Clinical implications of present physiological understanding of HRV components

Autonomic nervous system assessment using heart rate variability

The role of the autonomic nervous system in the onset of supraventricular and ventricular arrhythmias is well established. It can be analysed by the spontaneous behaviour of the heart rate with ambulatory ECG recordings, through heart rate variability measurements. Input of heart rate variability parameters into artificial intelligence models to make predictions regarding the detection or forecast of rhythm disorders is becoming routine and neuromodulation techniques are now increasingly used for their treatment. All this warrants a reappraisal of the use of heart rate variability for autonomic nervous system assessment.Measurements performed over long periods such as 24H-variance, total power, deceleration capacity, and turbulence are suitable for estimating the individual basal autonomic status. Spectral measurements performed over short periods provide information on the dynamics of systems that disrupt this basal balance and may be part of the triggers of arrhythmias, as well as premature atrial or ventricular beats. All heart rate variability measurements essentially reflect the modulations of the parasympathetic nervous system which are superimposed on the impulses of the adrenergic system. Although heart rate variability parameters have been shown to be useful for risk stratification in patients with myocardial infarction and patients with heart failure, they are not part of the criteria for prophylactic implantation of an intracardiac defibrillator, because of their high variability and the improved treatment of myocardial infarction. Graphical methods such as Poincaré plots allow quick screening of atrial fibrillation and are set to play an important role in the e-cardiology networks. Although mathematical and computational techniques allow manipulation of the ECG signal to extract information and permit their use in predictive models for individual cardiac risk stratification, their explicability remains difficult and making inferences about the activity of the ANS from these models must remain cautious.

Cardiorespiratory function, resting metabolic rate and heart rate variability in coal miners exposed to hypobaric hypoxia in highland workplace

Background

Owing to intermittent/acute exposure to hypobaric hypoxia, highland miners may often suffer, the physiological characteristics between highland and lowland miners, however, are rarely reported. The objective of this study was to compare the physiological characteristics of coal miners working at disparate altitudes.

Methods

Twenty-three male coal mining workers acclimating to high altitude for 30 ± 6 days in Tibet (highland group; approx. 4500 m above sea level; 628.39 millibar), and 22 male coal mining workers in Hebei (lowland group; less than 100 m above sea level; 1021.82 millibar) were recruited. Tests were conducted to compare ventilatory parameters, circulation parameters, resting metabolic rate (RMR), and heart rate variability (HRV) indices between the two groups in resting state.

Results

Ventilation volume per minute (VE) of the highland group was markedly raised compared to that of the lowland group (11.70 ± 1.57 vs. 8.94 ± 1.97 L/min, p = 0.000). In the meanwhile, O2 intake per heart beat (VO2/HR) was strikingly decreased (3.54 ± 0.54 vs. 4.36 ± 0.69 ml/beat, p = 0.000). Resting metabolic rate relevant to body surface area (RMR/BSA) was found no significant difference between the two groups. Evident reduction in standard deviation of NN intervals (SDNN) and remarkable increase in ratio of low- and high- frequency bands (LF/HF) were manifest in highland miners compared to that of lowland ones (110.82 ± 33.34 vs. 141.44 ± 40.38, p = 0.008 and 858.86 ± 699.24 vs. 371.33 ± 171.46, p = 0.003; respectively).

Conclusions

These results implicate that long-term intermittent exposure to high altitude can lead miners to an intensified respiration, a compromised circulation and a profound sympathetic-parasympathetic imbalance, whereas the RMR in highland miners does not distinctly decline.

Heart Rate Variability Can Detect Blunt Traumatic Brain Injury Within the First Hour

INTRODUCTION

In patients with multi-organ system trauma, the diagnosis of coinciding traumatic brain injury can be difficult due to injuries from the hemorrhagic shock that confound clinical and radiographic signs of traumatic brain injury. In this study, a novel technique using heart rate variability was developed in a porcine model to detect traumatic brain injury early in the setting of hemorrhagic shock without the need for radiographic imaging or clinical exam.

METHODS

A porcine model of hemorrhagic shock was used with an arm of swine receiving hemorrhagic shock alone and hemorrhagic shock with traumatic brain injury. High-resolution heart rate frequencies were collected at different time intervals using waveforms based on voltage delivered from the heart rate monitor. Waveforms were analyzed to assess statistically significant differences between heart rate variability parameters in those with hemorrhagic shock and traumatic brain injury versus those with only hemorrhagic shock. Stochastic analysis was used to assess the validity of results and create a model by machine learning to better assess the presence of traumatic brain injury.

RESULTS

Significant differences were found in several heart rate variability parameters between the two groups. Additionally, significant differences in heart rate variability parameters were found in swine within 1 hour of inducing hemorrhage in those with traumatic brain injury versus those without. These results were confirmed with stochastic analysis and machine learning was used to generate a model which determined the presence of traumatic brain injury in the setting of hemorrhage shock with 91.6% accuracy.

CONCLUSIONS

 Heart rate variability represents a promising diagnostic tool to aid in the diagnosis of traumatic brain injury within 1 hour of injury.

Research on the Application of the Dynamic Assisted Sleep Light to Smart Mobile Devices

With the rapid development of science and technology, social competition becomes more and more fierce, and work pressure becomes more and more intense. The problem of sleep has become a disease of modern civilization, and in order to alleviate sleep problems and improve sleep quality, related research methods are constantly updated, and there are more and more ways to address these problems. In this paper, we propose a dynamic assisted sleep light that adjusts the color temperature, illuminance, and frequency of change by controlling the backlight of the smart mobile device, so that the user experiences an improved quality of sleep. In this study, the methods of subjective questionnaire survey and non-subjective physiological parameter measurement were adopted for analysis. The results showed that the continuous use of the light source could continuously enhance the user’s delta energy during sleep and promote the improvement of sleep quality.

Review of Perioperative Music Medicine: Mechanisms of Pain and Stress Reduction Around Surgery

Clinical-experimental considerations and an approach to understanding the autonomic basis of improved surgical outcomes using Perioperative Music Medicine (PMM) are reviewed. Combined surgical, psycho-physiological, and experimental perspectives on Music Medicine (MM) and its relationship to autonomic nervous system (ANS) function are discussed. Considerations are given to the inter-related perioperative effects of MM on ANS, pain, and underlying vagal and other neural circuits involved in emotional regulation and dysregulation. Many surgical procedures are associated with significant pain, which is routinely treated with post-operative opioid medications, which cause detrimental side effects and delay recovery. Surgical trauma shifts the sympathetic ANS to a sustained activation impairing physiological homeostasis and causing psychological stress, as well as metabolic and immune dysfunction that contribute to postoperative mortality and morbidity. In this article, we propose a plan to operationalize the study of mechanisms mediating the effects of MM in perioperative settings of orthopedic surgery. These studies will be critical for the implementation of PMM as a routine clinical practice and to determine the potential limitations of MM in specific cohorts of patients and how to improve the treatment.

Bilevel positive airway pressure improves the autonomic balance in the postoperative period following cardiac surgery: a randomized trial

ABSTRACT The use of bilevel positive airway pressure (BiPAP) has repercussions on cardiorespiratory outcomes. However, the literature still lacks analyses of the postoperative influence of BiPAP on the modulation of the autonomic nervous system after cardiac surgery. This study aimed to evaluate the effects of BiPAP on peripheral oxygen saturation, vital signs, and autonomic balance during hospitalization after cardiac surgery. This randomized controlled trial evaluated 36 patients before and after surgery. The BiPAP group was treated in two 20-minute daily sessions of routine physical therapy since 18 hours after surgery until discharge. The control group received routine physical therapy during the same period. Our primary outcome was peripheral oxygen saturation. Secondary outcomes were vital signs and autonomic balance evaluated by heart rate variability. We observed that peripheral oxygen saturation and blood pressure were unaffected at hospital discharge. Both groups showed a similar increase in heart and respiratory rates. The BiPAP group showed a reduction of the low sympathetic frequency component in −27.1 n.u. (95% CI: −39 to −15.2), increase of high parasympathetic frequency in 27.1 n.u. (95% CI: 15.2 to 39), and an improvement to the LF/HF ratio in −2.5 (95% CI: −3.8 to −1.2), when compared to the control group. BiPAP attenuated sympathetic activity and improved vagal modulation and autonomic balance at hospital discharge. These findings evidence that BiPAP enables more efficient autonomic mechanisms during hospitalization after cardiac surgery.

The Association Between Heart Rate Variability and 90-Day Prognosis in Patients With Transient Ischemic Attack and Minor Stroke

Background: Low heart rate variability (HRV) is known to be associated with increased all-cause, cardiovascular, and cerebrovascular mortality but its association with clinical outcomes in patients with transient ischemic attack (TIA) or minor stroke is unclear.

Methods: We selected TIA and minor stroke patients from a prospective registration study. From each continuous electrocardiograph (ECG) record, each QRS complex was detected and normal-to-normal (N-N) intervals were determined. The standard deviation of all N-N intervals (SDNN) and the square root of the mean squared differences of successive N-N intervals (RMSSD) were calculated. Logistic regression analysis and Cox regression analysis were performed to assess the outcomes of patients at 90 days, and the odds and risk ratios (OR/HR) of each index quartile were compared.

Results: Compared with SDNN patients in the lowest quartile, neurological disability was significantly reduced in other quartile groups at 90 days, with significant differences [OR of group Q2 was 0.659; 95% confidence interval (CI), 0.482–0.900; p = 0.0088; OR of group Q3 was 0.662; 95% CI, 0.478–0.916; p = 0.0127; OR of group Q4 was 0.441; 95% CI, 0.305–0.639; p <0.0001]. Compared with the lowest quartile, the recurrence rate of TIA or minor stroke in patients of the two higher quartiles (Q3 and Q4) of SDNN was significantly reduced at 90 days (HR of Q3 group was 0.732; 95% CI, 0.539–0.995; p = 0.0461; HR of Q4 group was 0.528; 95% CI, 0.374–0.745; p = 0.0003).

Conclusions: Based on our findings, autonomic dysfunction is an adverse indicator for neurological function prognosis and stroke recurrence 90 days after TIA or minor stroke.

Acute renal denervation normalizes aortic function and decreases blood pressure in spontaneously hypertensive rats

Mechanisms involved in the acute responses to renal denervation (RDN) have yet to be fully understood. We assessed urinary volume, autonomic control and aorta vascular reactivity after acute RDN. Male normotensive Wistar rats and spontaneously hypertensive rats (SHR) were divided into normotensive + RDN (ND) or sham surgery (NS), and hypertensive + RDN (HD) or sham surgery (HS). Metabolic parameters and hemodynamic measurements were recorded 72h and 4 days after intervention, respectively. Aortic rings were studied 7 days post RDN in an isometric myograph. Concentration–response curves to phenylephrine, sodium nitroprusside and acetylcholine (10^–10–10⁻⁵ M) were performed. Two-way ANOVA was used for group comparisons and differences reported when p < 0.05. Results are presented as mean ± SEM. Urinary volume was 112% higher in HD vs. HS (HS = 14.94 ± 2.5 mL; HD = 31.69 ± 2.2 mL) and remained unchanged in normotensive rats. Systolic BP was lower in HD rats (HS = 201 ± 12 vs. HD = 172 ± 3 mmHg) without changes in normotensive group. HD group showed increased HF and LF modulation (HS = 5.8 ± 0.7 ms²vs. HD = 13.4 ± 1.4 ms²; HS = 3.5 ± 0.7 ms²vs. HD = 10.5 ± 1.7 ms², respectively). RDN normalized vascular reactivity in HD rats and increased phenylephrine response in ND rats. Acute fall in BP induced by RDN is associated with increased urinary volume, which in turn may also have contributed to functional changes of the aorta.

Comparison of nonparametric and parametric methods for time-frequency heart rate variability analysis in a rodent model of cardiovascular disease

The aim of time-varying heart rate variability spectral analysis is to detect and quantify changes in the heart rate variability spectrum components during nonstationary events. Of the methods available, the nonparametric short-time Fourier Transform and parametric time-varying autoregressive modeling are the most commonly employed. The current study (1) compares short-time Fourier Transform and autoregressive modeling methods influence on heart rate variability spectral characteristics over time and during an experimental ozone exposure in mature adult spontaneously hypertensive rats, (2) evaluates the agreement between short-time Fourier Transform and autoregressive modeling method results, and (3) describes the advantages and disadvantages of each method. Although similar trends were detected during ozone exposure, statistical comparisons identified significant differences between short-time Fourier Transform and autoregressive modeling analysis results. Significant differences were observed between methods for LF power (p ≤ 0.014); HF power (p ≤ 0.011); total power (p ≤ 0.027); and normalized HF power (p = 0.05). Furthermore, inconsistencies between exposure-related observations accentuated the lack of agreement between short-time Fourier Transform and autoregressive modeling overall. Thus, the short-time Fourier Transform and autoregressive modeling methods for time-varying heart rate variability analysis could not be considered interchangeable for evaluations with or without interventions that are known to affect cardio-autonomic activity.

Assessment and clinical relevance of the dynamic parameters of ventricular repolarization in patients with grade I left ventricular diastolic dysfunction 1

Imbalance in ventricular repolarization parameters are related to increased risk of severe arrhythmia and sudden cardiac death. There is limited research regarding markers to detect patients at risk in this early stage. We aimed to assess the influence of grade I left ventricular diastolic dysfunction on repolarization parameters in asymptomatic patients. Ambulatory patients with grade I left ventricular diastolic dysfunction were studied and compared with a control group. We assessed the QT dispersion circadian variation, heart rate variability in the time and frequency domains, and dynamics of QT using a 12-lead Holter. In the diastolic dysfunction group, 8 (30%) patients had QT dispersion > 80 ms. One (3.8%) patient presented premature ventricular complex > 10/h. The comparison between the 2 groups showed that the difference between the standard deviation of normal-to-normal intervals and low frequency power in both groups was statistically significant. We therefore conclude that increased parameters of ventricular repolarization and depressed heart rate variability reflect an imbalance in autonomic responses in patients with grade I left ventricular diastolic dysfunction without cardiovascular symptoms, enabling the identification of patients that are at a higher risk for cardiovascular events.

Analysis of Autonomic Modulation in Response to a Session of Aerobic Exercise at Different Intensities in Patients With Moderate and Severe COPD

Despite the many benefits of performing physical exercise in patients with chronic obstructive pulmonary disease (COPD), information on the response of acute cardiac autonomic modulation in subjects with moderate and severe COPD during and after an aerobic exercise session at different intensities is unknown. The aim of this study was to evaluate the response of cardiac autonomic modulation in patients with moderate and severe COPD during and after an aerobic exercise session at different intensities. Twenty-seven patients with COPD, divided into: Moderate Group and Severe Group, underwent an aerobic exercise sessions with intensities equivalent to 60% and 90% of velocity corresponding to peak oxygen consumption. The heart rate variability (HRV) indices were analyzed in the time and frequency domains at the following times: at rest, during exercise, immediately after, and 5, 10, and 15 minutes after exercise. In the comparison analysis between the two groups, no differences were observed in any of the HRV indices at different intensities applied. However, it was observed that the exercise caused autonomic changes when the groups were analyzed separately. Sessions of aerobic exercise influence the autonomic modulation in patients with COPD. However, COPD severity did not influence the autonomic nervous system response to exercise and recovery moments; and there was no difference between the exercise intensities.

Effects of depression and melatonergic antidepressant treatment alone and in combination with sedative-hypnotics on heart rate variability: Implications for cardiovascular risk

OBJECTIVES

To examine heart rate variability (HRV) in unmedicated patients with major depressive disorder (MDD) and its changes after treatment with agomelatine alone and in combination with sedative-hypnotics.

METHODS

We recruited 152 physically healthy, unmedicated patients with MDD and 472 age- and sex-matched healthy volunteers. Frequency-domain measures of HRV were obtained during enrolment for all participants and again for MDD patients after 6 weeks of treatment with agomelatine alone and combining sedative-hypnotics.

RESULTS

Compared to the controls, unmedicated patients exhibited significantly lower mean R-R intervals, low-frequency (LF) HRV, and high-frequency (HF) HRV, but higher LF/HF ratios. Fifty-six and 49 patients successfully completed agomelatine monotherapy and the combination therapy of agomelatine and sedative-hypnotics, respectively. Between-group analyses showed significant treatment-by-group interactions for LF-HRV, HF-HRV and LF/HF ratio. The results showed a significant increase in HF-HRV after agomelatine monotherapy, a significant decrease in LF-HRV and HF-HRV, and a increase in the LF/HF ratio after combination therapy.

CONCLUSIONS

MDD patients had reduced HRV, and the patterns of HRV changes differed between patients treated with agomelatine alone and in combination with sedative-hypnotics. Clinicians should consider HRV effects when adding sedative-hypnotics to agomelatine, which is important for depressed patients who already have decreased cardiac vagal tone.

Esmolol indirectly stimulates vagal nerve activity in endotoxemic pigs

Background

There is an increasing interest in beta-blockade as a therapeutic approach to sepsis following consistent experimental findings of attenuation of inflammation and improved survival with beta1 selective antagonist. However, the mechanism of these beneficial effects remains very uncertain. Thus, this study is aimed at investigating the effects of a beta-1 selective blockade on sympathetic/parasympathetic activity in endotoxin-challenged pigs using heart rate variability. The hypothesis is that an adrenergic blockade could promote parasympathetic activity. Indeed, the increase of parasympathetic activity is a mechanism recently described as beneficial in septic states.

Methods

Fifty-one endotoxin-challenged pigs were studied. After 30 min of endotoxin infusion and 30 min of evolution without intervention, the pigs were randomly assigned the placebo or esmolol treatment and were observed for 200 min. Overall heart rate variability was assessed continuously, in the temporal domain by standard deviation of RR intervals (SDNN, ms),and in the frequency domain by spectral powers of low frequency (LF, ms² × 10³/Hz) and high frequency (HF, ms² × 10³/Hz) bands.

Results

Variations of power in these frequency bands were interpreted as putative markers of sympathetic (LF) and parasympathetic (HF) activity. In LPS treated animals, Esmolol did not increase SDNN, but instead decreased LF and increased HF power.

Conclusion

These spectral modifications associated to a beta-blocker treatment after an endotoxemic challenge are interpreted as a significant decrease of sympathetic activity and an indirect increase of vagal autonomic tone.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0178-1) contains supplementary material, which is available to authorized users.

Assessment of Quadratic Nonlinear Cardiorespiratory Couplings During Tilt-Table Test by Means of Real Wavelet Biphase

OBJECTIVE

In this paper, a method for assessment of quadratic phase coupling (QPC) between respiration and heart rate variability (HRV) is presented.

METHODS

First, a method for QPC detection is proposed named real wavelet biphase (RWB). Then, a method for QPC quantification is proposed based on the normalized wavelet biamplitude (NWB). A simulation study has been conducted to test the reliability of RWB to identify QPC, even in the presence of constant delays between interacting oscillations, and to discriminate it from quadratic phase uncoupling. Significant QPC was assessed based on surrogate data analysis. Then, quadratic cardiorespiratory couplings were studied during a tilt-table test protocol of 17 young healthy subjects.

RESULTS

Simulation study showed that RWB is able to detect even weak QPC with delays in the range of [Formula: see text] s, which are usual in the autonomic nervous system (ANS) control of heart rate. Results from the database revealed a significant reduction ([Formula: see text]) of NWB between respiration and both low and high frequencies of HRV in head-up tilt position compared to early supine.

CONCLUSION

The proposed technique detects and quantifies robustly QPC and is able to track the coupling between respiration and various HRV components during ANS changes.

SIGNIFICANCE

The proposed method can help to assess alternations of nonlinear cardiorespiratory interactions related to ANS dysfunction and physiological regulation of HRV in cardiovascular diseases.

Heart rate variability among women undergoing in vitro fertilization treatment: Its predictive ability for pregnancy

Objective

This study aimed to assess predictive ability of heart rate variability (HRV) for pregnancy outcomes with in vitro fertilization (IVF) treatment.

Research design and method

A total of 180 women with 261 cycles of IVF and 211 embryo transfers (ETs) were analyzed. HRV was measured at four times during IVF treatment: the first date of menstruation, r-HCG (Ovidrel) administration, and before and after ET. Pregnancy indicators included chemical pregnancy, ongoing pregnancy (> 10 weeks), and live birth (pregnancy > 24 weeks). Mixed effect models were applied to identify predictors for IVF pregnancy. The area under the receiver operating characteristic curve (AUC) was used to assess prediction models for pregnancy.

Results

The HRV values increased during IVF treatment and then decreased after ET. The trend of changes in HRV values during IVF treatment was significant among patients with chemical pregnancy (p < 0.01) and those with live birth (p = 0.02). Women without pregnancy had lower HRV compared to those with IVF pregnancy (p < 0.05). With a one unit increase in HRV difference before and after ET, the odds of chemical pregnancy decreased by 18% (odds ratio; OR: 0.82, 95% CI: 0.70–0.97, p < 0.02). With a one year increase in maternal age, the odds decreased by 16% (OR: 0.84, 95% CI: 0.76–0.93, p < 0.01), 25% (OR: 0.75, 95% CI: 0.58–0.93, p = 0.02), and 28% (OR: 0.72, 95% CI: 0.54–0.91, p = 0.01) for chemical pregnancy, ongoing pregnancy, and live birth, respectively. The AUCs were 0.77 (95% CI: 0.70, 0.84), 0.89 (0.79, 0.98), and 0.91(0.83, 0.99) for the prediction models for chemical pregnancy, ongoing pregnancy, and live birth, respectively.

Conclusions

Reduced HRV may be an indicator for low chance of IVF pregnancy. The changes in HRV before and after ET and maternal age might be prognostic predictors of IVF pregnancy.

Diminution of Heart Rate Variability in Bipolar Depression

Autonomic nervous system (ANS) dysregulation in depression is associated with symptoms associated with the ANS. The beat-to-beat pattern of heart rate defined as heart rate variability (HRV) provides a noninvasive portal to ANS function and has been proposed to represent a means of quantifying resting vagal tone. We quantified HRV in bipolar depressed (BDD) patients as a measure of ANS dysregulation seeking to establish HRV as a potential diagnostic and prognostic biomarker for treatment outcome. Forty-seven BDD patients were enrolled. They were randomized to receive either escitalopram-celecoxib or escitalopram-placebo over 8 weeks in a double-blind study design. Thirty-five patients completed the HRV studies. Thirty-six healthy subjects served as controls. HRV was assessed at pretreatment and end of study and compared with that of controls. HRV was quantified and corrected for artifacts using an algorithm that incorporates time and frequency domains to address non-stationarity of the beat-to-beat heart rate pattern. Baseline high frequency-HRV (i.e., respiratory sinus arrhythmia) was lower in BDD patients than controls, although the difference did not reach significance. Baseline low-frequency HRV was significantly lower in BDD patients (ln4.20) than controls (ln = 5.50) (p < 0.01). Baseline heart period was significantly shorter (i.e., faster heart rate) in BDD patients than controls. No significant change in HRV parameters were detected over the course of the study with either treatment. These findings suggest that components of HRV may be diminished in BDD patients.

The relationships of current suicidal ideation with inflammatory markers and heart rate variability in unmedicated patients with major depressive disorder

Studies investigating inflammatory status and autonomic functioning simultaneously in depressed patients with current suicidal ideation (SI) are lacking. We recruited 58 unmedicated depressed patients with current SI but without lifetime history of suicidal behavior, as well as 61 equally depressed patients without lifetime history of SI or suicidal behavior. We measured serum cortisol, high-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), and autonomic functioning evaluated by frequency-domain measures of heart rate variability (HRV). The intensity of current SI was rated with the Columbia Suicide Severity Rating Scale. Chronic psychological stress was assessed using the Chinese version of the Perceived Stress Scale (PSS). Patients with current SI showed higher hs-CRP and ESR but lower variance (total HRV), low frequency (LF), and high frequency (HF) HRV than those without lifetime history of SI. We found no differences in cortisol levels and PSS scores. The intensity of current SI was negatively correlated with variance, LF, and HF but positively correlated with hs-CRP. Our results help improve the understanding of the relationships among current SI, inflammation, and autonomic functioning in depressed patients. The combined use of inflammatory markers and HRV indices may one day be applied in predicting and monitoring patients' suicide risk.

Analysis of Biosignals During Immersion in Computer Games

The number of computer game users is increasing as computers and various IT devices in connection with the Internet are commonplace in all ages. In this research, in order to find the relevance of behavioral activity and its associated biosignal, biosignal changes before and after as well as during computer games were measured and analyzed for 31 subjects. For this purpose, a device to measure electrocardiogram, photoplethysmogram and skin temperature was developed such that the effect of motion artifacts could be minimized. The device was made wearable for convenient measurement. The game selected for the experiments was League of Legends™. Analysis on the pulse transit time, heart rate variability and skin temperature showed increased sympathetic nerve activities during computer game, while the parasympathetic nerves became less active. Interestingly, the sympathetic predominance group showed less change in the heart rate variability as compared to the normal group. The results can be valuable for studying internet gaming disorder.

Automatic Classification of Sedation Levels in ICU Patients Using Heart Rate Variability

OBJECTIVE

To explore the potential value of heart rate variability features for automated monitoring of sedation levels in mechanically ventilated ICU patients.

DESIGN

Multicenter, pilot study.

SETTING

Several ICUs at Massachusetts General Hospital, Boston, MA.

PATIENTS

Electrocardiogram recordings from 40 mechanically ventilated adult patients receiving sedatives in an ICU setting were used to develop and test the proposed automated system.

MEASUREMENTS AND MAIN RESULTS

Richmond Agitation-Sedation Scale scores were acquired prospectively to assess patient sedation levels and were used as ground truth. Richmond Agitation-Sedation Scale scores were grouped into four levels, denoted "unarousable" (Richmond Agitation- Sedation Scale = -5, -4), "sedated" (-3, -2, -1), "awake" (0), "agitated" (+1, +2, +3, +4). A multiclass support vector machine algorithm was used for classification. Classifier training and performance evaluations were carried out using leave-oneout cross validation. An overall accuracy of 69% was achieved for discriminating between the four levels of sedation. The proposed system was able to reliably discriminate (accuracy = 79%) between sedated (Richmond Agitation-Sedation Scale < 0) and nonsedated states (Richmond Agitation-Sedation Scale > 0).

CONCLUSIONS

With further refinement, the methodology reported herein could lead to a fully automated system for depth of sedation monitoring. By enabling monitoring to be continuous, such technology may help clinical staff to monitor sedation levels more effectively and to reduce complications related to over- and undersedation.

Kudiezi injection mitigates myocardial injury induced by acute cerebral ischemia in rats

Background

Kudiezi (KDZ) injection is commonly used in traditional Chinese medicine as treatment for cerebral infarction and angina pectoris. The present study investigated the therapeutic effects of KDZ injection on myocardial injury induced by acute cerebral ischemia and the possibly protective mechanisms.

Methods

Rats were divided into three groups: sham, 6h-ischemia, and KDZ treatment (KDZ). The neurological deficits were determined by the Garcia score. The cerebral infarct volume was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining, and brain water content was also evaluated. Serum creatinine kinase (CK), lactate dehydrogenase (LDH), and creatine kinase-myocardial band (CK-MB) activity, myocardial tissue malondialdehyde (MDA) levels, L-Glutathione (GSH) levels, and superoxide dismutase (SOD) activity as well as mitochondrial cytochrome c oxidase (COX) activity were determined. Mitochondrial COX I and COX III mRNA expressions of myocardial tissues were measured by RT-PCR.

Results

Impaired neurological function and brain edema were observed in the 6h-ischemia group. TTC staining showed that the 6h-ischemia group had larger infarct zones than the sham group. Myocardial ischemic changes (widened myocardial cell gap, cracks, and obvious edema) were detected in the 6h-ischemia group compared with the sham group, with elevated serum CK-MB activity and CK and LDH levels. Electrocardiography showed lower medium frequency (MF) and high frequency (HF) in the 6h-ischemia group compared with the sham group. In myocardial tissue, COX activity was elevated in the 6h-ischemia compared with the sham group, while SOD, GSH, and MDA levels, and COX I and COX III mRNA expressions remained unchanged. KDZ injection decreased neurological impairment, brain edema, gaps between cells, and infarct size. Compared with the 6h-ischemia group, it reduced serum CK-MB activity and CK and LDH levels, and MDA levels in myocardial tissue. KDZ significantly increased GSH levels, SOD activity, and mitochondria COX activity and the expression of COX I and COX III mRNA in myocardial tissue compared with the sham group.

Conclusion

KDZ injection had a protective effect against cerebral ischemia in rats. KDZ injection could also alleviate myocardial injury after acute cerebral ischemia in rats. The possible mechanisms involve the regulation of the oxidative stress/antioxidant capacity after cerebral ischemia.

Heart Rate Variability (HRV) Analysis: A Methodology for Organizational Neuroscience

Recently, the application of neuroscience methods and findings to the study of organizational phenomena has gained significant interest and converged in the emerging field of organizational neuroscience. Yet, this body of research has principally focused on the brain, often overlooking fuller analysis of the activities of the human nervous system and associated methods available to assess them. In this article, we aim to narrow this gap by reviewing heart rate variability (HRV) analysis, which is that set of methods assessing beat-to-beat changes in the heart rhythm over time, used to draw inference on the outflow of the autonomic nervous system (ANS). In addition to anatomo-physiological and detailed methodological considerations, we discuss related theoretical, ethical, and practical implications. Overall, we argue that this methodology offers the opportunity not only to inform on a wealth of constructs relevant for management inquiries but also to advance the overarching organizational neuroscience research agenda and its ecological validity.

Over-expression of V1A receptors in PVN modulates autonomic cardiovascular control

The hypothalamic paraventricular nucleus (PVN) is a key integrative site for the neuroendocrine control of the circulation and of the stress response. It is also a major source of the neuropeptide hormone vasopressin (VP), and co-expresses V1a receptors (V1aR). We thus sought to investigate the role of V1aR in PVN in cardiovascular control in response to stress. Experiments were performed in male Wistar rats equipped with radiotelemetric device. The right PVN was transfected with adenoviral vectors (Ads) engineered to over-express V1aR along with an enhanced green fluorescent protein (eGFP) tag. Control groups were PVN transfected with Ads expressing eGFP alone, or wild-type rats (Wt). Rats were recorded with and without selective blockade of V1aR (V1aRX) in PVN under both baseline and stressed conditions. Blood pressure (BP), heart rate (HR), their short-term variabilities, and baroreflex sensitivity (BRS) were evaluated using spectral analysis and the sequence method, respectively. Under baseline physiological conditions,V1aR rats exhibited reduced BRS and a marked increase of BP and HR variability during exposure to stress. These effects were all prevented by V1aRX pretreatment. In Wt rats, V1aRX did not modify cardiovascular parameters under baseline conditions, and prevented BP variability increase by stress. However, V1aRX pretreatment did not modify baroreflex desensitization by stress in either rat strain. It follows that increased expression of V1aR in PVN influences autonomic cardiovascular regulation and demarcates vulnerability to stress. We thus suggest a possible role of hypothalamic V1aR in cardiovascular pathology.

Correlation between health-related quality of life in the physical domain and heart rate variability in asymptomatic adults

Background

Reduced health-related quality of life in the physical domain (HRQOL_physical) has been reported to increase risks for cardiovascular disease (CVD); however, the mechanism underlying this phenomenon is still unclear. The autonomic nervous system (ANS) that connects the body and mind is a biologically plausible candidate to investigate this mechanism. The aim of our study is to examine whether the HRQOL_physical independently contributes to heart rate variability (HRV), which reflects ANS activity.

Methods

We recruited 329 physically and mentally healthy adults. All participants completed Beck Anxiety Inventory, Beck Depression Inventory and World Health Organization Questionnaire on Quality of Life: Short Form-Taiwanese version (WHOQOL-BREF). They were divided into groups of individuals having high or low scores of HRQOL_physical as discriminated by the quartile value of WHOQOL-BREF. We obtained the time and frequency-domain indices of HRV, namely variance (total HRV), the low-frequency power (LF; 0.05–0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15–0.40 Hz), which reflects cardiac parasympathetic activity, and the LF/HF ratio.

Results

There was an independent contribution of HRQOL_physical to explaining the variance in HRV after excluding potential confounding factors (gender, age, physical activity, alcohol use, depression and anxiety). Compared with the participants with high levels of HRQOL_physical, those with low levels of HRQOL_physical displayed significant reductions in variance and LF.

Conclusions

This study highlights the independent role of low HRQOL_physical in contributing to the reduced HRV in healthy adults and points to a potential underlying mechanism for HRQOL_physical to confer increased risks for CVD.

Target organ damage in primary hypertensive patients: role of the morning heart rate surge

BACKGROUND

The morning heart rate surge (MHRS) and morning blood pressure surge (MBPS) may be responsible for the high prevalence of cardiovascular events during the morning period. The clinical significance of the MBPS has been well established, but that of the MHRS remains unclear. Thus, we evaluated the association between the MHRS and target organ damage (TOD).

METHODS

A cross-sectional study of 580 hypertensive patients was performed. MHRS and heart rate variability (HRV) were analyzed by 24 h electrocardiogram. TOD was assessed by estimated glomerular filtration rate, carotid intima-media thickness (IMT), and left ventricular mass index.

RESULTS

The prevalence of TOD tended to decrease with sleep-trough MHRS (first to fourth quartiles: 71%, 70.3%, 58.6%, and 52.7%, respectively) or prewaking MHRS quartiles (first to fourth quartiles: 65.3%, 73.6%, 61.4%, and 54.2%, respectively), whereas the opposite trend was observed for standard deviation of all normal NN intervals (SDNN). Moreover, sleep-trough MHRS, prewaking MHRS, SDNN, and SDNN index were significantly lower in patients with TOD than in those without TOD. According to four logistic regression models, the associations of prewaking MHRS, SDNN, and SDNN index with TOD were lost after adjustment for age and BP. Patients in the first (≤11.125 bpm) and second sleep-trough MHRS quartiles (11.125-15.75 bpm) had a 1.95-2.06-fold increased risk of TOD compared with those in the fourth quartile (p < 0.05).

CONCLUSION

A blunted sleep-trough MHRS, which may serve as a surrogate marker for autonomic imbalance, was independently associated with TOD in primary hypertensive patients.

Linking an Anxiety-Related Personality Trait to Cardiac Autonomic Regulation in Well-Defined Healthy Adults: Harm Avoidance and Resting Heart Rate Variability

OBJECTIVE

Anxiety trait, anxiety and depression states have all been reported to increase risks for cardiovascular disease (CVD), possibly through altering cardiac autonomic regulation. Our aim was to investigate whether the relationship between harm avoidance (HA, an anxiety-related personality trait) and cardiac autonomic regulation is independent of anxiety and depression states in healthy adults.

METHODS

We recruited 535 physically and mentally healthy volunteers. Participants completed the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Tri-dimensional Personality Questionnaire. Participants were divided into high or low HA groups as discriminated by the quartile value. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV). We obtained the time and frequency-domain indices of HRV including variance (total HRV), the low-frequency power (LF; 0.05-0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15-0.40 Hz), which reflects cardiac parasympathetic activity, as well as the LF/HF ratio.

RESULTS

The BDI and HA scores showed associations with HRV parameters. After adjustment for the BDI scores and other control variables, HA is still associated with reduced variance, LF and HF power. Compared with the participants with low HA, those with high HA displayed significant reductions in variance, LF and HF power and a significant increase in their LF/HF ratio.

CONCLUSION

This study highlights the independent role of HA in contributing to decreased autonomic cardiac regulation in healthy adults and provides a potential underlying mechanism for anxiety trait to confer increased risk for CVD.

N-Terminal Pro-B-Type Natriuretic Peptide Levels Inversely Correlated With Heart Rate Variability in Patients With Unstable Angina Pectoris

We explored the relationships between heart rate variability (HRV) and levels of N-terminal Pro-B-type natriuretic peptide (NT-proBNP) in patients with unstable angina pectoris (UA).A total of 90 consecutive patients admitted < 48 hours for UA were included. Serum levels of NT-proBNP were measured from blood samples. The cohort was divided into tertiles according to NT-proBNP levels. HRV parameters including SDNN, RMSSD, LF, HF, TP, and VLF were assessed by 24-hour Holter ECG monitoring.The median (IQR) NT-proBNP level was 177.02 (64.76, 740.70) pg/mL. Patients with SDNN < 100 ms had higher levels of NT-proBNP than those with SDNN > 100 ms (P = 0.003). With increasing levels of NT-proBNP, both the 24hour monitoring HRV and night-monitoring HRV showed that SDNN and VLF gradually decreased (P < 0.01), and patients in the NT-proBNP lowest tertile group had higher LF values than the other two groups (P < 0.05); however, no difference was found in RMSSD, HF, and TP. During the daytime, the LF, VLF, and TP values were lower in the NTproBNP highest group compared with the lowest tertile group (P < 0.05). NT-proBNP levels correlated negatively with SDNN (r = -0.314, P = 0.003) and VLF (r = -0.397, P < 0.001) but not with other HRV parameters. Multiple regression analysis showed that serum levels of NT-proBNP remained predictive of SDNN (β = -0.060, P = 0.001) and VLF (β = -0.145, P < 0.001), even after adjustment for confounders.Our study showed that the elevated serum levels of NT-proBNP predict reduced HRV parameters, and the increased NT-proBNP levels combined with decreased HRV represent the degree of neurohormonal dysfunction and may be better prognostic predictors for risk stratification in UA patients.

Distinguishing bipolar II depression from unipolar major depressive disorder: Differences in heart rate variability

OBJECTIVES

Bipolar II (BPII) depression is commonly misdiagnosed as unipolar depression (UD); however, an objective and reliable tool to differentiate between these disorders is lacking. Whether cardiac autonomic function can be used as a biomarker to distinguish BPII from UD is unknown.

METHODS

We recruited 116 and 591 physically healthy patients with BPII depression and UD, respectively, and 421 healthy volunteers aged 20-65 years. Interviewer and self-reported measures of depression/anxiety severity were obtained. Cardiac autonomic function was evaluated by heart rate variability (HRV) and frequency-domain indices of HRV.

RESULTS

Patients with BPII depression exhibited significantly lower mean R-R intervals, variance (total HRV), low frequency (LF)-HRV, and high frequency (HF)-HRV but higher LF/HF ratio compared to those with UD. The significant differences remained after adjusting for age. Compared to the controls, the patients with BPII depression showed cardiac sympathetic excitation with reciprocal vagal impairment, whereas the UD patients showed only vagal impairment. Depression severity independently contributed to decreased HRV and vagal tone in both the patients with BPII depression and UD, but increased sympathetic tone only in those with BPII depression.

CONCLUSIONS

HRV may aid in the differential diagnosis of BPII depression and UD as an adjunct to diagnostic interviews.

Association of glucose homeostasis measures with heart rate variability among Hispanic/Latino adults without diabetes: the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

BACKGROUND

Reduced heart rate variability (HRV), a measure of cardiac autonomic function, is associated with an increased risk of cardiovascular disease (CVD) and mortality. Glucose homeostasis measures are associated with reduced cardiac autonomic function among those with diabetes, but inconsistent associations have been reported among those without diabetes. This study aimed to examine the association of glucose homeostasis measures with cardiac autonomic function among diverse Hispanic/Latino adults without diabetes.

METHODS

The Hispanic community Health Study/Study of Latinos (HCHS/SOL; 2008-2011) used two-stage area probability sampling of households to enroll 16,415 self-identified Hispanics/Latinos aged 18-74 years from four USA communities. Resting, standard 12-lead electrocardiogram recordings were used to estimate the following ultrashort-term measures of HRV: RR interval (RR), standard deviation of all normal to normal RR (SDNN) and root mean square of successive differences in RR intervals (RMSSD). Multivariable regression analysis was used to estimate associations between glucose homeostasis measures with HRV using data from 11,994 adults without diabetes (mean age 39 years; 52 % women).

RESULTS

Higher fasting glucose was associated with lower RR, SDNN, and RMSSD. Fasting insulin and the homeostasis model assessment of insulin resistance was negatively associated with RR, SDNN, and RMSSD, and the association was stronger among men compared with women. RMSSD was, on average, 26 % lower in men with higher fasting insulin and 29 % lower in men with lower insulin resistance; for women, the corresponding estimates were smaller at 4 and 9 %, respectively. Higher glycated hemoglobin was associated with lower RR, SDNN, and RMSSD in those with abdominal adiposity, defined by sex-specific cut-points for waist circumference, after adjusting for demographics and medication use. There were no associations between glycated hemoglobin and HRV measures among those without abdominal adiposity.

CONCLUSIONS

Impairment in glucose homeostasis was associated with lower HRV in Hispanic/Latino adults without diabetes, most prominently in men and individuals with abdominal adiposity. These results suggest that reduced cardiac autonomic function is associated with metabolic impairments before onset of overt diabetes in certain subgroups, offering clues for the pathophysiologic processes involved as well as opportunity for identification of those at high risk before autonomic control is manifestly impaired.

Heart rate variability in major depressive disorder and after antidepressant treatment with agomelatine and paroxetine: Findings from the Taiwan Study of Depression and Anxiety (TAISDA)

Evidence from previous studies suggests that heart rate variability (HRV) is reduced in major depressive disorder (MDD). However, whether this reduction is attributable to the disorder per se or to medication, since antidepressants may also affect HRV, is still debated. There is a dearth of information regarding the effects of agomelatine, a novel antidepressant, on HRV. Here, we investigated whether HRV is reduced in MDD and compared the effects of agomelatine and paroxetine on HRV. We recruited 618 physically healthy unmedicated patients with MDD and 506 healthy volunteers aged 20-65 years. Frequency-domain measures of resting HRV were obtained at the time of enrollment for all participants. For patients with MDD, these measures were obtained again after 6 weeks of either agomelatine or paroxetine monotherapy. Compared with healthy subjects, unmedicated patients with MDD exhibited significantly lower variance (total HRV), low frequency (LF), and high frequency (HF) HRV, and a higher LF/HF ratio. Depression severity independently contributed to decreased HRV and vagal tone. Fifty-six patients completed the open-label trial (n=29 for agomelatine, n=27 for paroxetine). Between-group analyses showed a significant group-by-time interaction for LF-HRV and HF-HRV, driven by increases in LF-HRV and HF-HRV only after agomelatine treatment. Within the paroxetine-treated group, there were no significant changes in mean R-R intervals or any HRV indices. We therefore concluded that MDD is associated with reduced HRV, which is inversely related to depression severity. Compared with paroxetine, agomelatine has a more vagotonic effect, suggesting greater cardiovascular safety. Clinicians should consider HRV effects while selecting antidepressants especially for depressed patients who already have decreased cardiac vagal tone.

Different Patterns of Heart Rate Variability During Acute Withdrawal in Alcohol Dependent Patients With and Without Comorbid Anxiety and/or Depression

Abstract. The aim of the present study was to examine cardiac autonomic function during acute alcohol withdrawal (AW) in two clinical subgroups with alcohol dependence. To this end we compared 24 patients with pure alcohol dependence (Pure ALC) with 24 alcohol-dependent patients who had comorbid symptoms of anxiety and/or depression (ANX/DEP ALC) on their mean heart rate and several (spectral) measures of heart rate variability (HRV) obtained from the patients when they were withdrawn from alcohol. To elucidate the contribution of anxiety and depression to the cardiac measures we moreover compared these groups to 120 non-comorbid patients with major depressive disorder (MDD), 24 patients with anxiety disorders and 120 matched controls. The Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale (HAM-A) were employed for the clinical symptom ratings. The cardiac measures were found to significantly discriminate among the groups (Hotelling-Lawley F = 3.18, p < .001). Post hoc testing revealed that total HRV (variance in interbeat intervals) was reduced in Pure ALC (p = .033, Cohen’s d = −0.51), ANX/DEP ALC (p < .001, Cohen’s d = −1.33), MDD (p < .001, Cohen’s d = −0.66), and anxiety disorders (p = .002, Cohen’s d = −0.69), relative to controls. When these comparisons were adjusted for smoking history in pack-years, the results were unchanged. The ANX/DEP ALC patients showed significantly greater reduction in total HRV and high frequency (HF)-HRV compared with the Pure ALC patients. Both anxiety and depression moderated the influence of alcohol use and withdrawal on resting HRV. Our results suggest that compared to Pure ALC, ANX/DEP ALC presents a subtype of alcohol dependence with higher vulnerability to reduced HRV during acute AW. Implications for cardiovascular risk are discussed.

Illness severity, trait anxiety, cognitive impairment and heart rate variability in bipolar disorder

Numerous studies have documented a significant association between symptom severity and cognitive functioning in bipolar disorder (BD). These findings advanced speculations about a potential link between the physiological stress associated with illness severity and cognitive dysfunction. To explore this hypothesis, the current study employed heart rate variability (HRV) as a physiological measure that is sensitive to the effects of chronic stress, and a scale of trait anxiety for assessing a psychological condition that is correlated with hyper sympathetic arousal. Analyses indicated that BD patients with High Illness Severity reported more symptoms of trait-anxiety (i.e., State Trait Anxiety Inventory), performed more poorly on a computerized neuropsychological battery (i.e., CNS Vital Signs), and exhibited a more constricted HRV profile (i.e., lower SDNN with elevated LF/HF ratio) than patients with Low Illness Severity. Illness severity was determined by a history of psychosis, illness duration, and number of mood episodes. A third group of healthy controls (n=22) performed better on the neuropsychological battery and exhibited a healthier HRV profile than the BD groups. This study provides preliminary evidence that illness severity and cognitive impairment in BD may be associated with state anxiety and neuro-cardiac alterations that are sensitive to physiological stress.

Leptin, adiponectin, and heart rate variability among police officers

OBJECTIVES

Police officers have a high prevalence of cardiovascular disease (CVD). Reduced heart rate variability (HRV) is known to increase CVD risk. Leptin and adiponectin may be related to CVD health. Therefore, our objective was to investigate the relationship between these variables and HRV.

METHODS

Leptin and adiponectin levels were measured in 388 officers from the Buffalo Cardio-Metabolic Occupational Police Stress study. HRV was assessed according to methods published by the Task Force of the European Society of Cardiology and the North American Society of Pacing Electrophysiology for measurement and analysis of HRV. Mean values of high-frequency (HF) and low-frequency (LF) HRV were compared across tertiles of leptin and adiponectin using analysis of variance and analysis of covariance; trends were assessed using linear regression models.

RESULTS

Leptin, but not adiponectin, was significantly and inversely associated with HRV. Body mass index (BMI) and percent body fat significantly modified the association between leptin and LF (but not HF) HRV. Among officers with BMI < 25 kg/m(2) , leptin was not significantly associated with HRV. However, among officers with BMI ≥ 25 kg/m(2) , leptin was inversely associated with HRV, after adjustment for age, gender, and race/ethnicity; HF HRV, P = 0.019 and LF HRV, P < 0.0001. Similarly, among officers with percent body fat ≥ 25.5%, leptin and LF HRV showed significant, inverse associations (adjusted P = 0.001).

CONCLUSIONS

Leptin levels were inversely associated with LF HRV, especially among officers with increased adiposity. Increased leptin levels may be associated with CVD-related health problems.

Impact of successful treatment of acromegaly on overnight heart rate variability and sleep apnea

BACKGROUND

Successful treatment of acromegaly improves disease-related cardiovascular mortality and morbidity, but its effects on autonomic modulation of the heart rate are unknown.

OBJECTIVES

We documented treatment-induced changes in time-domain heart rate variability, taking into account the confounding effects of obstructive sleep apnea.

PATIENTS AND METHODS

Sixteen consecutive patients (12 males, aged 43 ± 12 y) with newly diagnosed acromegaly underwent overnight (12:00-7:00 am) cardiac Holter recordings coupled with polysomnography. Data were obtained before and 10 ± 6 months after successful treatment of acromegaly.

RESULTS

IGF-1 levels fell from 807 ± 333 to 207 ± 69 μg/L and normalized in all patients. Seven patients (44%) had obstructive sleep apnea (apnea-hypopnea index 33 ± 21/h) at baseline. Treatment had no significant effect on polysomnographic indices. After treatment, increases were noted in the normal-to-normal heart period (NN), SD-NN, the percentage of NN differing from the previous NN by greater than 50 msec, and the root mean square of successive differences in NN (each P < .05). These heart rate variability results were not influenced by the type of treatment, and there was no relationship between changes in NN and changes in the apnea-hypopnea index (P = .58).

CONCLUSION

Early after successful treatment of acromegaly, we observed increased parasympathetic modulation/decreased sympathetic modulation of the nighttime heart rate, an effect that seems unrelated to changes in sleep apnea status. Treatments aimed at normalizing IGF-1 may improve cardiovascular homeostasis through improved cardiac autonomic nervous system modulation.

Arrhythmia risk assessment using heart rate variability parameters in patients with frequent ventricular ectopic beats without structural heart disease

BACKGROUND

Ventricular ectopic beats (VEBs) are usually considered a benign condition that can be managed with conservative measures. Heart rate variability (HRV), which is one of the most important methods for assessing autonomic activity, is a noninvasive, quantitative method of analyzing autonomic effects on the heart. We aimed to investigate the risk of arrhythmia in patients with VEBs and without cardiovascular disease by using HRV parameters.

METHODS

Patients with frequent VEBs (more than 30 times in 1 hour, according to the Lown classification) were identified. Identified patients were evaluated by 24-hour ECG recording. Our study included 43 patients with frequent VEBs and 43 controls.

RESULTS

General characteristics of the study population were similar. The LF (low frequency)/HF (high frequency) ratio was significantly higher in the frequent VEBs group than in the control group (P < 0.001). The rate of paroxysmal atrial fibrillation (PAF) was higher in the frequent VEB group than in the control group (P = 0.003). The number of VEBs was correlated with LF/HF ratio and PAF (r = 0.339, P = 0.001 and r = 0.294, P = 0.006, respectively).

CONCLUSIONS

Our study showed that the sympathetic nervous system is dominant in young patients with VEBs and without significant comorbidities. There is a higher risk of atrial fibrillation in patients with VEBs and they should be monitored closely for atrial fibrillation.

Nonlinear heart rate variability measures under electromagnetic fields produced by GSM cellular phones

This study was designed to assess the nonlinear dynamics of heart rate variability (HRV) during exposure to low-intensity EMFs. Twenty-six healthy young volunteers were subjected to a rest-to-stand protocol to evaluate autonomic nervous system in quiet condition (rest, vagal prevalence) and after a sympathetic activation (stand). The procedure was conducted twice in a double-blind design: once with a genuine EMFs exposure (GSM cellular phone at 900 MHz, 2 W) and once with a sham exposure (at least 24 h apart). During each session, three-lead electrocardiograms were recorded and RR series extracted off-line. The RR series were analyzed by nonlinear deterministic techniques in every phase of the protocol and during the different exposures. The analysis of the data shows there was no statistically significant effect due to GSM exposure on the nonlinear dynamics of HRV.

Modulation of Cardiac Autonomic Dysfunction in Ischemic Stroke following Ayurveda (Indian System of Medicine) Treatment

Objectives. Cardiac autonomic dysfunction in stroke has implications on morbidity and mortality. Ayurveda (Indian system of medicine) describes stroke as pakshaghata. We intended to study the effect of Ayurveda therapies on the cardiac autonomic dysfunction. Methods. Fifty patients of ischemic stroke (middle cerebral artery territory) (mean age 39.26 ± 9.88 years; male 43, female 7) were recruited within one month of ictus. All patients received standard allopathic medications as advised by neurologist. In addition, patients were randomized to receive physiotherapy (Group I) or Ayurveda treatment (Group II) for 14 days. Continuous electrocardiogram and finger arterial pressure were recorded for 15 min before and after treatments and analyzed offline to obtain heart rate and blood pressure variability and baroreflex sensitivity (BRS). Results were analysed by RMANOVA. Results. Patients in Group II showed statistically significant improvement in cardiac autonomic parameters. The standard deviation of normal to normal intervals,and total and low frequency powers were significantly enhanced (F = 8.16, P = 0.007, F = 9.73, P = 0.004, F = 13.51, and P = 0.001, resp.). The BRS too increased following the treatment period (F = 10.129, P = 0.004). Conclusions. The current study is the first to report a positive modulation of cardiac autonomic activity after adjuvant Ayurveda treatment in ischemic stroke. Further long term studies are warranted.

Effect of weight loss on sympatho-vagal balance in subjects with grade-3 obesity: restrictive surgery versus hypocaloric diet

Few and mostly uncontrolled studies indicate that weight loss improves heart rate variability (HRV) in grade-3 obesity. The aim of this study was to compare in grade-3 obesity surgery and hypocaloric diet on clinical and metabolic variables and on autonomic indices of HRV. Twenty-four subjects (body mass index, BMI 45.5 ± 9.13 kg/m(2)) underwent surgery (n = 12, gastric banding, LAGB) or received hypocaloric diet (n = 12, 1,000-1,200 kg/day). Clinical [BMI, systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate] and metabolic variables [glucose, cholesterol, HDL- and LDL-cholesterol, triglycerides, AST and ALT transaminases] and 24-h Holter electrocardiographic-derived HRV parameters [R-R interval, standard deviation of R-R intervals (SDNN); low/high-frequency (LF/HF) ratio, and QT interval] were measured at baseline and after 6 months. The two groups were identical at baseline. BMI (-7.5 ± 3.57 kg/m(2), mean ± SD), glucose (-24.1 ± 26.77 mg/dL), SBP (-16.7 ± 22.19 mmHg) and DBP (-6.2 ± 8.56 mmHg) decreased in LAGB subjects (p < 0.05) and remained unchanged in controls. At 6 months, SDNN increased in LAGB subjects (+25.0 ± 37.19 ms, p < 0.05) and LF/HF ratio diminished (2.9 ± 1.84 vs. 4.9 ± 2.78; p = 0.01), with no change in controls; LF (daytime) and HF (24 h and daytime) increased in LAGB subjects, with no change in controls. Decrease in BMI correlated with SBP and DBP decrease (p < 0.05), and DBP decrease correlated with HR decrease (p < 0.05) and QT shortening (p < 0.05). Weight loss is associated with improvement of glucose metabolism, of blood pressure, and with changes in time and frequency domain parameters of HRV; all these changes indicate recovery of a more physiological autonomic control, with increase in parasympathetic and reduction in sympathetic indices of HRV.

Visual pursuit response in the severe disorder of consciousness: modulation by the central autonomic system and a predictive model

Background

A visual pursuit response is reportedly observed in ~20-30% of subjects in vegetative state (VS/UWS) and predicts better outcome; it is a key marker of evolution into the minimally conscious state (MCS). The probability of observing a positive response, however, has proven variable during the day, with comparable timing of the minima and maxima in VS/UWS and MCS. We verified if measures of sympathetic/parasympathetic balance are possible independent variables on which the occurrence of a pursuit response could depend and be predicted.

Methods

Fourteen subjects in VS/UWS and sixteen in MCS for more than one year were studied. A mirror was used to test the pursuit response for a total 231 useful trials. Non-invasive measures of the sympathetic/parasympathetic functional state (Heart rate variability descriptors nuLF and peakLF) used in the study of responsiveness in VS/UWS and MCS subjects were recorded and processed by descriptive statistics and advanced Support Vector Machine (SVM).

Results

A pursuit response was observed in 33% and 78.2% of subjects in VS or MCS, respectively. Incidence was higher at HRV nuLF values in the 20–60 range and peakLF values at 0.06-0.12 Hz (76.6%) and at nuLF values in the 10–60 range and peakLF values at 0.05-0.10 Hz (80.7%) in the VS and MCS, respectively. The SVM generated model confirmed the results in the training leave one out and 10 fold cross validation tests (81% and 81.4%).

Conclusion

The pursuit response incidence depends to a relevant extent on the sympathetic/parasympathetic balance and autonomic functional state. Extensive monitoring appears advisable.

Cardiac autonomic dysregulation in acute schizophrenia

OBJECTIVE

Altered cardiac autonomic function has been proposed in schizophrenia, but the results are mixed. Therefore, analyses with larger sample sizes and better methodology are needed.

METHODS

To examine whether acute schizophrenia is associated with cardiac autonomic dysfunction, 314 unmedicated patients with acute schizophrenia and 409 healthy volunteers, aged 18-65 years, were recruited for a case-control analysis. The severity of schizophrenia symptoms was assessed with the Positive and Negative Syndrome Scale. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters during the supine-standing-supine test. Frequency-domain indices of HRV were obtained.

RESULTS

Unmedicated patients with acute schizophrenia consistently exhibited reduced mean RR interval and HRV levels in a supine rest and standing position compared with healthy volunteers. The severity of psychopathology, in particular positive symptoms, was negatively correlated with cardiac vagal control.

CONCLUSION

These data suggest that acute schizophrenia is accompanied by cardiac autonomic dysregulation. In view of the higher risk for cardiac complications in these patients, one might also consider the antipsychotic treatment in favour of improving cardiac autonomic modulation. Further studies using larger patient groups and controlled therapeutics may better understand the influence of antipsychotic treatment on cardiac autonomic regulation in schizophrenia.

An inverse correlation between TNF alpha serum levels and heart rate variability in patients with heart failure

BACKGROUND

Recent evidence indicates that chronic heart failure (CHF) is accompanied by both activation of the immune system and autonomic imbalance. There is a growing body of evidence that increased levels of proinflammatory cytokines and other inflammatory markers have important roles as mediators of disease progression and markers of mortality in patients with CHF.

OBJECTIVE

The aim of this study was to investigate connection between autonomic imbalance [obtained by analysis of heart rate variability (HRV)] and activation of the immune system [as measured by serum levels of tumor necrosis factor (TNF)-α] in patients with chronic heart failure.

MATERIALS AND METHODS

This cross-sectional study included 21 patients with CHF and 8 age- and gender-matched healthy control subjects. We assessed HRV by 24-hour electrocardiographic Holter monitoring and measured serum levels of TNF-α using an enzyme-linked immunosorbent assay. Clinical assessment and echocardiography were also performed.

RESULTS

There was an inverse correlation between serum level of TNF-α and a time-domain parameter of HRV - SDNN (r=-0.542, p<0.05). A similar result was found for HRV triangular index, a geometric measure of HRV (r=-0.556; p<0.05). The correlation was stronger for subjects with a diabetes mellitus, females, and TNFA2 allele carriers (an "A" at position -308A). The pNN50, indirect marker of cardiac vagal activity, was not significantly associated with serum concentration of TNF-α.

CONCLUSIONS

In conclusion, the results of the present study indicate that increased serum TNF-α level is significantly associated with reduced HRV indices, suggesting that activation of the immune system in patients with CHF is closely related to autonomic imbalance.

Sex differences in cardiac autonomic regulation and in repolarisation electrocardiography

The review summarises the present knowledge on the sex differences in cardiac autonomic regulations and in related aspects of electrocardiography with particular attention to myocardial repolarisation. Although some of the sex differences are far from fully established, multitude of observations show consistent differences between women and men. Despite more pronounced parasympathetic cardiac regulation, women have higher resting heart rate and lower baroreflex sensitivity. Of the electrocardiographic phenomena, women have longer QT interval duration, repolarisation sequence more synchronised with the inverse of the depolarisation sequence, and likely increased regional heterogeneity of myocardial repolarisation. Studies investigating the relationship of these sex disparities to hormonal differences led frequently to conflicting results. Although sex hormones seem to play a key role by influencing both autonomic tone and electrophysiological properties at the cellular level, neither the truly relevant hormones nor their detailed actions are known. Physiologic usefulness of the described sex differences is also unknown. The review suggests that new studies are needed to advance the understanding of the physiologic mechanisms responsible for these inequalities between women and men and provides key methodological suggestions that need to be followed in future research.

Neuropeptide Y polymorphism increases the risk for asthma in overweight subjects; protection from atherosclerosis in asthmatic subjects--the cardiovascular risk in young Finns study

AIMS

The role of neuropeptide Y (NPY) and its gene polymorphisms in the development of atherosclerosis has become increasingly evident. In asthma, NPY has been shown to be involved as immunomodulator. In this study, we investigated the role of two functional NPY polymorphisms, NPY-Leu7Pro (rs16139) and NPY-399C/T (rs16147) and obesity for the development of asthma as well as atherosclerosis in asthmatic and non-asthmatic subjects. Also, we measured heart rate variability (HRV) and NPY in serum since these might contribute through these polymorphisms to both diseases.

METHODS AND RESULTS

Thousand hundred and seventy six Finnish young adults were genotyped and three groups (G1-G3) were formed based on the observed diplotypes. The NPY-Pro7 allele always co-existed with the NPY-399T allele indicating complete linkage disequilibrium. Here we show that overweight (BMI≥25kg/m2) was associated with 2.5-fold increased risk for asthma in subjects with the NPY-399T allele without NPY-Pro7 allele (G2, n=716). Overweight was also associated with increased atherosclerosis determined by carotid intima media thickness (cIMT), but asthma seemed to be more significant determinant than overweight in determing cIMT having a decreasing effect. NPY concentration in serum was diplotype-driven (G1=792.2(29.5), G2=849.0(18.9), G3=873.9(45.2) pg/ml) and correlated positively with cIMT in the group having NPY-Pro7 allele (G3, n=142). However, the subjects with asthma had a negative NPY-cIMT relationship. Total HRV was increased in asthma and correlated negatively with cIMT irrespective of the NPY genotype.

CONCLUSIONS

Overweight together with the NPY-399T allele without NPY-Pro7 allele was associated with increased risk for asthma. Atherosclerosis was decreased in subjects with asthma depending on the NPY genotype. The results reveal novel insights into the genetics and biology of the relationship of atherosclerosis and asthma.