Heart Rate Variability Analysis Research Articles

Relation between heart rate variability and spectral analysis of electroencephalogram in chronic neuropathic pain patients.

Chronic neuropathic pain (CNP) is a complex condition often arising from neural maladaptation after nerve injury. Understanding CNP complications involves the intricate interplay between brain-heart dynamics, assessed through quantitative electroencephalogram (qEEG) and heart rate variability (HRV). However, insights into their interaction in chronic pain are limited. Resting EEG and simultaneous electrocardiogram (lead II) of the participants were recorded for qEEG and HRV analysis. Correlations between HRV and qEEG parameters were calculated and compared with age, sex, and body mass index (BMI)-matched controls. CNP patients showed reduced HRV and significant increases in qEEG power spectral densities within delta, theta, and beta frequency ranges. A positive correlation was found between low frequency/ high frequency (LF/HF) ratio in HRV analysis and theta, alpha, and beta frequency bands in qEEG among CNP patients. However, no significant correlation was observed between parasympathetic indices and theta, beta bands in qEEG within CNP group, unlike age, sex, and BMI-matched healthy controls. CNP patients display significant HRV reductions and distinctive qEEG patterns. While healthy controls exhibit significant correlations between parasympathetic HRV parameters and qEEG spectral densities, these relationships are diminished or absent in CNP individuals. LF/HF ratio, reflecting sympathovagal balance, correlates significantly with qEEG frequency bands (theta, alpha, beta), illuminating autonomic dysregulation in CNP. These findings emphasize the intricate brain-heart interplay in chronic pain, warranting further exploration.

Using the Hilbert Transform to Evaluate the Effects of Functional Foods on Autonomic Nervous System Activity: A Comparison with the Fast Fourier Transform.

Evaluating the autonomic nervous system (ANS) via heart rate variability (HRV) to investigate the effects of food on human health has attracted attention. However, using a conventional HRV analysis via the fast Fourier transform (FFT), it is difficult to remove artifacts such as body movements and/or abnormal physiological responses (unexpected events) from the HRV analysis results. In this study, an analysis combining bandpass filters and the Hilbert transform was applied to HRV data on functional food intake to compare with FFT analysis. HRV data were obtained from six males by recording electrocardiograms on functional food, γ-aminobutyric acid, intake. HRV indices were calculated by both analysis. In the Hilbert analysis, all HRV indices were obtained for the same number of sampling points as the HRV data. The standard errors of all HRV indices tended to be smaller in the Hilbert analysis than in the FFT analysis. In conclusion, the Hilbert analysis was more suitable than FFT analysis for evaluating ANS via HRV on functional foods intake.

Circadian changes of autonomic function in patients with zoster-associated pain: A heart rate variability analysis.

To investigate the circadian changes of the autonomic function in patients with zoster-associated pain (ZAP). A total of 37 patients with ZAP from April 2022 to October 2022 were enrolled as the observation group, and 37 normal volunteers at the same time were selected as the control group. All participants were required to wear a 24-h Holter, which was used to compare the heart rate variability (HRV) between the two groups. HRV analysis involved time- and frequency-domain parameters. There was no statistically significant difference in general information between two groups. Patients with ZAP had an increased mean heart rate and decreased the standard deviation of normal-to-normal (SDNN) R-R interval, the root mean square of the differences (RMSSD) in successive RR interval, low frequency (LF), and high frequency (HF) compared with control groups in all periods (p<.05). The ratio of LF/HF between two groups had no significant difference (p=.245). SDNN had no significant difference between day and night in the control group (p>.05), whereas SDNN of ZAP patients in night period was reduced than that in day period (p<.001). The level of RMSSD during the day was lower than those at night in the control group (p<.05), whereas no significant difference of RMSSD between two periods was observed in patients with ZAP (p>.05). The results of this study indicated that ZAP contributes to the decline of autonomic nervous system (ANS) function, especially parasympathetic components. The patients with ZAP lost parasympathetic advantage and had a worse ANS during the night.

Facilitating ambulatory heart rate variability analysis using accelerometry-based classifications of body position and self-reported sleep.

OBJECTIVE&#xD;This study aimed to examine differences in heart rate variability (HRV) across accelerometer-derived position, self-reported sleep, and different summary measures (sleep, 24h-HRV) in free-living settings using open-source methodology. &#xD;APPROACH&#xD;HRV is a biomarker of autonomic activity. As it is strongly affected by factors such as physical behaviour, stress, and sleep, ambulatory HRV analysis is challenging. Beat-to-beat heart rate (HR) and accelerometry data were collected using single-lead electrocardiography and trunk- and thigh-worn accelerometers among 160 adults participating in the SCREENS trial. HR files were processed and analysed in the RHRV R package. Start time and duration spent in physical behaviours were extracted, and time and frequency analysis for each episode was executed. Differences in HRV estimates across activities were compared using linear mixed models adjusted for age and sex with subject ID as random effect. Next, repeated-measures Bland-Altman analysis was used to compare 24h RMSSD estimates to HRV during self-reported sleep. Sensitivity analyses evaluated the accuracy of the methodology, and the approach of employing accelerometer-determined episodes to examine activity-independent HRV was described.&#xD;MAIN RESULTS&#xD;HRV was estimated for 31,289 episodes in 160 individuals (53.1% female) at a mean age of 41.4 years. Significant differences in HR and most markers of HRV were found across positions [Mean differences RMSSD: Sitting (Reference) - Standing (-2.63 ms) or Lying (4.53 ms)]. Moreover, ambulatory HRV differed significantly across sleep status, and poor agreement between 24h estimates compared to sleep HRV was detected. Sensitivity analyses confirmed that removing the first and last 30 seconds of accelerometry-determined HR episodes was an accurate strategy to account for orthostatic effects. &#xD;SIGNIFICANCE&#xD;Ambulatory HRV differed significantly across accelerometry-assigned positions and sleep. The proposed approach for free-living HRV analysis may be an effective strategy to remove confounding by physical activity when the aim is to monitor general autonomic stress. &#xD; .

Following your heart: Cardiac autonomic modulation as a feature of decision-making under ambiguity and risk

Decision-making requires a bidirectional flow of information from perception, emotion, and bodily behaviour. Heart rate variability (HRV) provides a non-invasive, cost-effective way to assess this connection. 112 healthy participants completed two established decision tasks under ambiguity and risk. Heart rate was continuously recorded at rest, during, and after task performance. To account for differences in cardiac modulation the sample was stratified by sex. Time, frequency, and non-linear HRV domains were selected to assess vagal modulation and sympatho-vagal balance. Vagally meditated HRV showed a pattern corresponding to a replenishment effect by increasing during decision-making in both tasks compared to rest, and then gradually returning to initial levels during recovery. This effect may indicate successful self-regulation, such as enhanced concentration, or emotional regulation. Regarding decision-making, women and men making disadvantageous decisions under ambiguity had higher vagally mediated HRV than those making advantageous decisions. Consistent with this finding are the results for decisions under risk for women. Contrary, men making disadvantageous decisions under risk, showed lower vagally mediated HRV than those making advantageous decisions. The results suggest that there are sex-specific differences to be investigated in the future. HRV analysis is an effective approach for differentiating somatic characteristics associated with decision-making performance.

0484 Heart Rate Variability and Deep Learning Analysis of Obstructive Sleep Apnea Using ECG from Polysomnography

0484 Heart Rate Variability and Deep Learning Analysis of Obstructive Sleep Apnea Using ECG from Polysomnography

Vagal tone, pain sensitivity and exercise-induced hypoalgesia: The effect of physical activity level.

Vagal activity has analgesic effects that are attributed to exercise-induced hypoalgesia (EIH). High vagal tone and low pain sensitivity are reported in individuals who routinely exercise yet, their association is unclear. Furthermore, it is unknown if the heightened vagal tone following high physical activity predicts and intensifies EIH. Fifty-one healthy participants (27 low-moderately physically active; 27 females) underwent a resting-state electrocardiogram followed by heart rate variability analysis. Pain measurements, including pressure (PPT) and heat (HPT) pain thresholds, ratings of tonic heat pain (THP) and conditioned pain modulation (CPM) paradigm, were conducted pre- and post-exercise on a cycle ergometer. The highly active group demonstrated higher vagal tone compared to the low-moderately active (root mean square of successive differences between R-R intervals: 63.96.92 vs. 34.78 ms, p = 0.018; percentage of successive R-R intervals that exceed 50 ms: 24.41 vs. 11.52%, p = 0.012). Based on repeated-measure ANOVA, the highly active group showed higher PPT at pre-exercise, compared to the low-moderately active group (382 kPa vs. 327 kPa; p = 0.007). Post-exercise, both groups demonstrated EIH, increased HPT (p = 0.013) and decreased THP ratings (p < 0.001). Linear regression revealed that only in the low-moderately active group, higher vagal tone was associated with more efficient pre-exercise CPM and a greater reduction in THP ratings post-exercise (p ≤ 0.01). Highly active individuals demonstrate greater vagal tone and lower pain sensitivity but no greater EIH. Vagal tone moderates pain inhibition efficiency and EIH only in low-moderately active individuals. These findings suggest that physical activity level moderates the vagal-pain association via the endogenous analgesia system. Highly physically active individuals exhibit greater vagal tone and reduced sensitivity to experimental pain, yet they do not benefit more from exercise-induced hypoalgesia (EIH) compared to low-moderately active individuals. Moreover, low-moderately active individuals with greater vagal tone exhibited more efficient endogenous pain inhibition and greater EIH, suggestive of the moderation effect of physical activity level on vagal-pain associations.

Exploring sleep heart rate variability: linear, nonlinear, and circadian rhythm perspectives.

Heart rate variability (HRV) is believed to possess the potential for disease detection. However, early identification of heart disease remains challenging, as HRV analysis in dogs primarily reflects the advanced stages of the disease. The aim of this study is to compare 24-h HRV with sleep HRV to assess the potential utility of sleep HRV analysis. Thirty healthy dogs with no echocardiographic abnormalities were included in the study, comprising 23 females and 7 males ranging in age from 2 months to 8 years (mean [standard deviation], 1.4 [1.6]). This study employed a cross-sectional study. 24-h HRV and sleep HRV were measured from 48-h Holter recordings. Both linear analysis, a traditional method of heart rate variability analysis, and nonlinear analysis, a novel approach, were conducted. Additionally, circadian rhythm parameters were assessed. In frequency analysis of linear analysis, the parasympathetic index nHF was significantly higher during sleep compared to the mean 24-h period (mean sleep HRV [standard deviation] vs. mean 24 h [standard deviation], 95% confidence interval, p value, r-family: 0.24 [0.057] vs. 0.23 [0.045], 0.006-0.031, p = 0.005, r = 0.49). Regarding time domain analysis, the parasympathetic indices SDNN and RMSSD were also significantly higher during sleep (SDNN: 179.7 [66.9] vs. 156.6 [53.2], 14.5-31.7, p < 0.001, r = 0.71 RMSSD: 187.0 [74.0] vs. 165.4 [62.2], 13.2-30.0, p < 0.001, r = 0.70). In a geometric method of nonlinear analysis, the parasympathetic indices SD1 and SD2 showed significantly higher values during sleep (SD1: 132.4 [52.4] vs. 117.1 [44.0], 9.3-21.1, p < 0.001, r = 0.70 SD2: 215.0 [80.5] vs. 185.9 [62.0], 17.6-40.6, p < 0.001, r = 0.69). Furthermore, the circadian rhythm items of the parasympathetic indices SDNN, RMSSD, SD1, and SD2 exhibited positive peaks during sleep. The findings suggest that focusing on HRV during sleep can provide a more accurate representation of parasympathetic activity, as it captures the peak circadian rhythm items.

Case-control study of heart rate variability and sleep apnea in childhood sickle cell disease.

Obstructive sleep apnea (OSA) is common in sickle cell disease (SCD) despite the absence of overweight, suggesting a specific pathophysiology. We previously showed that otherwise healthy children with increased pharyngeal compliance, a main endotype of OSA, exhibited decreased sympathetic modulation. Our objective was to assess whether modifications of heart rate variability (HRV) and compliance are associated in SCD. Cases (children with SCD, African or Caribbean ethnicity) and controls (otherwise healthy children, same ethnicity), aged 4-18 years, were selected from our database of children referred for OSA and matched for sex, age, and obstructive apnea-hypopnoea index (OAHI) score. The children underwent polysomnography and acoustic pharyngometry (to compute compliance). HRV analyses were performed from 5 min ECG recordings in wakeful, NREM, and REM sleep states and from the whole night. Twenty-one pairs were analysed (median age 10.5 years, 24 girls). Children with SCD had lower BMI z-scores and more tonsil hypertrophy than control children. Children with SCD and OSA (OAHI ≥2/hour) were characterised by lower compliance than children with SCD without OSA. An inverse relationship between compliance and SD2 (HRV from whole night, inversely related to sympathetic modulation) was evidenced (negative relationship in SCD: R = -0.63, p = 0.002 vs. positive relationship in controls R = 0.59, p = 0.006). In conclusion, while the decrease in sympathetic modulation in control children may contribute to increasing pharyngeal compliance, its decrease seems protective in children with sickle cell disease, which underlines the specificity of OSAS pathophysiology in SCD that could be due to sickle cell disease related smooth muscle dystonia.

Differences in the cardiovascular hemodynamic response between the Valsalva and Reverse Valsalva Maneuvers in healthy subjects.

The Valsalva Maneuver (VM) is the first-line treatment for paroxysmal supraventricular tachycardia, but a recent, novel, and efficient tool to restore sinus rhythm has been described, i.e., the Reverse Valsalva (RV). This study aims to compare changes in cardiovascular hemodynamics and autonomic system activity (ANS) based on heart rate variability (HRV) analysis during both maneuvers. Fifteen healthy participants performed the VM and RV maneuvers three times in a sitting position for durations of 15 s and 10 s, respectively. Blood pressure (BP) and heart rate (HR) were continuously monitored before, during and after the tests. Autonomic system activity was evaluated using frequency-domain analysis of HRV. The decrease in HR from baseline to the lowest values, expressed as a ratio, was similar during both maneuvers (0.81 during the RV vs. 0.79 during the VM, p = 0.27). However, the final lowest HR in response to the RV was higher than that in response to the VM, 70/min vs. 59/min (p <0.001). The activation of the autonomic nervous system during the most bradycardic phase of the RV (phase II) and VM (phase IV) showed that the total power of HRV was less prominent during the RV than during the VM (p <0.012), with similar levels of parasympathetic activation. Our results showed less HR slowdown during the RV than during the VM. The changes in HRV parameters during both procedures in particular phases of the RV and VM suggest that the autonomic nervous system is activated alternately, so these tests can be used complementarily in a clinical setting with different results.

Analysis of Heart Rate Variability in Individuals Affected by Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) produces alterations in the autonomic nervous system (ANS), which explains the cardiac manifestations observed in patients. The assessment of heart rate variability (HRV) is what best reflects the activity of the ANS on heart rate. The Polar H7 Bluetooth® device proves to be a non-invasive and much faster technology than existing alternatives for this purpose. The goal of this study is to determine HRV using Polar H7 Bluetooth technology in ALS patients, comparing the obtained measurements with values from healthy individuals. The sample consisted of 124 participants: 68 diagnosed with ALS and 56 healthy individuals. Using Polar H7 Bluetooth technology and the ELITE HRV application, various HRV measurements were determined for all participants, specifically the HRV index, RMSSD, RMSSD LN, SDNN index, PNN50, LF, HF, LF/HF ratio, HR average, and HF peak frequency. Statistically significant differences were observed between ALS patients and healthy individuals in the HRV index, RMSSD, RMSSD LN, SDNN index, PNN50, HF, and LF, where healthy individuals exhibited higher scores. For the HR average, the ALS group showed a higher value. Values were similar when comparing men and women with ALS, with only a higher HF peak frequency observed in women. The Polar H7 Bluetooth® device is effective in determining heart rate variability alterations in ALS, being a promising prognostic tool for the disease.

Enhancing emotion regulation: investigating the efficacy of transcutaneous electrical acupoint stimulation at PC6 in reducing fear of heights.

This study investigated the impact of transcutaneous electrical acupoint stimulation (TEAS) at Neiguan acupoint (PC6) on the physiological and behavioral responses of participants exposed in virtual height. 40 participants were included in the study and were randomly assigned to either a control group or an intervention group. Participants had an immersive experience with a VR interactive platform that provided somatosensory interaction in height stimulation scenes. Psychological scores, behavioral and cognitive performance, and physiological responses were recorded and analyzed. The results indicated that the intervention group had significantly lower fear scores compared to the control group. Analysis of heart rate variability revealed that the intervention group exhibited improved heart rate variability, indicating enhanced cardiovascular function and emotion regulation. The behavioral and cognitive results demonstrated that the intervention group exhibited higher left eye openness, faster reaction times, and greater movement distance, suggesting enhanced attentional focus, cognitive processing, and reduced avoidance behaviors. These findings suggest that TEAS at PC6 can effectively reduce fear and improve the regulation of physiological and behavioral responses to negative emotional stimuli.

Cardiac Rhythm Aberrations in Subacute Sclerosing Panencephalitis: Insights From Heart Rate Variability Analysis.

Subacute sclerosing panencephalitis (SSPE) is a fatal neurological disorder resulting from persistent measles virus infection within the brain. Although neurological manifestations have been well-documented, the impact of SSPE on cardiac autonomic function, assessed through heart rate variability (HRV), remains understudied. In this prospective single-center study conducted from January 2022 to March 2023 in Southern India, 30 consecutive SSPE patients and age- and sex-matched controls underwent electrocardiogram recordings for HRV analysis. Various HRV parameters were assessed, including time-domain metrics (SD of normal-to-normal intervals, root mean square of successive differences between normal heartbeats, percentage of successive normal interbeat intervals greater than 50 msec), SD1 and SD2 for Poincaré plot analysis, and frequency-domain metrics (low frequency %, high frequency %, low frequency:high frequency ratio). In the study, SSPE patients exhibited markedly reduced HRV. Specifically, SD of normal-to-normal intervals (P = 0.003), percentage of successive normal interbeat intervals greater than 50 msec (P = 0.03), and SD2 (P = 0.0016) were significantly lower compared with controls. Frequency-domain analysis did not reveal significant distinctions. Correlation analysis demonstrated a negative relationship between percentage of successive normal interbeat intervals greater than 50 msec and SSPE severity (r = -0.37, P = 0.042). Heart rate variability did not significantly differ between SSPE stages or with clinical variables. The interbeat interval range showed a narrower distribution in SSPE subjects. Our study highlights the clinical relevance of HRV analysis in SSPE and autonomic dysfunction throughout the disease course underscoring its importance in SSPE. This investigation provides valuable insights into cardiac autonomic dysfunction probably because of affliction of the central autonomic networks caused by the disease process and may be a contributing factor to mortality in SSPE.

Heart rate variability: Obtaining the stress score from SDNN values

BACKGROUND: Heart Rate Variability (HRV) is a non-invasive method of assessing the autonomic nervous system response during exercise and fatigue. OBJECTIVE: The aim of the study was to analyze the validity and feasibility of the stress score index (SS) calculated from SDNN values during exercise. METHODS: 18 Men performed 2 running tests: 1) incremental exercise test; 2) 10-minute constant load test. Subjects underwent HRV analysis during the constant load test, before both tests, and afterward in a seated position at 3 intervals (0’–5’, 5’–10’, 10’–15’). The relationship between SDNN and SD2 was analyzed before, during, and after the test. SS was calculated as 1/SD2*1000. The Bland-Altman test analyzed the reliability of ESS. The bias, limits of agreement (LoA), standard deviation of difference, intraclass correlation (ICC), and person coefficient were calculated. RESULTS: The bias was 0.15 ± 2.54 (UperLOA: 2.54; LowerLOA: -2.23). In all conditions, SD2 and SDNN showed a positive linear relationship (r2 = 0.986); SS and ESS were correlated; and SS and ESS described a positive linear relationship (r2 = 0.993). CONCLUSIONS: The SS index calculation from SDNN is a reliable alternative during exercise.

Continuous Long-Term Assessment of Heart Rate Variability in Adults with Cyanotic Congenital Heart Disease after Surgical Repair.

Background: Heart rate variability (HRV) is an established, non-invasive parameter for the assessment of cardiac autonomic nervous activity and the health status in general cardiology. However, there are few studies on HRV in adults with congenital heart defects (CHDs). The aim of the present study was to evaluate the use of long-term continuous HRV measurement for the assessment of global health status in adults with cyanotic CHD. Methods: This prospective study included 45 adults (40% female, mean age = 35.2 ± 9.2 [range: 19-58] years) after cardiac surgical repair. HRV parameters were calculated from continuous 24 h measurements using a Bittium Faros 180 sensor (Bittium Corp., Oulu, Finland). Results: Postoperative patients with transposition of the great arteries (TGA) (n = 18) achieved significantly higher values of standard deviation of NN intervals (SDNN) (175.4 ± 59.9 ms vs. 133.5 ± 40.6 ms; p = 0.013) compared with patients with other conotruncal anomalies (n = 22). Comparing patients with TGA after a Senning-Brom or Mustard operation (n = 13) with all other heart surgery patients (n = 32), significantly higher HRV parameters were found after atrial switch (root mean square of successive RR interval differences: 53.6 ± 20.7 ms vs. 38.4 ± 18.3 ms; p = 0.019; SDNN: 183.5 ± 58.4 ms vs. 136.3 ± 45.3 ms; p = 0.006). A higher SDNN was also measured after Senning-Brom or Mustard operations than after a Rastelli operations (n = 2) (SDNN: 183.5 ± 58.4 ms vs. 84.5 ± 5.2 ms; p = 0.037). When comparing atrial switch operations (n = 3) with Rastelli operations, the SDNN value was significantly shorter in the Rastelli group (p = 0.004). Conclusions: Our results suggest that continuous HRV monitoring may serve as a marker of cardiac autonomic dysfunction in adults with cyanotic CHD after surgical repair. Impaired cardiac autonomic nervous activity may be associated with an increased risk of adverse reactions in patients with repaired CHD. Therefore, a longitudinal assessment of HRV patterns and trends may provide a deeper insight into dynamic changes in their autonomic regulation and disease progression, lifestyle changes, or treatments. As each person has individual variability in heart rate, HRV may be useful in assessing intra-individual disease progression and may help to improve personalized medicine. Further studies are needed to better understand the underlying mechanisms and to explore the full potential of HRV analysis to optimize medical care for ACHDs.

Use of a wearable device to compare subjective and objective fatigue in lung cancer patients and cancer-free controls

PurposeThe study evaluates the use of heart rate variability (HRV), a measure of autonomic nervous system (ANS) modulation via wearable smart bands, to objectively assess cancer-related fatigue (CRF) levels. It aims to enhance understanding of fatigue by distinguishing between LF/HF ratios and LF/HF disorder ratios through HRV and photoplethysmography (PPG), identifying them as potential biomarkers. MethodsSeventy-one lung cancer patients and 75 non-cancer controls wore smart bands for one week. Fatigue was assessed using Brief Fatigue Inventory, alongside sleep quality and daily interference. HRV parameters were analyzed to compare groups. ResultsCancer patients showed higher fatigue and interference levels than controls (64.8% vs. 54.7%). Those with mild fatigue had elevated LF/HF disorder ratios during sleep (40% vs. 20%, P = 0.01), similar to those with moderate to severe fatigue (50% vs. 20%, P = 0.01), indicating more significant autonomic dysregulation. Notably, mild fatigue patients had higher mean LF/HF ratios than controls (1.9 ± 1.34 vs. 1.2 ± 0.6, P = 0.01), underscoring the potential of disorder ratios in signaling fatigue severity. ConclusionsUtilizing wearable smart bands for HRV-based analysis is feasible for objectively assess CRF levels in cancer patients, especially during sleep. By distinguishing between LF/HF ratios and LF/HF disorder ratios, our findings suggest that wearable technology and detailed HRV analysis offer promising avenues for real-time fatigue monitoring. This approach has the potential to significantly improve cancer care by providing new methods for managing and intervening in CRF, particularly with a focus on autonomic dysregulation as a crucial factor.

Predominant cardiac sympathetic modulation during wake and sleep in patients with Rett syndrome

BackgroundRett syndrome (RTT) is a rare neurological disorder primarily associated with mutations in the methyl-CpG-binding protein 2 (MECP2) gene. The syndrome is characterized by cognitive, social, and physical impairments, as well as sleep disorders and epilepsy. Notably, dysfunction of the autonomic nervous system is a key feature of the syndrome. Although Heart Rate Variability (HRV) has been used to investigate autonomic nervous system dysfunction in RTT during wakefulness, there is still a significant lack of information regarding the same during sleep. Therefore, our aim was to investigate cardiovascular autonomic modulation during sleep in subjects with RTT compared to an age-matched healthy control group (HC). MethodA complete overnight polysomnographic (PSG) recording was obtained from 11 patients with Rett syndrome (all females, 10 ± 4 years old) and 11 HC (all females, 11 ± 4 years old; p = 0.48). Electrocardiogram and breathing data were extracted from PSG and divided into wake, non-REM, and REM sleep stages. Cardiac autonomic control was assessed using symbolic non-linear heart rate variability analysis. The symbolic analysis identified three patterns: 0 V% (sympathetic), 2UV%, and 2LV% (vagal). ResultsThe 0 V% was higher in the RTT group than in the HC group during wake, non-REM, and REM stages (p < 0.01), while the 2LV and 2UV% were lower during wake and sleep stages (p < 0.01). However, the 0 V% increased similarly from the wake to the REM stage in both RTT and HC groups. ConclusionsTherefore, the sympatho-vagal balance shifted towards sympathetic predominance and vagal withdrawal during wake and sleep in RTT, although cardiac autonomic dynamics were preserved during sleep.

Recovery of cardiac electrophysiological alterations by heart rate complexity based on multiscale entropy following liver transplantation

Autonomic nervous dysfunction is a known cardiac sequalae in patients with end-stage liver disease and is associated with a poor prognosis. Heart rate analysis using nonlinear models such as multiscale entropy (MSE) or complexity may identify marked changes in these patients where conventional heart rate variability (HRV) measurements do not. To investigate the application of heart rate complexity (HRC) based on MSE in liver transplantation settings. Thirty adult recipients of elective living donor liver transplantation were enrolled. HRV parameters using conventional HRV analysis and HRC analysis were obtained at the following time points: (1) 1 day before surgery, (2) postoperative day (POD) 7, (3) POD 14, (4) POD 90, and (5) POD 180. Preoperatively, patients with MELD score ≥ 25 had significantly lower HRC compared to patients with lower MELD scores. This difference in HRC disappeared by POD 7 following liver transplantation and subsequent analyses at POD 90 and 180 continued to show no significant difference. Our results indicated a significant negative correlation between HRC based on MSE analysis and liver disease severity preoperatively, which may be more sensitive than conventional linear HRV analysis. HRC in patients with MELD score ≧ 25 improved over time and became comparable to those with MELD < 25 as early as in 7 days.

Heart Rate Variability Analysis in Obstructive Sleep Apnoea Patients with Daytime Sleepiness.

Recent studies suggest sleepy patients with OSA are at higher risk for incident cardiovascular disease. This study assessed cardiac autonomic function in sleepy versus non-sleepy patients with obstructive sleep apnoea (OSA) using heart rate variability (HRV) analysis. We hypothesised that HRV profiles of sleepy patients would indicate higher cardiovascular risk. Electrocardiograms (ECG) derived from polysomnograms (PSG) collected by the Sydney Sleep Biobank were used to study HRV in groups of sleepy (ESS≥10) and non-sleepy OSA patients (ESS<10). HRV parameters were averaged across available ECG signal during N2 sleep. A total of 421 patients were evaluated, with mean age of 54 (14) years, body mass index (BMI) of 33 (9) kg/m2, apnoea hypopnoea index (AHI) of 21 (28) events/h and, 66% male. The sleepy group consisted of 119 patients, and the non-sleepy group 302 patients. Sleepy patients exhibited lower HRV values for: root mean square successive difference (RMSSD, p= 0.028); total power (TP, p= 0.031); absolute low frequency (LF, p= 0.045); and high frequency (HF, p= 0.010) power compared to Non-Sleepy patients. Sleepy patients with moderate to severe OSA exhibited lower HRV values for: (RMSSD, p= 0.045; TP, p= 0.052) ; absolute LF (p= 0.051); and HF power (p= 0.025). There were no differences in other time and frequency domain HRV markers. This study shows a trend towards parasympathetic withdrawal in sleepy OSA patients, particularly in moderate to severe cases, lending mechanistic support to the link between the sleepy phenotype and CVD risk in OSA.

Features of neurovegetative and humoral regulation of cognitive activity in adolescents when using electronic devices

Background. Studying the functional state of the body of adolescents when they preform cognitive activity using electronic devices is of great importance due to the introduction of information and computer technologies into the educational process. Identifying the characteristics of the reactivity of students’ bodies when performing cognitive activities in  a  digital environment will contribute to  both optimization of learning and health protection.The aim. To study the autonomic regulation of heart rate, electrodermal activity, cerebral circulation and the level of cortisol in saliva when adolescents performed a cognitive test on electronic devices (tablet, laptop) and on paper.Materials and  methods. Using analysis of heart rate variability, electrodermal activity, rheoencephalography and enzyme-linked immunosorbent determination of cortisol in saliva, цe examined 48 adolescents while performing a cognitive activity on electronic devices.Results. When adolescents perform cognitive activity using electronic devices, we can register changes in heart rate variability, electrodermal activity and cerebral circulation. Cognitive activity in a digital environment causes an increase in sympathetic effect ontheheart rate with adecrease inparasympathetic activity, anincrease inthe integrative indicator ofgalvanic skin response, invascular tone and adecrease in the cerebral blood flow intensity. One in four adolescents experiences anticipatory stimulation of the endocrine system before taking a cognitive test. Correlation analysis revealed alarge number of correlations between the studied indicators both in the initial state and during cognitive activity.Conclusion. A large number of correlations, both in the initial state and during the cognitive test, between heart rate variability and cortisol concentration, cerebral circulation parameters indicate the preservation of a rigid system of neurovegetative and humoral regulation of heart rate when using electronic devices compared to paper-based media.