A Study of Significant data Classification between EDR extracted and frequency analysis of Heart Rate Variability from ECG using Conductive textile

Background: Total spinal anesthesia (TSA) after injections of local anesthetics into the intrathecal space during epidural anesthesia is not rare. TSA anesthetizes cranial nerves and peripheral nerves, causes specific circulatory disturbances related to autonomic imbalance. Spectral analysis of heart rate variability (HRV) and blood pressure variability (BPV) provide a dynamic assessment of sympathetic and parasympathetic tone. Cross-spectral analysis has been used to emphasize this dynamic baroreflex control of HR as a frequency-dependent phenomenon and allows an assessment of baroreflex function. To examine the effects of TSA on the autonomic nervous system, we used spectral and cross-spectral analytic methods. Methods: We investigated 14 rats before and after TSA. Power spectral densities of blood pressure (BP) and heart rate (HR) were estimated by fast Fourier transform. To evaluate the effect of TSA on baroreflex function, the cross spectral gain, phase, and coherence between beat-to-beat BP and HR signals were calculated by using transfer function analysis. Results: With the onset of TSA, BP and HR significantly decreased. TSA significantly decreased the low frequency (LF) and high frequency (HF) components of HRV and BPV. Baroreflex sensitivity (BRS) obtained from transfer function gain between these variables was significantly decreased. Conclusions: TSA reduces the LF and HF components of HRV and BPV. These suggest that TSA in rats decreases both parasympathetic and sympathetic drive. Moreover, the decrease in BRS suggests impairment of cardiac baroreflex buffering function during TSA.

Characteristics of high frequency (HF) component based on heart rate variability (HRV) in a large general population remain unclear, particularly on the relationship with daily physical activity. We aimed to characterize the distribution of HF component and examine the association with daily physical activity among community residents. We performed spectral analysis of HRV from 10-second ECG recordings among 9135 residents aged 30 to 74 years in Nagahama City, Japan. HF components were log-transformed to consider the distribution. Simple correlations between HF and age were determined. Age-adjusted mean values of HF component were calculated for each questionnaire item related to daily physical activity. Multiple regression analysis was performed to examine the effect of daily physical activity on HF component value. Mean values of logarithmically-transformed HF component (lnHF) were higher in women than in men (p < 0.001). lnHF was inversely associated with age (r = -0.40, -0.49 for men, women, respectively). Adjusted mean lnHF for physically active people was significantly higher than that in inactive people (p < 0.001). HF components from 10-second ECG recordings were moderately and negatively correlated with age in both sexes, and positively correlated with daily physical activity in the general adult population. Maintaining the level of daily physical activity, especially to exercise regularly could keep the parasympathetic function high.

The Mars500 project was conceived to gather knowledge about the psychological and physiological effects of living in an enclosed environment during 520 d as would be required for a real mission to Mars. Our objective was to investigate the circadian profile of heart rate variability (HRV) in the context of the Mars500 study. Before, during, and after confinement, 24-h EKG records were obtained from the six crewmembers who participated in the mission. Autonomic activity was evaluated through time and frequency domain indexes of HRV analysis. Circadian rhythmicity was assessed both by averaging hourly HRV along wake and sleep scheduled periods and by fitting a 24-h harmonic to the hourly means. During confinement, wake HRV showed (mean +/- SE) a progressive increase in mean RR interval (from 778 +/- 24 ms to 916 +/- 42 ms), and in the amplitude (values are wavelet power coefficients) of very low (from 13.3 +/- 0.3 to 14.1 +/- 0.2) and high (from 7.8 +/- 0.4 to 8.3 +/- 0.3) frequency components. During sleep, the relative amplitude of the high frequency component of HRV decreased (from 11.8 +/- 1.6 to 9.4 +/- 1.8 normalized units). Overall, sleep-wake differences of HRV showed a progressive decrease of the relative amplitude of the high frequency component. Also, circadian HRV rhythms were dampened during confinement. Data revealed diminished amplitude of the rest-activity pattern of the autonomic nervous system parasympathetic function. Reduced daylight exposure and mood changes could account for this observation.

We read with great interest the arguments presented by Coote & White (2015) in favour of the traditional view that exercise training decreases resting heart rate by an increase in the tonic discharge of the vagal nerves. However, we are not persuaded. Coote & White (2015) quote Maciel et al. (1985); however, Maciel et al. (1985) showed that the intrinsic heart rate of trained athletes remains lower after full vagal nerve block. Although Ordway et al. (1982) reported that there was no training-induced bradycardia in six cardiac-denervated dogs, there is evidence to the contrary: Kavanagh et al. (1988) reported that in eight highly compliant cardiac transplant patients (with no evidence of cardiac reinnervation) there was. Coote & White (2015) state that the high frequency (HF) component of heart rate variability (HRV) is a robust surrogate for vagal tone and the increase in the HF component in athletes is evidence of increased vagal tone. However, we have argued that HRV cannot be used in any simple way to measure autonomic nerve activity (Monfredi et al. 2014). Our arguments are based on those of Zaza & Lombardi (2001), who showed that the HF component (like other measures of HRV) is highly sensitive to the heart rate. For example, on training Al-Ani et al. (1996) observed a 12 beats min–1 decrease in the resting heart rate (69 decreased to 57 beats min–1) and a 1.5-fold increase in the HF component, whereas Zaza & Lombardi (2001) calculated that a 10 beats min–1 decrease (70 to 60 beats min–1) will cause a 3-fold increase simply because of the decrease in heart rate alone. Coote & White (2015) mention the sensitivity of the baroreceptor–heart rate reflex; this is a commonly used index of autonomic balance, but this too relies on HRV and is therefore flawed (Zaza & Lombardi (2001). The data from Danson & Paterson (2003) quoted by Coote & White (2015) showing a training-induced upregulation of NOS-1 in intracardiac cholinergic ganglia are fascinating; the data indicate an improvement in vagal neurotransmission but this does not prove it is responsible for the training-induced bradycardia. For example, our own data demonstrate a training-induced reduction in the sinus node of mRNA for the M2 receptor and Kir3.1, Kir3.4, HCN4, Cav1.2 and Cav1.3 channels (responsible for the ACh-sensitive currents IK,ACh, If and ICa,L) (D'Souza et al. 2014); these changes potentially reduce the sensitivity of the sinus node to vagal tone. Overall, given that direct recording of cardiac vagal activity is currently unfeasible, the available evidence tips the balance in favour of electrophysiological remodelling of the sinus node to explain the resting bradycardia in athletes. A challenge for neuroscientists is to measure vagal activity to the sinus node directly and not rely on questionable surrogates. Readers are invited to give their views on this and the accompanying CrossTalk articles in this issue by submitting a brief (250 word) comment. Comments may be submitted up to 6 weeks after publication of the article, at which point the discussion will close and the CrossTalk authors will be invited to submit a ‘Last Word’. Please email your comment to jphysiol@physoc.org. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. None declared.

Music is known to reduce pain, anxiety and fear in several stressful conditions in both males and females. Further, listening to preferred music enhances the endurance during running performance of women rather than listening to non-preferred music. In recent years Heart Rate Variability (HRV) has been used as an indicator of autonomic nervous activity. This study was aimed to assess the effectiveness of preferential music on HRV after moderate exercise. This was an experimental study done in 30 healthy students aged between 20-25 years, of either sex. HRV was measured at rest, 15 minutes of exercise only and 15 minutes of exercise with listening preferential music in same participants. Data was analysed by One-Way ANOVA and Tukey HSD Post-hoc Test. Statistical significance was taken to be a p-value of less than 0.05. Low frequency and high frequency component was significantly increased followed by only exercise. Music minimized increase in both high and low frequency component followed by exercise. However, only high frequency change was statistically significant. LF/HF ratio was significantly increased followed by only exercise. Music significantly minimized increase in LF/HF ratio. This study provides the preliminary evidence that listening to preferential music could be an effective method of relaxation, as indicated by a shift of the autonomic balance towards the parasympathetic activity among medical students.

Altered vascular responses during exercise and disturbed responses to autonomic function testing have been documented in hypertrophic cardiomyopathy (HCM) and are associated with markers of an adverse prognosis. Reduced heart rate variability (HRV) and baroreflex sensitivity are predictors of increased risk of sudden death after myocardial infarction, but the value of these parameters in HCM is unknown. To determine the clinical significance of HRV and its relation to markers of electrical and hemodynamic instability in HCM, the 24-hour Holter recordings of 104 patients in sinus rhythm and off medication were analyzed. Five nonspectral measures of HRV were computed. The frequency components of HRV were calculated by fast Fourier transformation of the RR time intervals; the areas under the low (0.04 to 0.15 Hz) and high (0.15 to 0.4 Hz) frequency portions of the spectrum were measured as indices of autonomic and specific vagal influences on HRV, respectively. Spectral and nonspectral measures were compared with clinical, echo/Doppler, and Holter variables. ANCOVA was performed to allow for the effect of age on differences between variables. Spectral and nonspectral measures of HRV were correlated (r > .65; P < or = .001), indicating that the different time-domain and frequency parameters reflected similar measures of HRV. Global measures of HRV including the standard deviation of the mean of RR intervals (SDRR) and the standard deviation of 5-minute mean RR intervals (SDANN) were increased in patients with an adverse family history of HCM (173 +/- 67 vs 131 +/- 38 milliseconds, P = .001, and 158 +/- 66 vs 116 +/- 36 milliseconds, P = .004, respectively). In patients with exertional chest pain, global nonspectral measures were reduced compared with asymptomatic patients (118 +/- 31 vs 152 +/- 53 milliseconds, P = .006, and 105 +/- 30 vs 136 +/- 52 milliseconds, P = .014, respectively). Specific vagal influences on HRV including the proportion of RR intervals more than 50 milliseconds different (PNN50) and the high frequency peak on spectral analysis were less in patients with supraventricular arrhythmias on Holter monitoring (7.2 +/- 8 vs 16 +/- 13%, P = .012, and 21 +/- 10 vs 28 +/- 13 milliseconds, P = .048, respectively). Similarly, both global and specific vagal measures of HRV were less in the 27 patients with nonsustained ventricular tachycardia on Holter (PNN50, 7.7 +/- 9 vs 15 +/- 13 milliseconds, P = .048, and high frequency component, 19 +/- 9 vs 28 +/- 13 milliseconds, P = .05. During follow-up, 10 patients, 9 of whom were aged less than 33 years, experienced catastrophic events; 6 were resuscitated from ventricular fibrillation and 4 died suddenly. Indices of HRV were similar in these 10 patients to indices in the 94 survivors. Time-domain and spectral measures of HRV yield similar information about the specific autonomic influences on the heart. Global and specific vagal influences on HRV were reduced in patients with symptoms and arrhythmias and global HRV is increased in patients with an adverse family history of HCM, but these indices do not add to the predictive accuracy of established risk factors.

Association of estrogen receptor-α gene polymorphisms with cardiac autonomic nervous activity in healthy young Japanese males

Background: Sudden cardiac death (SCD) after myocardial infarction, most commonly caused by ventricular fibrillation, is closely associated with autonomic nervous tone. However, the mechanism of SCD and its association with autonomic nervous tone and the circadian rhythm of this tone remain obscure. We examined the characteristics of autonomic nervous tone in patients with SCD using heart rate variability (HRV) analysis.Methods: HRV was analyzed by spectral and nonspectral methods in 46 postinfarction patients, including 6 patients who experienced SCD (SCD[+]) and 40 survivors (SCD[—]). The circadian rhythm of HRV was assessed by a nonlinear least squares method combined with the maximum entropy method (MEM) using data from 24‐hour ambulatory ECGs. The mean follow‐up period was 27 ± 12 months.Results: Midline estimating statistic of rhythm and the amplitude of the high frequency (HF) component in the SCD(+) group were lower than those in the SCD(—) group, and differences of the circadian rhythm of the HF component between the SCD(+) group and the SCD(—) group were observed.Conclusions: A decreased HF component indicating diminished parasympathetic nervous activity was the strongest independent predictor of SCD. These results suggest that postinfarction patients whose parasympathetic nervous activity is low and whose circadian changes are small may be susceptible to SCD.

Intradialytic hypotension, a major source of morbidity during hemodialysis and ultrafiltration, is often accompanied by paradoxical bradycardia. Relatively little is known about the sequential changes in autonomic nervous system activity up to and during the hypotensive episode. Continuous, beat-to-beat measurements of BP and heart rate were made during hemodialysis in patients prone (n = 8) and not prone (n = 11) to develop intradialytic hypotension. Off-line spectral analysis of heart rate variability (HRV) was performed to assess changes in autonomic nervous system activity during dialysis sessions both with and without hypotension. The low frequency (LF) component of HRV is thought to correlate with sympathetic nervous system activity, the high frequency (HF) component with that of the parasympathetic nervous system. In the sessions not complicated by symptomatic hypotension (n = 26), mean arterial BP (MAP) hardly fell, whereas heart rate increased from 77 +/- 2 to 89 +/- 5 bpm (P < 0.05). The LF component of HRV increased from 45.2 +/- 5.0 normalized units (nu) to 59.9 +/- 4.9 nu (P < 0.05), whereas the HF component fell from 54.8 +/- 5.0 to 40.2 +/- 4.4 nu (P < 0.05). These changes agree with compensatory baroreflex-mediated activation of the sympathetic nervous system (and suppressed parasympathetic activity) during ultrafiltration-induced intravascular volume depletion. In the sessions complicated by severe symptomatic hypotension (n = 22), the changes in heart rate and the results of spectral analysis of HRV were similar to those reported above up to the moment of sudden symptomatic (nausea, vomiting, dizziness, cramps) hypotension, whereas MAP had already fallen gradually from 94 +/- 3 to 85 +/- 3 mmHg (P < 0.05). The sudden further reduction in MAP (to 55 +/- 2 mmHg, P < 0.02) was invariably accompanied by bradycardia (heart rate directly before hypotension 90 +/- 2 bpm, during hypotension 69 +/- 3 bpm, P < 0.002). The LF component of HRV fell from 62.8 +/- 4.6 nu directly before to 40.0 +/- 3.7 nu (P < 0.05) during hypotension, whereas the HF component increased from 37.9 +/- 4.7 to 60.3 +/- 3.7 nu (P < 0.05). These findings agree with activation of the cardiodepressor reflex, involving decreased sympathetic and increased parasympathetic nervous system activity, respectively. These findings indicate that activation of the sympatho-inhibitory cardiodepressor reflex (Bezold-Jarisch reflex), which is a physiologic response to a critical reduction in intravascular volume and cardiac filling, is the cause of sudden intradialytic hypotension.

HighlightsWhat are the main findings?A 6-week randomized controlled trial examined guided breathing with and without nocturnal mouth taping in women with dysfunctional breathing.Both groups showed significant reductions in respiratory rate and perceived stress after the breathing program.Only the mouth-taping group demonstrated significant improvements in the high-frequency component of HRV and Hencho breath-hold performance.The multi-component breathing intervention was safe, low-cost, and feasible in a community fitness setting.What is the implication of the main finding?Findings support physiotherapy-led breathing interventions as a non-pharmacological strategy to enhance autonomic regulation and respiratory efficiency.Background: Dysfunctional breathing patterns may impair autonomic regulation and increase perceived stress. Breathing-based interventions, particularly those involving guided exercises and supportive tools, have the potential to provide non-pharmacological benefits. Methods: In this parallel two-arm randomized controlled trial, 14 women aged 35–45 years with signs of dysfunctional breathing and no comorbidities were recruited from a fitness club. Participants were randomly assigned (1:1) using a computer-generated sequence to an intervention group (n = 7) or a control group (n = 7). Blinding was not applied. Both groups completed a 6-week program of guided breathing exercises using the iBreathe app, while the intervention group additionally used mouth tape during sleep. The primary outcomes were heart rate variability (HRV) indices—root mean square of successive differences (RMSSD) and the high-frequency (HF) component. Secondary outcomes included respiratory rate, Hencho test performance, and perceived stress measured using the Perceived Stress Scale-10 (PSS-10) and a Visual Analogue Scale (VAS). All participants were included in the final analysis (no loss to follow-up). Results: The intervention group showed a significant increase in the HF component of HRV (p = 0.018) and improved Hencho test performance (p = 0.018). Both groups demonstrated significant reductions in respiratory rate (p < 0.05) and PSS scores (p < 0.05). Between-group differences were not significant for RMSSD or perceived stress. No adverse events were reported. Conclusions: A 6-week breathing intervention improved respiratory efficiency and reduced perceived stress among women with dysfunctional breathing. The additional of night-time mouth taping provided further benefits for HRV and respiratory control. Larger and longer trials are needed to confirm these findings.

The necessity of respiratory monitoring is rapidly increasing in medical field to diagnose various cardio-pulmonary diseases. It is difficult to monitor respiration for ambulatory and ICU patients, as conventional methods are either obtrusive or suffer from low accuracy. The extraction of ECG derived respiration (EDR) signal using single-lead ECG has been proposed lately. This allows monitoring of ECG and respiration signal simultaneously from a recorded ECG signal. Recently few methods for EDR extraction from ECG are reported in literature. In this work, respiratory rates (RR) are derived from Heart Rate Variability (HRV) and Peak Amplitude Variation (PAV) method and a comparative study of these two methods is reported. Moreover, the validation of the proposed methods is made by comparing the obtained RR with that derived from original respiration signal. Subjects from Fantasia database and real-time data for both normal and with pulmonary diseases are considered for the work.

The analysis and interpretation of heart rate variability (HRV) during exercise is challenging not only because of the nonstationary nature of exercise, the time-varying mean heart rate, and the fact that respiratory frequency exceeds 0.4 Hz, but there are also other factors, such as the component centered at the pedaling frequency observed in maximal cycling tests, which may confuse the interpretation of HRV analysis. The objectives of this study are to test the hypothesis that a component centered at the running stride frequency (SF) appears in the HRV of subjects during maximal treadmill exercise testing, and to study its influence in the interpretation of the low-frequency (LF) and high-frequency (HF) components of HRV during exercise. The HRV of 23 subjects during maximal treadmill exercise testing is analyzed. The instantaneous power of different HRV components is computed from the smoothed pseudo-Wigner-Ville distribution of the modulating signal assumed to carry information from the autonomic nervous system, which is estimated based on the time-varying integral pulse frequency modulation model. Besides the LF and HF components, the appearance is revealed of a component centered at the running SF as well as its aliases. The power associated with the SF component and its aliases represents 22±7% (median±median absolute deviation) of the total HRV power in all the subjects. Normalized LF power decreases as the exercise intensity increases, while normalized HF power increases. The power associated with the SF does not change significantly with exercise intensity. Consideration of the running SF component and its aliases is very important in HRV analysis since stride frequency aliases may overlap with LF and HF components.

S22 INTRODUCTION: Anesthesia induction with the combination of midazolam (M) and barbiturate (B) reduces hemodynamic changes during intubation as compared to induction with B alone [1]. In this study, we investigated the changes in autonomic nervous system activity during anesthesia induction with the combination of M and B using the analysis of heart rate (HR) variability and plasma catecholamine concentrations. METHODS: After institutional approval and informed consent, 40 patients (30-70 years) were randomly divided into the combination (M+B) group and the B group (each 20 patients). Atropine (0.01mg/kg) and hydroxyzine (1mg/kg) were administered intramuscularly 30 minutes before anesthesia induction. Anesthesia was induced with 0.1mg/kg M with 3mg/kg thiopental [2] or with 5mg/kg thiopental. Tracheal intubation was facilitated with 0.15mg/kg vecuronium. Anesthesia was maintained with 31/min nitrous oxide and 21/min oxygen. Arterial blood pressure (radial artery), HR, plasma concentrations of epinephrine (E) and norepinephrine (NE) (high-performance liquid chromatography), and HR variability (spectral analysis by LRR-03[trade mark sign] and MemCalc[trade mark sign], GMS, Tokyo, Japan) were measured before induction up to 5 minutes after intubation. The high frequency component (HF, 0.15-0.4 Hz) of HR variability is thought to indicate parasympathetic activity and the ratio of low frequency component (LF, 0.04-0.15 Hz) to HF is thought to indicate sympathetic activity [3,4]. Two way repeated measures analysis of variance followed by the contrasts was used for statistical analysis (P<0.05). RESULTS: Blood pressure, HR, and plasma concentrations of E and NE increased during intubation with significantly higher values in the B group. HF and the LF/HF ratio were significantly higher in the B group than in the M+B group during intubation (Figure 1, Figure 2). After intubation, LF/HF ratio was still higher while HF was lower in the B group as compared to the M+B group mean +/- SEM,: B group,: M+B group, A: before induction, B: before intubation, C: during intubation, D: 1 minute after intubation, E: 5 minutes after intubation, *: P<0.05, **: P<0.01 vs. B group.Figure 1Figure 2DISCUSSION: The higher blood pressure, HR, plasma concentrations of E and NE, and LF/HF ratio in HR variability during intubation in the B group indicate a higher sympathetic activity. Cardiac parasympathetic activity, which was shown by the HF, was also activated in the B group. Both sympathetic and parasympathetic activities were stable in the M+B group. It is concluded that the anesthesia induction with combination of midazolam and barbiturate can provide stable sympathetic and parasympathetic activities during intubation.

ECG-derived respiration: A promising tool for sleep-disordered breathing diagnosis in chronic heart failure patients

Acute mountain sickness (AMS) is a common condition among non-acclimatized individuals ascending to high altitude. Exercise, a characteristic feature of hiking and mountaineering, has been suggested to exacerbate AMS prevalence and to cause modifications of the autonomic nervous system. A reduction of the heart rate variability (HRV) is a common finding during acute hypoxia, however characteristics of HRV during exercise in subjects suffering from AMS are unknown. Therefore, the aim of the present study was to investigate the effects of acute normobaric hypoxia (FiO2=11.0% ≙ 5 500 m) at rest (PHE) and during exercise (AHE) on the cardiac autonomic function and the development of AMS in 20 healthy, male individuals. HRV recordings were performed during normoxia and after 2, 4, 6 and 8 h in hypoxia during PHE and AHE, respectively. AMS was assessed using the Lake Louise Score. During PHE 50% of participants developed AMS and 70% during AHE (p=0.22). The analysis of HRV data showed a significant reduction of total power (TP), high frequency (HF) and low frequency (LF) components and an increase of the LF:HF ratio during PHE, however without further modification during AHE. Exercise did not increase AMS prevalence or severity, but increased "non-gastrointestinal" symptoms including headache, fatigue and dizziness. HRV indices were not related to the overall incidence of AMS or the development of "non-gastrointestinal" symptoms but we detected significant correlations between gastrointestinal complaints and HRV components. Thus, we suggest that the cardiac autonomic modulation during acute normobaric hypoxia does not play an important role in the development of AMS, but seems to be related to gastrointestinal complaints at high altitude. However, the influence of moderate exercise on HRV and AMS is minor, only "non-GI" symptoms seem to be exacerbated when exercise is applied.