RMSSD Values Research Articles

Comparison of Workplace Posture on Heart Rate Variability between Exercising and Non-Exercising Traffic Police

Background: This study aimed to investigate heart rate variability among traffic police officers and compare these parameters between exercising and non-exercising groups. Heart rate variability is an important marker of cardiac autonomic function. Understanding the impact of exercise on heart rate variability among traffic police officers can provide valuable insights into strategies for improving their cardiovascular well-being. Materials and Methods: This comparative correctional study was conducted among forty-two healthy traffic police officers. The participants were divided into exercising and non-exercising groups based on their physical activity levels. Heart rate variability was measured using standard technique. Data was analysed using Microsoft Excel and SPSS version 16. The heart rate variability values were non parametric. So, data were expressed as median interquartile range and comparison between two groups was done with Mann-Whitney U test. p<0.05 was considered significant. Results: The results revealed that a higher proportion of traffic police officers were in the exercising group. Heart rate variability analysis showed significantly higher median values of RMSSD (58.42 ms vs. 41.30 ms), NN50 (80.00 vs. 24.00), pNN50% (36.56% vs. 11.820%) and HF power (1079.40 ms² vs. 368.000 ms²) in the exercising group. Additionally, the exercising group exhibited a lower LF/HF ratio (0.61 vs. 1.60). Although not statistically significant, heart rate was less in exercising group (73.61±6.93bpmvs. 72.93± 7.79bpm). Conclusion: The study suggests that even with prolonged workplace posture, exercise among traffic police can have higher heart rate variability and parasympathetic dominance, a positive indicator for cardiovascular health.

Intake of Dark and Milk Chocolate Differently Affects Autonomic Nervous Control of the Heart During Rest and Mental Stress

Objective Chocolate is a popular food that may affect the activity of the autonomic nervous system (ANS). The aim of this study was to determine the effect of a single dose of dark or milk chocolate on ANS cardiac control during rest and mental stress induced by the Stroop test (ST). Methods Healthy participants, divided into DARK or MILK chocolate groups, ingested corresponding type of chocolate (1 g/kg body weight). They underwent measurement of ANS during relaxation and ST before and 2 h after chocolate consumption. ANS control was assessed by determination of heart rate (HR) and heart rate variability using parameters related to complex autonomic modulation (TP, SDNN) or primary vagal modulation (HFnu, RMSSD). Results HR was always increased during ST in both groups. Relaxation HR values after chocolate ingestion were higher only in the DARK chocolate group. During ST, values of TP, SDNN and HFnu decreased before and after chocolate ingestion in the DARK group, but only before chocolate ingestion in the MILK group. RMSSD values decreased during ST before and after chocolate ingestion in both groups. Relaxation TP, RMSSD and HFnu values after chocolate ingestion were lower in the DARK but not in the MILK group. Conclusion The results suggest that even a single dose of milk chocolate attenuates changes in ANS cardiac control induced by mental stress, whereas a single dose of dark chocolate has an activating effect on the heart via modification of ANS cardiac control at rest. Different levels of sugars and cocoa biologically active compounds in the two types of chocolate could explain the observed effects.

Diurnal variation of heart rate variability in individuals with spinal cord injury

BackgroundHeart rate variability (HRV) may provide objective information about cardiogenic autonomic balance in individuals with spinal cord injury (SCI). The aim of this study was to characterize the diurnal variation of HRV in individuals with SCI at lesion level T6 and above and lesion level below T6.MethodsThis was a retrospective analysis of a prior cross-sectional study. Individuals with chronic SCI underwent 24 h recording of the time between consecutive R waves (RR interval) to derive parameters of HRV as follows: standard deviation of all normal-to-normal R–R intervals (SDNN) and square root of the mean of the squared differences between successive R–R intervals (RMSSD) (time domain); and high frequency power (HF), low-frequency power (LF), very low frequency power (VLF), ultra-low frequency power (ULF) and total power (TP) (frequency domain). Changes in the magnitude of HRV outcomes over the 24 h period were investigated using a novel multi-component cosinor model constrained to the form of a three-harmonic Fourier series.ResultsParticipants were grouped as lesion level T6 and above (n = 22) or below T6 (n = 36). Most of them were male (n = 40, 69%) and the median age (interquartile range) was 50.5 (28) years. Both groups exhibited similar diurnal patterns in most HRV metrics. The lowest values occurred in the late afternoon (4–6 pm) and gradually increased, peaking around midnight to early morning (1–6 am). Exceptions included RMSSD, which peaked before midnight, and ULF, which showed a double peak pattern that peaked from 11 am to 1 pm and 4–6 am in participants with lesion level at T6 and above. The HRV values in participants with lesion level T6 and above were generally lower than participants with lesion level below T6, except for peak values of RMSSD, HF and LF.ConclusionThis study demonstrated substantial diurnal variation of HRV in participants with SCI in both groups of participants. In clinical and research settings, diurnal variations in HRV must be taken into consideration.

Full-Term and Preterm Newborns Differ More Significantly in Photoplethysmographic Waveform Variability than Heart Rate Variability.

Features of cardiovascular autonomic regulation in infants are poorly studied compared with adults. However, the clinical significance of autonomic dysfunction in infants is very high. The goal of our research was to study the temporal and frequency-dependent features, as well as low-frequency synchronization in cardiovascular autonomic regulation in full-term vs. preterm newborns, based on the analysis of their heart rate variability (HRV) and photoplethysmographic waveform variability (PPGV). The study included three groups of newborns: 64 full-term newborns (with a gestational age at birth of 37-40 weeks) with a physiological course of the neonatal adaptation; 23 full-term newborns (with a gestational age at birth of 37-40 weeks) with a pathological course of the neonatal adaptation; and 17 preterm newborns (with a postconceptional age of 34 weeks or more). We conducted spectral analysis of HRV and PPGV, along with an assessment of the synchronization strength between low-frequency oscillations in HRV and in PPGV (synchronization index). We employed several options for the boundaries of the high-frequency (HF) band: 0.15-0.40 Hz, 0.2-2 Hz, 0.15-0.8 Hz, and 0.24-1.04 Hz. Preterm newborns had higher heart rate, RMSSD, and PNN50 values relative to both groups of full-term newborns. Values of SDNN index and synchronization index (S index) were similar in all groups of newborns. Differences in frequency domain indices of HRV between groups of newborns depended on the considered options of HF band boundaries. Values of frequency domain indices of PPGV demonstrated similar differences between groups, regardless of the boundaries of considered options of HF bands and the location of PPG signal recording (forehead or leg). An increase in sympathetic influences on peripheral blood flow and a decrease in respiratory influences were observed along the following gradient: healthy full-term newborns → preterm newborns → full-term newborns with pathology. Differences in frequency domain indices of autonomic regulation between the studied groups of newborns depended on the boundaries of the considered options of the HF band. Frequency domain indices of PPGV revealed significantly more pronounced differences between groups of newborns than analogous HRV indicators. An increase in sympathetic influences on peripheral blood flow and a decrease in respiratory influences were observed along the following gradient: healthy full-term newborns → preterm newborns → full-term newborns with pathology.

The Impact of Prenatal Alcohol Exposure on the Autonomic Nervous System and Cardiovascular System in Rats in a Sex-Specific Manner.

Fetal Alcohol Spectrum Disorder (FASD) is a consequence of prenatal alcohol exposure (PAE) associated with a range of effects, including dysmorphic features, prenatal and/or postnatal growth problems, and neurodevelopmental difficulties. Despite advances in treatment methods, there are still gaps in knowledge that highlight the need for further research. The study investigates the effect of PAE on the autonomic system, including sex differences that may aid in early FASD diagnosis, which is essential for effective interventions. During gestational days 5 to 20, five pregnant female Wistar rats were orally administered either glucose or ethanol. After 22 days, 26 offspring were born and kept with their mothers for 21 days before being isolated. Electrocardiographic recordings were taken on the 29th and 64th day. Heart rate variability (HRV) parameters were collected, including heart rate (HR), standard deviation (SD), standard deviation of normal-to-normal intervals (SDNN), and the root mean square of successive differences between normal heartbeats (RMSSD). Additionally, a biochemical analysis of basic serum parameters was performed on day 68 of the study. The study found that PAE had a significant impact on HRV. While electrolyte homeostasis remained mostly unaffected, sex differences were observed across various parameters in both control and PAE groups, highlighting the sex-specific effects of PAE. Specifically, the PAE group had lower mean heart rates, particularly among females, and higher SDNN and RMSSD values. Additionally, there was a shift towards parasympathetic activity and a reduction in heart rate entropy in the PAE group. Biochemical changes induced by PAE were also observed, including elevated levels of alanine transaminase (ALT) and aspartate aminotransferase (AST), especially in males, increased creatinine concentration in females, and alterations in lipid metabolism. PAE negatively affects the development of the autonomic nervous system, resulting in decreased heart rate and altered sympathetic activity. PAE also induces cardiovascular abnormalities with sex-specific effects, highlighting a relationship between PAE consequences and sex. Elevated liver enzymes in the PAE group may indicate direct toxic effects, while increased creatinine levels, particularly in females, may suggest an influence on nephrogenesis and vascular function. The reduced potassium content may be linked to hypothalamus-pituitary-adrenal axis overactivity.

Dynamics of heart rhythm disorders in combatants with acute myocarditis during a 6-month follow-up

The main factors of an unfavorable prognosis, are life-threatening heart rhythm disorders which determine the severity of the clinical course of myocarditis, in addition to impaired contractility and dilatation of the left ventricle (LV). The aim of the study was to assess the frequency and nature of arrhythmias and establish predictors of their long-term persistence, assess the severity of anxiety and depression, changes in heart rate variability in combatants on the background of changes in the structural and functional state of the left ventricle during a 6-month follow-up. The study included 52 male servicemen (combatants) with acute myocarditis (AM) with an average age of 33.4±2.5 years. All patients were assessed by Questionnaire according to the Hospital Anxiety and Depression Scale (HADS) and underwent 24 hour ECG monitoring, transthoracic echocardiography and cardiac magnetic resonance (CMR) with late enhancement using gadovist. At the onset of AM frequent supraventricular (30.7% of cases) and frequent ventricular (42.3% of cases) extrasystolic arrhythmia, as well as paroxysms of non-sustained ventricular tachycardia (26.9% of cases) on the background of heart rhythm variability disorders were recorded. After 6 months, there was an improvement in the structural and functional state of the heart, which was characterized by a decrease in dilatation and an improvement of LV systolic function, a decrease in the volume of the inflammatory lesion and the total number of affected LV segments revealed on cardiac MRI, which was associated with a decrease in the number of ventricular rhythm disorders and reduction of clinical manifestations of anxiety according to the HADS scale. The obtained data indicate that the persistence of supraventricular rhythm disorders is associated with the long-term presence of anxiety and low values of standard deviation of RR intervals (SDNN) and root mean square of successive differences between normal heartbeats (RMSSD). Also predictors of persistence of non-sustained ventricular tachycardia paroxysms were established – SDNN value ≤80.0 ms, LV end-diastolic volume index ≥95 ml/m2, total number of affected LV segments ≥6 segments, presence of delayed contrasting in ≥3 LV segments, pre­sence of ≥12 points on the HADS scale and predictors of atrial fibrillation – SDNN value ≤80.0 ms, RMSSD value ≤12.0 ms, total number of affected segments of LV≥6 seg. and ≥12 points on the HADS anxiety scale, determined at the onset of AM.

Yoga and Naturopathy intervention on psychological comorbidities and autonomic function for irritable bowel syndrome patient: A case study

Irritable bowel syndrome (IBS) is a common functional disorder of the gut-brain axis, characterized by abdominal pain and altered bowel habits. A 38-year-old male patient with a sedentary lifestyle, diagnosed with IBS based on Rome IV criteria, was underwent Yoga and Naturopathy interventions for one month in our outpatient department. The result showed a reduced Irritable Bowel Syndrome Severity Score (IBS-SSS) (315 to 109) and perceived stress (PSS) score (29 to 12) level. Heart rate variability (HRV) analysis showed increased SDNN (35.4 to 48.3 ms) and RMSSD (41.3 to 58.3 ms) values, indicative of improved HRV. Notably, parasympathetic dominance was observed, evidenced by increased pNN50% (14.56 to 18.41) and H.F (41.92 to 59.63 n.u) values, while the LF/HF ratio (1.381 to 0.675) decreased. This case report suggests that lifestyle change through Yoga and Naturopathic intervention is useful in the management of IBS with psychological co-morbidities .

A deep semi-supervised learning framework towards multi-output soft sensors development and applications in wastewater treatment processes

Soft sensors have emerged as a powerful tool for predicting quality-related but hard-to-measured variables in the wastewater treatment plants (WWTPs). However, due to high data dimensions and insufficient training data, many existing soft sensors usually suffer from low accuracy and degradation, and are unable to meet the field measurement requirements. To enhance the prediction performance and efficiency, this paper proposed a deep semi-supervised learning framework towards multi-output soft sensors in wastewater treatment processes. Firstly, a deep learning network is constructed by integrating stacked autoencoders with a multi-output neural network (SAE-MNN), which is used to eliminate redundant information from raw data and to predict multiple quality-related variables simultaneously. Secondly, the semi-supervised Co-training learning is extended to the multi-output systems and employed to address the challenge of insufficient training data. Two datasets collected from different WWTPs are provided to the effectiveness of the Co-training SAE-MNN framework, in terms of RMSSD values of 0.1073 and 0.1829, and the time consumption of 3.42 s and 12.54 s, respectively. The results demonstrate that the proposed soft sensor provides a reliable tool for multivariate prediction in WWTPs, and contributes to controlling detection costs and increasing wastewater treatment efficiency.

Experimental evaluation of ECG signal denoising methods based on HRV indices and their application in indoor thermal comfort study under different temperatures

The heart rate variability (HRV) features extracted from an electrocardiogram (ECG) signal have been widely used to help improve the performance of thermal comfort models, with the ECG signal denoising method being very important. In this study, 20 volunteers were recruited for experiments in a well-controlled chamber. Their ECG signals (a total of 6,000,000 sets of data) were collected under stable and variable temperature environments. With the use of the setup database, four denoising methods were compared: the fast Fourier transform (FFT), wavelet transform, Chebyshev filter, and Butterworth filter. When the performance of these methods was evaluated from ECG images, the Butterworth filter exhibited a more comprehensive and smoother representation of the original signal. Judging from denoising indices, the Butterworth filter exhibited the best performance, with its denoising indices surpassing those of fast Fourier transform and wavelet transform by differences ranging from 26% to 122%. Judging from HRV index and R-peak positioning, the data processed by Butterworth exhibited the highest reliability (93.5%), outperforming FFT (30.0%), the wavelet filter (72.5%), and the Chebyshev filter (78.5%). Furthermore, the 5th-order Butterworth filter exhibited the largest signal-to-noise ratio (SNR) with 1.1–34.4% larger and the smallest percent root-mean-square difference (PRD) with 15.2–66.1% smaller compared to other orders. Next, the characteristics of denoised HRV features under different temperatures were studied. During a temperature rise stage, the fitting R2 values of rMSSD, SDNN, and HR with temperature were 0.85, 0.64, and 0.78, respectively; meanwhile, during the subsequent temperature drop stage, the fitting R2 values were 0.78, 0.84, and 0.78, respectively. This suggests that changes in temperature can be effectively reflected by HRV indices. When gender was taken into consideration, the HR of females showed a 55.8% higher fitting level compared to males.

Detection of Early Cardiac Affection in Post-COVID Syndrome Using Heart Rate Variability and 2D Global Longitudinal Strain Echocardiographic Assessment of the Left Ventricle

Abstract Aim and objectives The aim of our study is to estimate the Heart Rate Variability (HRV) & two-dimensional global longitudinal strain (GLS) by speckle tracking echocardiography (2D STE) in post-COVID-19 patients after mild to moderate acute SARS COV-2 infection. Patients and Methods This study included fifty consecutive subjects between 17 & 82 years of age who were symptomatic after three weeks up to 3 months of experiencing mild to moderate COVID19 illness according to the CDC criteria of severity. Patients enrolled were coming for follow-up clinic visits at Ain Shams University Hospitals between June 2021- Jan2022. All patients had normal LVEF upon enrollment as assessed by M-mode and Modified Simpson's method. 2D Left Ventricular Global Longitudinal Strain (GLS) and 24-hours Holter monitoring were performed for all patients. Results The LVGLS and HRV were significantly impaired in the symptomatic post-COVID-19. LVGLS was below -16 in 20% of the patients while 22% were in the grey zone; between -18 and -16. SDNN was decreased (< 100 msec) in 24% of the patients. RMSSD values favored a mean below 40 msec with prevalence of 58% among the study population. LF/HF ratio was above 2 in 42% of the patients. Our research suggested a highly significant association between LVGLS and HRV; as 66.7% of patients with decreased SDNN had impaired LVGLS, as opposed to 33% who had normal LVGLS (p-value 0.000) Conclusion LVGLS measured by Speckle Tracking Echocardiography (STE) is an important bedside tool, alternative to CMR which is the gold standard, in assessing LV systolic functions post COVID-19. HRV can explain a lot of post- COVID symptoms attributed to dysautonomia. In our study, we targeted the patients having prolonged symptoms after COVID-19 illness, GLS and HRV were assessed trying to explain the cardiac involvement and if it is the cause of the so called" long COVID". We found high incidence of GLS impairment using STE as well as significant prevalence of diminished HRV. HRV (especially SDNN) and GLS were significantly correlated as 80% of the patients with impaired GLS had decreased SDNN (p-value 0.00).

Impact of Subarachnoid Hemorrhage on the Cardiac Autonomic Function During Rehabilitation in Children After Severe Traumatic Brain Injury.

This study aimed to investigate the impact of traumatic subarachnoid hemorrhage (tSAH) on cardiac autonomic control system (CACS) function in children after severe traumatic brain injury (TBI) during the subacute rehabilitation period. Thirty-three participants, 8-18 years of age, 42 (14-149) days after severe TBI at the beginning of the subacute rehabilitation, were included in the study. Six participants were diagnosed with tSAH during acute medical care (tSAH group). Heart rate variability (HRV) was assessed by the standard deviation of the N-N interval (SDNN) and the square root of the mean square differences of successive R-R interval (RMSSD) using a Polar RS800CX device while sitting at rest for 5 min. A second assessment was performed 8 weeks later. No significant difference between the tSAH and non-tSAH groups were found in the demographic and functional characteristics or injury severity. However, in comparison to the non-tSAH group, the tSAH group had lower SDNN (23.9 [10.5-47.3] vs. 43.9 [21.8-118.8], respectively; p = 0.005) and RMSSD values (11.8 [5.9-24.5] vs. 29.6 [8.9-71.7], respectively; p = 0.004). Neither group demonstrated changes in HRV values at rest in the second assessment, whereas the significant difference in SDNN (p = 0.035) and RMSSD (p = 0.008) remained. Children diagnosed with SAH after severe TBI presented poorer CACS function during the subacute rehabilitation. Given that reduced HRV values may be a marker for potential heart disease, the medical team should be aware of the influence of existing tSAH. Future studies with larger sample sizes and longer follow-up periods are warranted to further investigate this topic. ClinicalTrials.gov number: NCT03215082.

Effects of Post-awakening Light Exposure on Heart Rate Variability in Healthy Male Individuals

Light-induced effects on the autonomic nervous system (ANS) are assumed to be mediated by retinal projections to the hypothalamic suprachiasmatic nucleus (SCN) via different routes. Light information for the circadian system is detected by a subset of intrinsically photosensitive retinal ganglion cells (ipRGCs), however, inconsistency exists in research concerning the effects of light exposure on heart rate variability (HRV). Two within-subject experiments were conducted in a standardized sleep laboratory to investigate effects of light intensity (study I, n = 29: 2 days dim vs. bright light) and spectral composition (study II, n = 24: 3 days using red vs. blue vs. green light) on HRV parameters (RMSSD, LF, HF-HRV, LF/HF ratio). Light exposure was conducted for one-hour in the post-awakening phase at 5:00 AM. Results revealed no significant light intensity effect comparing dim light versus bright white light on HRV parameters. Light color of different wavelengths significantly influenced all HRV parameters except the low frequency, with moderate to large effect sizes. RMSSD values were elevated for all three colors compared to norm values, indicating stronger parasympathetic activation. LED light of different spectral compositions demonstrated bidirectional effects on spectral components of the HRV. Red light decreased the LF/HF ratio within 30 min, whereas with blue light, LF/HF ratio consistently increased across 40 min of light exposure.

Association of coronary artery calcium with heart rate variability in the Brazilian Longitudinal Study of Adult Health - ELSA-Brasil

Current data shows that the autonomic and vascular systems can influence each other. However, only a few studies have addressed this association in the general population. We aimed to investigate whether heart rate variability (HRV) was associated with coronary artery calcium (CAC) in a cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). We examined baseline data from 3138 participants (aged 35 to 74 years) without previous cardiovascular disease who underwent CAC score assessment and had validated HRV recordings. Prevalent CAC was defined as a CAC score>0, and HRV analyses were performed over 5-min segments. We detected CAC score>0 in 765 (24.4%) participants. Subgroup analyses in older participants (≥49 years) adjusted for sociodemographic and clinical variables revealed that CAC score>0 was associated with lower values of standard deviation of NN intervals (SDNN) (odds ratio [OR]=1.32; 95%CI: 1.05,1.65), root mean square of successive differences between adjacent NN intervals (RMSSD) (OR=1.28; 95%CI: 1.02,1.61), and low frequency (LF) (OR=1.53, 95%CI: 1.21,1.92). Interaction analysis between HRV indices and sex in age-stratified groups revealed significant effect modification: women showed increased OR for prevalent CAC in the younger group, while for men, the associations were in the older group. In conclusion, participants aged ≥49 years with low SDNN, RMSSD, and LF values were more likely to present prevalent CAC, suggesting a complex interaction between these markers in the pathogenesis of atherosclerosis. Furthermore, our results suggested that the relationship between CAC and HRV might be sex- and age-related.

The Hemisphere of the Brain in Which a Stroke Has Occurred Visible in the Heart Rate Variability.

The aim of this study was to assess whether heart rate variability (HRV) could predict which hemisphere of the brain was affected during an acute ischemic stroke (AIS). To achieve this goal, we compared HRV between patients with a right (RH) and left hemispheric (LH) stroke. The studied group consisted of 64 patients with AIS (25 with RH and 39 with LH stroke, with a mean age of 64 ± 12 and 66 ± 13, p = 0.3, respectively) using 24 h Holter ECG records at NN intervals performed at a mean of 4.3 ± 2 days following their AIS. Standard linear methods were used to analyze HRV in the time and frequency domains, as well as nonlinear methods, including sample entropy, detrended fluctuation analysis, and asymmetry measures. Patients with an LH stroke had significantly greater values for sample entropy compared to subjects with an RH stroke (1.31 ± 0.53 vs. 0.92 ± 0.46, p = 0.003, Bonferroni-corrected p = 0.033, effect size = 0.8). The LH stroke group also had higher RMSSD (113 ± 81 vs. 76 ± 61, p = 0.06), pNN50 (33.35 ± 28.54 vs. 18.52 ± 23.75, p = 0.02), and HFnu (48.42 ± 16.41 vs. 42.66 ± 17.88, p = 0.11) values, when compared to the RH group, which was possibly related to higher activity in the parasympathetic system in the LH group. Conversely, subjects with RH stroke had higher LFnu (57.34 ± 17.88 vs. 51.58 ± 16.41, p-value = 0.11) and LF/HF ratios (2.24 ± 2.87 vs. 1.68 ± 2.50, p-value = 0.11), which were likely related to higher activity in the sympathetic nervous system, when compared to the LH stroke group. Our pilot study demonstrated that patients with RH stroke had lower HRV complexity than those with LH stroke, indicating that HRV could be useful in the discrimination of hemispheric involvement in AIS.

Agreement between ultrashort-term and long-term heart rate variability based on 24-hour Holter monitoring

Abstract Introduction Heart rate variability (HRV) measured for 24 hours (long-term HRV) serves as the clinical gold standard in the risk stratification of patients with comorbidities such as myocardial infarction, stroke, multiple sclerosis, end stage renal disease, and diabetic neuropathy. Previous studies explored the utility of ultra-short (US) HRV, measured for less than five minutes which could be used for bedside prognostication, for future research, or as a cheaper diagnostic alternative. Purpose This study determined the agreement between US-HRV and long-term HRV based on 24-hour holter monitoring results at a tertiary Filipino hospital. It also found the agreement in the US-HRV and long-term HRV by time of day and condition, age, sex, comorbidities, and by ability to detect abnormal HRV. Methods Tracings of 24-hour holter monitoring from January 2017 and December 2019 were reviewed. Excluded from the study were those who had arrhythmias or were taking medications affecting the autonomic nervous system. Samples of three-minute excerpts were obtained at 7am (daytime, awake), 12nn (daytime, awake, with activity), 7pm (evening, awake), and 12mn (evening, asleep). RR intervals were measured and HRV through SDNN and RMSSD were determined. Interclass correlation coefficient and kappa statistic were used to analyze the agreement between values of US and long-term HRV. Bland-Altman plots were constructed, and the limits of agreement (LOA) were reported. Kappa statistic was used to determine the agreement between the two methods in detecting abnormal HRV. Results A total of 92 results were reviewed for this study, with most patients having hypertension. Results showed that US-HRV by SDNN underestimates HRV by 47.35 to 60.58 ms (mean difference). The average discrepancy was found to be highest during daytime, awake with activity. Meanwhile, US-HRV by RMSSD was found to overestimate HRV by −29.86 to −85.24 ms (mean difference). The average discrepancy was found to be highest during evening, awake. There is poor agreement between SDNN and RMSSD measured using long-term HRV and US-HRV in all four samples, even with age, gender, and comorbidities factored in. Likewise, there is poor agreement between US-HRV and long-term HRV values in detecting abnormal HRV. At best, evening US-HRV RMSSD values have moderate agreement in detecting abnormal US-HRV. However, the study was done in a less controlled environment. Also, long-term time-domain variables (RMSSD and SDNN) are known to reflect circadian rhythms and the overall change in the autonomic nervous system, hence three-minute measurements might poorly reflect changes occurring in the autonomic nervous systems. Conclusion There is poor agreement between three-minute US-HRV and long-term HRV obtained through 24-hour holter monitoring. Studies done in a more controlled environment are recommended. Funding Acknowledgement Type of funding sources: None.

Pre-partum HRV as a predictor of postpartum depression: The potential use of a smartphone application for physiological recordings

BackgroundThis study aimed to investigate the role of a time-domain Heart Rate Variability index (the root mean square of successive difference between NN intervals, rMSSD) as a predictor of the onset of postpartum depression. HRV has been related to an increased risk of depression in the general population. However, its role in pregnant women is not clear, and the potential use of smartphone applications to evaluate HRV in this population has not been investigated. MethodsIn study 1, simultaneous electrocardiogram and smartphone photoplethysmography were collected. The rMSSD was determined from each recording to evaluate the accuracy of a smartphone application in the measurement of HRV. In study 2, 135 pregnant women provided rMSSD values measured through a smartphone application in the prepartum (second or third trimester) and filled in the Edinburgh Postnatal Depression Scale in the postpartum (one month after the childbirth). ResultsStudy 1 showed the excellent accuracy of the smartphone application in the measurement of rMSSD. Study 2 indicated that lower prepartum rMSSD predicted higher depressive symptoms in the postpartum (β = −0.217, p = 0.010) after controlling for prepartum depressive symptoms and other potential covariates. LimitationsArtefacts (e.g., hand movements) might have corrupted the physiological signal registered. ConclusionThis study showed that a reduced vagal tone, indexed by lower rMSSD, during pregnancy was a predictor of depressive symptoms one month after childbirth. The prepartum period may offer an important timeframe to implement preventive intervention on vagal modulation in order to prevent depressive symptoms in the postpartum.

Effects of a Combined Intradialytic Exercise Training Program and Music on Cardiac Autonomic Nervous System Activity in Hemodialysis Patients.

This study aimed to examine the effect of an intradialytic exercise program in combination with music on heart rate variability (HRV) indices and functional capacity in patients on maintenance hemodialysis (HD). Methods: Forty HD patients were randomized to four training groups for six months: the combined music and exercise group (Group A), the exercise group (Group B), the music group (Group C), and the control group (Group D). At baseline and after 6 months, all participants underwent both short- (for 30 min) and long- (for 24 h) term measurements of HRV and functional capacity assessment with a 6 min walking test (6MWT). Patients of groups A and C listened to preferred music. Results: Long-term HRV analysis showed that standard deviation of all normal-to-normal RR intervals (SDNN) and the square root of the mean squared differences of successive RR intervals (rMSSD) were significantly higher at the end of the study in groups A (by 13.2% and 47.3%), B (by 15.1% and 50%), and C (by 9.0% and 30.1%), compared to group D (p < 0.05). Values of rMSSD and percentage of RR intervals differing by more than 50 ms from the preceding RR interval (pNN50) were elevated in groups A (by 35.6% and 142.9%), B (by 36.1% and 75%), and C (by 15.2% and 28.6%), compared to baseline measurements (p < 0.05). Also, pNN50 was increased in group A compared to groups B (by 21.4%), C (by 88.9%), and D (by 142.9%) (p < 0.05). Similar results were noted by short-term HRV analysis. Functional capacity was improved at the end of the 6-month study in groups A (by 20.3% and 25.7%) and B (by 15.8% and 21.1%) compared to groups C and D (p < 0.05). Conclusions: Intradialytic exercise combined with music-listening can improve the functional capacity and cardiac autonomic nervous system activity in hemodialysis patients.

Autonomic and cardiorespiratory responses to the active tilt test in individuals with Parkinson disease: cross-sectional study.

The Parkinson disease (PD) is frequently associated with autonomic dysfunctions. However, data regarding the influence of PD on the autonomic responses to postural changes is limited. To analyze and compare the autonomic responses, evaluated through linear and non-linear methods of heart rate variability, and cardiorespiratory parameters in two groups: Parkinson disease (PDG) and control (CG), at rest and during the active tilt test. A total of 48 participants were analyzed (PDG: n = 25;73.40 ± 7.01 years / CG: n = 23;70.17 ± 8.20 years). The autonomic modulation and cardiorespiratory parameters were evaluated at rest and during the active tilt test. To assess the autonomic modulation the linear indices, at the time (rMSSD, SDNN) and frequency (LF, HF, LF/HF) domains, and the non-linear indices, obtained through the Poincaré plot (SD1, SD2, SD1/SD2), were calculated. The cardiorespiratory parameters evaluated were heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP), peripheral oxygen saturation (SpO2), and respiratory rate. At rest, the PDG presented significantly lower values of rMSSD, SDNN, LF, HF, SD1, SD2, and DBP, and higher values of SpO2. During test, in the PD group, modifications were observed in HR, and SBP, besides a reduced parasympathetic response, and an increased global modulation. The qualitative analysis of the Poincaré plot showed that the PDG has a lower dispersion of the RR intervals during rest and the active tilt test. Individuals with PD present reduced global variability and parasympathetic modulation at rest, and reduced parasympathetic response and damage in HR regulation when performing the active tilt test, compared with controls.

HEART RATE VARIABILITY AND BRAIN FUNCTIONING IN HYPERTENSIVE PATIENTS

Objective: Decreased heart rate variability (HRV) reflecting autonomic nervous dysfunction has been associated with increased mortality in cardiovascular diseases. Less is known about the relationship between HRV and hypertension associated cognitive impairment. The study aimed to compare HRV parameters in well-controlled hypertensive patients with and without cognitive dysfunction, as marker of functional brain damage caused by hypertension. Design and method: Data about 226 hypertensive patients were obtained, 53% males, between 37 and 98 years (mean age 66 years ± 10). The mean blood pressure was 135/81 mmHg (±19/11 mmHg) (under hypertensive medication). Cognitive abilities were measured with the multi-domain Montreal Cognitive Assessment questionnaire (MoCA) defining cognitive decline below 24 points. All patients had 24- hour Holter monitoring. Time domain [pNN(50), NN(50) SDNN, rMSSD] and the LF/HF frequency domain HRV parameters were analyzed in patients with normal and impaired cognition, and in different cognitive domains with the IBM SPSS v20 software. Results: Cognitive dysfunction was present in 63.73% of the studied group. Time domain parameters pNN(50), NN(50) and r MSSD were significantly higher in patients with altered cognition (p = 0.002, p = 0.001, p = 0.02). Frequency domain HF was also significantly higher in this group (p = 0.03). Male individuals had significantly higher LF/HF ratio (men 1.08% vs. women 0.97%, p = 0.006). Patients with hypertension grade II had higher LF/HF ratio compared to grade III (1.069 vs. 0.98%, p = 0.01). Analyzes of cognitive domains in the total study group revealed low SDNN, rMSSD values in language, abstraction domains, with statistical significance in the domains of visuospatial-executive (SDNN p = 0.013, rMSSD p = 0.001) and attention (SDNN p = 0.044). Higher LF/HF ratio was found in all cognitive domains, excepting attention, with statistical difference in delayed recall (p = 0.015). Conclusions: Our data suggest a gender difference regarding sympathovagal balance in hypertensive patients with enhanced sympathetic activity in males. Although higher HRV was observed in cognitively impaired well-controlled hypertensive patients, time domain HRV parameters reflecting impaired autonomic nervous function were related to some specific cognitive domains. Future studies are needed to better understand these findings.

CARDIOVASCULAR RESPONSE OF ATHLETES UNDER DIFFERENT TRAINING CONDITIONS

ABSTRACT Introduction: Improving cardiovascular function is one of the main training goals of many sports. Objective: To understand the characteristics of the cardiovascular response of athletes under different training conditions. Methods: Thirty male basketball students were enrolled. The subjects were divided into A and B groups according to their years of training, with 15 students in each group. Exercise fatigue tests were performed, starting at a low intensity and gradually increasing the load to a relatively high degree of fatigue. Results: The RMSSD value was 42.82±31.41ms in group A and 46.48±35.26ms in group B undera low fatigue state. The LF/HF value of the athletes in group A was 2.86±1.47 and the LF/HF value of the athletes in group B was 2.94±1.68. The RMSSD value was 40.78±31.17ms and 32.37±36.42ms for groups A and B, respectively, undera high fatigue state. Conclusions: Athletes with more years of training can mobilize more cardiac reserves to meet the increase in exercise load in a fatigue state and have better autonomic nervous regulation in the process of reaching a higher degree of fatigue state. Level of evidence II; Therapeutic studies - investigation of treatment results.