomic dysfunction and poor outcome. We speculate that HRV power spectral analysis may be a useful adjunct in determining the severity of neurologic insult and the prognosis for recovery in children. The LF/HF ratio may be helpful not only in identifying those patients who will progress to brain death but also in predicting which patients will have favorable outcomes.     

Depressed heart rate variability is associated with high IL-6 blood level and decline in the blood pressure in septic patients

Depressed heart rate variability (HRV) in septic patients is known to be associated with poor outcome. However, neither etiology of depression of HRV nor its clinical significance has been clearly determined. Because hypercytokinemia plays an important role in sepsis, we investigated the relationships between depressed HRV and IL-6 blood level. The subjects of this study were 45 septic patients treated in our intensive care unit. IL-6 blood level upon admission exhibited significant negative correlations with two HRV indices, low-frequency power (LF) (r = -0.76; P < 0.01) and high-frequency power (HF) (r = -0.53; P < 0.01). Multivariate analysis revealed strong correlations between IL-6 blood level and LF (P = 0.01) and HF (P = 0.01), respectively, even when the effects of patient background factors and therapeutic intervention were taken into account. Among the patients who developed septic shock, a high IL-6 blood level and a low LF were observed in both the survivor and nonsurvivor groups on the day of admission. The HF was lower than normal at the same time points in both groups. However, the HF was significantly higher in the nonsurvivor group than in the survivor group. By the time of discharge from the intensive care unit, both IL-6 blood level and HRV indices had become significantly closer to the normal ranges in the survivor group, but not in the nonsurvivor group. A significant negative correlation was observed between LF upon admission and percent decline in blood pressure (r = -0.76, P < 0.01). These findings indicate that reduction in HRV indices is associated with hypercytokinemia, indicating that the autonomic nervous system and the inflammatory response mediated by the cytokine network affect each other. These results also suggest that depression of HRV is closely related to rapid changes in blood pressure. Thus, heart rate variability indices are associated with both the severity and poor outcome of sepsis.     

Evaluation of cardiac autonomic function by various indices in patients with primary premature ovarian failure

Background

The association between premature ovarian failure (POF) and cardiovascular diseases (CVD) was investigated previously, but none of the studies have looked at cardiac autonomic functions in these patients. In this study, we aimed to evaluate cardiac autonomic functions in patients with POF.

Methods

We enrolled 26 female patients (mean age 37.5?±?10.1?years) with primary POF and 31 healthy subjects (mean age 37.5?±?9.0?years). All participants underwent 24-h Holter recording. Heart rate recovery (HRR) indices were calculated by subtracting 1st-, 2nd- and 3rd-min heart rates from maximal heart rate. Heart rate variability (HRV) and heart rate turbulence (HRT) parameters were analyzed in all patients.

Results

Both groups were similar with regard to age, gender, body mass index and left ventricular ejection fraction. Mean HRR1 (p?=?0.018), HRR2 (p?=?0.021) and HRR3 (p?=?0.027) values were significantly higher in the control group. When HRV considered SDNN, SDANN, RMSSD, PNN50 and HF were significantly decreased in patients with POF compared to healthy controls, but LF and LF/HF were significantly higher in POF patients. Both HRT onset and slope were more abnormal in POF patients. Also, there was a significant correlation between HRR, HRV and HRT parameters and FSH, LH and estradiol levels.

Conclusion

Our study results suggest that cardiac autonomic function is impaired in patients with POF despite the absence of overt cardiac involvement and symptoms. Further studies are needed to elucidate the prognostic significance and clinical implications of impaired autonomic functions in patients with POF.