Changes In Heart Rate Variability Research Articles

Modifications of long-term heart rate variability produced in an experimental model of diet-induced metabolic syndrome.

Metabolic syndrome (MetS) has been linked to a higher prevalence of cardiac arrhythmias, the most frequent being atrial fibrillation, but the mechanisms are not well understood. One possible underlying mechanism may be an abnormal modulation of autonomic nervous system activity, which can be quantified by analysing heart rate variability (HRV). Our aim was to investigate the modifications of long-term HRV in an experimental model of diet-induced MetS to identify the early changes in HRV and the link between autonomic dysregulation and MetS components. NZW rabbits were randomly assigned to control (n = 10) or MetS (n = 10) groups, fed 28 weeks with high-fat, high-sucrose diet. 24-hour recordings were used to analyse HRV at week 28 using time-domain, frequency-domain and nonlinear analyses. Time-domain analysis showed a decrease in RR interval and triangular index (Ti). In the frequency domain, we found a decrease in the low frequency band. Nonlinear analyses showed a decrease in DFA-α1 and DFA-α2 (detrended fluctuations analysis) and maximum multiscale entropy. The strongest association between HRV parameters and markers of MetS was found between Ti and mean arterial pressure, and Ti and left atrial diameter, which could point towards the initial changes induced by the autonomic imbalance in MetS.

Cardiorhythm in postural changes depending on the autonomic centers reactivity

Postural changes are accompanied by the formation of an adaptive response of the cardiovascular system. This is manifested by a change in heart rate variability. The features of the reaction largely depend on the excitability (reactivity) of the vegetative centers. The aim of the study was to identify individual features of heart rate regulation in postural changes depending on the reactivity of sympathetic and parasympathetic autonomic centers in students. Material and Methods. In 50 men, temporal, frequency, geometric and calculated indicators of heart rate variability were determined in a horizontal position, with active orthostasis, passive orthostasis and passive antiorthostasis. The reactivity of the sympathetic system was assessed by the change of heart rate in active orthostasis. The reactivity of the parasympathetic system was determined by K30:15. Results and Discussion. With normal and high sympathetic reactivity, active orthostasis causes an increase in the low-frequency power of the spectrum, stress index, heart rate, a decrease in the high-frequency component and the duration of cardiac intervals. The changes are more pronounced with high sympathetic reactivity. In passive orthostasis, high sympathetic reactivity is manifested by a large increase in heart rate, shortening of cardiac intervals and a decrease in the proportion of the spectrogram high-frequency component. Passive antiorthostasis with normal sympathetic reactivity causes a decrease in the adequacy of the regulation processes and an expansion of the scatterogram. In subjects with high parasympathetic reactivity with active orthostasis, the increase in the stress index is less than with normal and low reactivity. With low parasympathetic reactivity, the indicator of the adequacy of the regulation processes is greater than with normal and high reactivity, and the increase in heart rate and shortening of the minimum cardiac interval is greater than with normal. In passive orthostasis, the proportion of the high-frequency component decreases, the proportion of the ultra-low-frequency component increases, the modal cardiointerval shortens, which is more pronounced with low parasympathetic reactivity than with normal. In passive antiorthostasis, the ultra-low frequency component decreases in individuals with normal reactivity. With high reactivity, the maximum value of the high-frequency component increases and the adequacy of the regulation processes decreases. Conclusion. Active and passive orthostasis is accompanied by activation of sympathetic centers. It is more pronounced with high reactivity of the sympathetic department and low reactivity of the parasympathetic. Passive antiorthostasis stimulates the activity of parasympathetic cardiac centers in subjects with normal, high parasympathetic reactivity and normal sympathetic reactivity.

Behavioral observations, heart rate and heart rate variability in horses following oral administration of a cannabidiol containing paste in three escalating doses (part 1/2).

Cannabidiol (CBD) products have been proposed to exert stress- and anxiety-relieving effects in animals. Despite the increasing popularity of CBD for veterinary use, the available research detailing the effects of CBD in horses is limited. The aim of this study (part 1 of 2) was to analyze stress parameters via behavioral observations and heart rate monitoring in healthy horses following single oral administration of a CBD containing paste in different doses. Study products were two pastes for oral administration, one containing CBD and one containing no active ingredient. Pastes were applied as single administrations in consecutive trials with escalating dosages (doses: 0.2, 1.0, 3.0 mg CBD/kg) to a treatment (trial 1: n = 3, trial 2: n = 3, trial 3: n = 5 horses) and a control group (trial 1: n = 3, trial 2: n = 3, trial 3: n = 6 horses) with minimum wash-out periods of seven days in between. Behavioral parameters were evaluated using video recordings to score the levels of sedation including the horses' reactions to acoustic and visual stimuli. Facial expression was assessed using photographs. Evaluation was based on the previously described facial sedation scale for horses (FaceSed) and the Horse Grimace Scale. For baseline values, identical observations were recorded on the day before each paste administration. Both paste administration and behavioral evaluation were performed double blinded. Cardiac beat-to-beat (R-R) intervals were continuously recorded throughout the trial and assessed using heart rate and heart rate variability parameters. Statistical analysis included comparison between treatment and control group over escalating doses and time points using linear mixed models. The CBD paste was well tolerated, and no side effects were observed. Analysis of sedation scores and facial expressions did not indicate significant differences between treatment and control group over the escalating doses. The heart rate was neither reduced, nor were significant changes in heart rate variability observed compared to the control group. Main limitation of this study is the small sample size. Further research is required to determine adequate doses and indications for the use of CBD products in horses.

Acute Effect of Positive Airway Pressure on Heart Rate Variability in Obstructive Sleep Apnea.

Autonomic dysregulation is associated with cardiovascular consequences in obstructive sleep apnea (OSA). This study aimed to investigate the effect of acute continuous positive airway pressure (CPAP) treatment on autonomic activity and to identify factors contributing to heart rate variability (HRV) changes in OSA. Frequency domain HRV parameters were calculated and compared between the baseline polysomnography and during the CPAP titration in 402 patients with moderate to severe OSA. There were significant reductions in total power, very low-frequency band power, low-frequency band power, and high-frequency band power during the CPAP titration as compared to the baseline polysomnography. This tendency was pronounced in male patients with severe OSA. Multivariate analysis found that changes in the apnea-hypopnea index and oxygen saturation were significantly associated with changes in sympathetic and parasympathetic activity, respectively. This study demonstrated that HRV parameters significantly changed during the CPAP titration, indicating a beneficial effect of CPAP in the restoration of sympathetic and parasympathetic hyperactivity in OSA. Prospective longitudinal studies should determine whether long-term CPAP treatment aids in maintaining the long-lasting improvement of the autonomic functions, thereby contributing to the prevention of cardiovascular and cerebrovascular diseases in patients with OSA.

The peculiarities of changes in myocardial electrical activity and heart rate variability in patients with coronary artery disease depending on the stage of concomitant iron deficiency

The aim of the study: to assess changes in myocardial electrical activity and heart rate variability (HRV) in patients with coronary artery disease (CAD) depending on the stage of iron deficiency (ID) and identify their relationship with ferrokinetic parameters. Materials and methods. In total, 90 patients with CAD, stable angina II–III FC were examined (men – 35, women – 55, age – 69 (61; 72) years). The patients were divided into 4 groups: the 1st group (n = 16) consisted of patients with concomitant ID anemia (IDA) of mild and moderate severity, the 2nd (n = 15) – with latent ID, the 3rd (n = 14) – with functional ID, the 4th (n = 45) – patients with CAD without iron metabolism disorders. The HRV features during 24 hours, daytime and nighttime as well as their relationships with ferrokinetic and hematological parameters were analyzed. The data analysis was performed using Statistica 13.0. Results. CAD patients with concomitant IDA demonstrated a tendency to have a higher average daytime heart rate value (U = 14.0; p ≈ 0.08), a longer duration of tachycardia (U = 20.0; p ≈ 0.06), and a significantly greater number (2.4 times) of ventricular extrasystoles (VE) (U = 7.0; p < 0.05) compared to patients without iron metabolism disorders. There were no statistically significant differences in heart rate, episodes of tachycardia, and the number of arrhythmic events in CAD patients with different stages of ID. During the temporal analysis of HRV indicators, patients with different stages of concomitant ID demonstrated a decrease in overall HRV due to SDNN-index, rMSSD (%) and HRVT triangular index both in active and passive periods as compared to patients without iron metabolism disorders. Spectral analysis of HRV has revealed reduced parasympathetic activity of the autonomic nervous system due to HF indicator in patients of the 1st–3rd groups. The presence of concomitant IDA was characterized by maximum changes in HRV indicators and the predominance of central mechanisms of HRV regulation over autonomic ones, which was confirmed by a significant increase in the centralization index (IC) and stress index (SI). For CAD patients with concomitant IDA and latent ID, a number of relationships between ferrokinetic and HRV parameters was found. There were no statistically significant correlations between indicators of iron metabolism and HRV in patients with CAD and functional ID. Conclusions. The decrease in iron stores in the body due to its tissue and transport reserves is accompanied by changes in the myocardial electrical activity, a progressive reduction in heart rate variability, autonomic dysfunction towards a suppression of the parasympathetic domain activity, confirming the relevant correlations with the ferrokinetic parameters.

Heart Rate and Heart Rate Variability in Healthy Preterm-Born Young Adults and Association with Vitamin D: A Wearable Device Assessment.

Prematurity has been associated with impaired parasympathetic cardiac regulation later in life. Changes in heart rate (HR) and heart rate variability (HRV) may indicate a risk for future cardiac dysfunction. The putative role of Vitamin D on cardiac autonomic function in individuals born preterm (PT) remains unknown. This study involves monitoring autonomic cardiac regulation and Vitamin D concentrations in 30 PT and 16 full-term (FT) young adults in a free-living context. The PT subjects were born between 1994 and 1997 at Oulu University Hospital. The inclusion criteria were (1) being born ≤ 32 gestation weeks or (2) being born < 34 gestation weeks with a birth weight under 1500 g. Participants wore an Oura ring sleep tracer, a smart ring device, for 2 weeks to monitor cardiac autonomic function. Parameters related to autonomic cardiac regulation, lowest nighttime resting HR, and the root mean square of successive differences (RMSSD) to describe HRV were collected. PT males exhibited a tendency toward lower RMSSD (71.8 ± 22.6) compared to FT males (95.63 ± 29.0; p = 0.10). Female participants had a similar mean RMSSD in the FT and PT groups at 72.04 ± 33.2 and 74.0 ± 35.0, respectively. Serum 25-hydroxyvitamin D concentration did not correlate with cardiac autonomic function parameters. When assessing the lowest resting nighttime HRs and HRVs in a long-term, real-world context, healthy female PT young adults performed similarly to their FT peers. In contrast, the present study's results suggest that male PT young adults exhibit impaired autonomic cardiac function, potentially putting them at risk for cardiovascular disease later in adulthood.

Early heart rate variability changes during acute fetal inflammatory response syndrome: An experimental study in a fetal sheep model.

Fetal infection during labor with fetal inflammatory response syndrome (FIRS) is associated with neurodevelopmental disabilities, cerebral palsy, neonatal sepsis, and mortality. Current methods to diagnose FIRS are inadequate. Thus, the study aim was to explore whether fetal heart rate variability (HRV) analysis can be used to detect FIRS. In chronically instrumented near-term fetal sheep, lipopolysaccharide (LPS) was injected intravenously to model FIRS. A control group received saline solution injection. Hemodynamic, blood gas analysis, interleukin-6 (IL-6), and 14 HRV indices were recorded for 6 h. In both groups, comparisons were made between the stability phase and the 6 h following injection (H1-H6, respectively) and between LPS and control groups. Fifteen lambs were instrumented. In the LPS group (n = 8), IL-6 increased significantly after LPS injection (p < 0.001), confirming the FIRS model. Fetal heart rate increased significantly after H5 (p < 0.01). In our FIRS model without shock or cardiovascular decompensation, five HRV measures changed significantly after H2 until H4 in comparison to baseline. Moreover, significant differences between LPS and control groups were observed in HRV measures between H2 and H4. These changes appear to be mediated by an increase of global variability and a loss of signal complexity. As significant HRV changes were detected before FHR increase, these indices may be valuable for early detection of acute FIRS.

Retracted: Changes of Short-Term Heart Rate Variability and Vertebral Artery Magnetic Resonance Angiography in Patients with Cervical Vertigo

Retracted: Changes of Short-Term Heart Rate Variability and Vertebral Artery Magnetic Resonance Angiography in Patients with Cervical Vertigo

Heart rhythm complexity analysis in patients with inferior ST-elevation myocardial infarction

Heart rhythm complexity (HRC), a subtype of heart rate variability (HRV), is an important tool to investigate cardiovascular disease. In this study, we aimed to analyze serial changes in HRV and HRC metrics in patients with inferior ST-elevation myocardial infarction (STEMI) within 1 year postinfarct and explore the association between HRC and postinfarct left ventricular (LV) systolic impairment. We prospectively enrolled 33 inferior STEMI patients and 74 control subjects and analyzed traditional linear HRV and HRC metrics in both groups, including detrended fluctuation analysis (DFA) and multiscale entropy (MSE). We also analyzed follow-up postinfarct echocardiography for 1 year. The STEMI group had significantly lower standard deviation of RR interval (SDNN), and DFAα2 within 7 days postinfarct (acute stage) comparing to control subjects. LF power was consistently higher in STEMI group during follow up. The MSE scale 5 was higher at acute stage comparing to control subjects and had a trend of decrease during 1-year postinfarct. The MSE area under scale 1–5 showed persistently lower than control subjects and progressively decreased during 1-year postinfarct. To predict long-term postinfarct LV systolic impairment, the slope between MSE scale 1 to 5 (slope 1–5) had the best predictive value. MSE slope 1–5 also increased the predictive ability of the linear HRV metrics in both the net reclassification index and integrated discrimination index models. In conclusion, HRC and LV contractility decreased 1 year postinfarct in inferior STEMI patients, and MSE slope 1–5 was a good predictor of postinfarct LV systolic impairment.

Phenotyping the autonomic nervous system in pregnancy using remote sensors: potential for complication prediction.

Objectives: The autonomic nervous system (ANS) plays a central role in dynamic adaptation during pregnancy in accordance with the pregnancy demands which otherwise can lead to various pregnancy complications. Despite the importance of understanding the ANS function during pregnancy, the literature lacks sufficiency in the ANS assessment. In this study, we aimed to identify the heart rate variability (HRV) function during the second and third trimesters of pregnancy and 1 week after childbirth and its relevant predictors in healthy pregnant Latina individuals in Orange County, CA. Materials and methods: N = 16 participants were enrolled into the study from which N = 14 (N = 13 healthy and n = 1 complicated) participants proceeded to the analysis phase. For the analysis, we conducted supervised machine learning modeling including the hierarchical linear model to understand the association between time and HRV and random forest regression to investigate the factors that may affect HRV during pregnancy. A t-test was used for exploratory analysis to compare the complicated case with healthy pregnancies. Results: The results of hierarchical linear model analysis showed a significant positive relationship between time (day) and average HRV (estimated effect = 0.06; p < 0.0001), regardless of being healthy or complicated, indicating that HRV increases during pregnancy significantly. Random forest regression results identified some lifestyle and sociodemographic factors such as activity, sleep, diet, and mental stress as important predictors for HRV changes in addition to time. The findings of the t-test indicated that the average weekly HRV of healthy and non-healthy subjects differed significantly (p < 0.05) during the 17weeks of the study. Conclusion: It is imperative to focus our attention on potential autonomic changes, particularly the possibility of increased parasympathetic activity as pregnancy advances. This observation may challenge the existing literature that often suggests a decline in parasympathetic activity toward the end of pregnancy. Moreover, our findings indicated the complexity of HRV prediction, involving various factors beyond the mere passage of time. To gain a more comprehensive understanding of this dynamic state, future investigations should delve into the intricate relationship between autonomic activity, considering diverse parasympathetic and sympathetic metrics, and the progression of pregnancy.

Interpreting regenerated post-industrial lands as green spaces: Comparing public perceptions of post-industrial landscapes using human factor design framework

Urban green spaces shaped by the post-industrial landscape possess distinctive characteristics and aesthetic features due to the exceptional properties of industrial remains. Previous studies have indicated that various types of urban green spaces without industrial remains, such as urban parks, waterfronts, and streets, have a positive impact on the public's physiological and psychological well-being. However, the extent and mechanisms of the public's response to post-industrial landscapes remain unclear. To investigate mechanisms of public perceptions of and preferences for post-industrial landscape types and elements, we conducted quantitative analysis by coupling multimodal data and comparative or difference analyses among urban green spaces. We conducted a randomized controlled experiment with 48 participants who viewed images of different combinations of post-industrial landscapes in a distraction-free environment. After a pause, Positive-Negative perception and Preference questionnaires were completed. Eye tracking data were recorded during the experiment. Changes in electrodermal activity and heart rate variability were used to measure physiological stress. This study employed Pearson's correlation model to examine the relationships between objective data and subjective data. The ANOVA test was utilized to investigate the variability of objective and subjective data across different groups. Additionally, a multiple-stepwise regression model was employed to analyze the specific influencing factors and their respective degrees of influence. We found that (1) artificial landscape elements in post-industrial landscapes were more appealing to participants and heightened their sense of stress; natural landscape elements can alleviate stress and promote restoration. (2) The percentage of flowering shrub and tree elements was significantly positively correlated with preference, while the percentage of ground-covering plant elements was significantly negatively correlated with preference. (3) Industrial construction was significantly positively correlated with the sense of historical value while industrial construction and pavement elements negatively correlated with preference. However, pavement elements significantly mitigated the sense of insecurity, poor accessibility, and pollution risk. (4) Industrial construction and pavement distinguished the post-industrial landscape from other green spaces without industrial remains while maximizing historical value and curiosity helped increase positive effects. Although impact mechanisms of natural elements in other green spaces without industrial remains showed homogeneous similarities, the scene composed of industrial mixed with natural elements may lead to different perceptions. Our findings indicate that multimodal data coupled with comparative analysis of multiple green space types can help to fully identify mechanisms by which landscape types and elements influence public perceptions and preferences. This understanding can help increase public satisfaction with post-industrial landscapes and enable researchers to determine the sustainability of post-industrial sites using interrogative design.

Changes in Heart Rate Variability During Low-Frequency Transcutaneous Electrical Nerve Stimulation in Athletes with Acute Musculoskeletal Injury

Background: Pain is a relevant clinical symptom to ask for medical management. Since pain is a subjective sensation, its intensity is difficult to precisely assess. Objectives: The present study aimed to determine whether heart rate variability (HRV) can be a potential parameter to evaluate the pain-relieving effect of low-frequency transcutaneous electrical nerve stimulation (TENS). Methods: Athletes with lower limb musculoskeletal injuries were voluntarily included in the study. Pressure pain thresholds (PPT) was measured immediately after the intervention, and 24 hours after the treatment. Heart rate variability was also determined from electrocardiography (ECG) monitoring throughout the intervention. Results: The HRV of 25 participants revealed that 30 minutes of low-frequency electrical stimulation immediately increased PPT (before = 2.67 ± 0.79; after = 2.92 ± 0.90, P = 0.011). Thirteen participants had more than a 10% increase in PPT after the intervention; nevertheless, three participants had a decrease in PPT. The PPT was returned to the baseline 24 hours after the intervention. Electrocardiography demonstrated that only the frequency domain of low frequency-high frequency (LF/HF) ratio was significantly increased after the intervention (before = 1.454 ± 0.739; after = 1.922 ± 1.378; P = 0.035) but not time-domain HRV. Time-domain HRV significantly decreased during the intervention before returning to the baseline. The correlation between the change in PPT is mostly correlated with LF/HF. Conclusions: Heart rate variability revealed the potential change in sympathovagal balance toward the sympathetic domain during low-frequency TENS intervention. The frequency-domain LF/HF ratio was the most sensitive parameter to be affected by pain.

Wearable Devices to Diagnose and Monitor the Progression of COVID-19 Through Heart Rate Variability Measurement: Systematic Review and Meta-Analysis.

Recent studies have linked low heart rate variability (HRV) with COVID-19, indicating that this parameter can be a marker of the onset of the disease and its severity and a predictor of mortality in infected people. Given the large number of wearable devices that capture physiological signals of the human body easily and noninvasively, several studies have used this equipment to measure the HRV of individuals and related these measures to COVID-19. The objective of this study was to assess the utility of HRV measurements obtained from wearable devices as predictive indicators of COVID-19, as well as the onset and worsening of symptoms in affected individuals. A systematic review was conducted searching the following databases up to the end of January 2023: Embase, PubMed, Web of Science, Scopus, and IEEE Xplore. Studies had to include (1) measures of HRV in patients with COVID-19 and (2) measurements involving the use of wearable devices. We also conducted a meta-analysis of these measures to reduce possible biases and increase the statistical power of the primary research. The main finding was the association between low HRV and the onset and worsening of COVID-19 symptoms. In some cases, it was possible to predict the onset of COVID-19 before a positive clinical test. The meta-analysis of studies reported that a reduction in HRV parameters is associated with COVID-19. Individuals with COVID-19 presented a reduction in the SD of the normal-to-normal interbeat intervals and root mean square of the successive differences compared with healthy individuals. The decrease in the SD of the normal-to-normal interbeat intervals was 3.25 ms (95% CI -5.34 to -1.16 ms), and the decrease in the root mean square of the successive differences was 1.24 ms (95% CI -3.71 to 1.23 ms). Wearable devices that measure changes in HRV, such as smartwatches, rings, and bracelets, provide information that allows for the identification of COVID-19 during the presymptomatic period as well as its worsening through an indirect and noninvasive self-diagnosis.

Visual and non-visual responses of drivers to simulated LED headlights varying in correlated colour temperature

This study aimed to investigate the impact of automotive headlights of different correlated colour temperatures (CCT) on the visual and non-visual performance of drivers. Forty drivers participated in the study, driving in a simulated night road for 45 min in three sessions. The LED headlights had CCTs of 3176 K, 4358 K and 6923 K, with an illuminance of 5 lx perpendicular to the participants’ eyes. Heart rate variability (HRV), psychomotor vigilance task and Karolinska sleepiness scale were measured before and after driving. At the end of the trials, achromatic far and near visual acuity tests, as well as achromatic far and near contrast sensitivity tests, were conducted. The study revealed that CCT did not affect achromatic far and near visual acuity. However, CCT had an impact on achromatic near and far contrast sensitivity, with higher CCT resulting in improved achromatic contrast sensitivity. As the CCT decreased, participants exhibited increased reaction time, made more errors, and reported higher sleepiness. The most significant physiological changes in HRV, including alterations in low frequency (LF), high frequency (HF) and LF/HF, were observed at lower CCT. The findings of this study suggest that both the visual and non-visual performance of drivers were enhanced when high CCTs were used for automotive LED headlights.

Anthracycline's Effects on Heart Rate Variability in Children with Acute Lymphoblastic Leukemia: Early Toxicity Signs-Pilot Study.

Anthracycline treatments are known to cause cardiotoxic long-term side effects in cancer survivors. Recently, a decrease in heart rate variability (HRV) has been identified in these patients, signaling autonomic dysfunction and altered cardiac fitness. This study aimed at evaluating changes in HRV in children treated with anthracyclines. A total of 35 pediatric patients with acute lymphoblastic leukemia were evaluated by means of a 24 h Holter ECG, at baseline and after reaching half the total cumulative dose of doxorubicin equivalent (120 mg/m2). Parameters of HRV were assessed, as well as any arrhythmic episodes, bradycardia and tachycardia percentages. The results showed a significant decrease in both time-domain and frequency-domain HRV parameters, following anthracycline treatment. The low-frequency (LF) to high-frequency (HF) parameters' ratio also displayed a significant difference (p = 0.035), suggestive of early cardiac autonomic dysfunction. Of note, none of the patients presented symptoms of heart disease or elevated troponins, and only two patients presented echocardiographic signs of diastolic dysfunction. The present study showed that cardiac autonomic nervous system regulation is compromised in children treated with anthracyclines even before reaching the total cumulative dose. Therefore, HRV parameters could be the first indicators of subclinical cardiac toxicity, making Holter ECG monitoring of the oncological patient a necessity.

Modifications of short-term heart rate variability in metabolic syndrome: a systematic review and meta-analysis

Abstract Introduction Metabolic syndrome (MS) is a clinical condition in which different non-communicable chronic diseases converge, such as hypertension, diabetes, dyslipidemia and obesity. MS has been related to dysregulation of the autonomic nervous system (ANS). Heart rate variability (HRV) has been widely used as a tool to assess the activity of autonomic function, which could be very useful for diagnosis or monitoring in patients with MS; however, to date, no quantitative analysis of ANS dysfunction in MS has been performed. For this reason, the objective of this systematic review and meta-analysis (MA) is to determine the impact that MS produces in short-term HRV, characterizing the cardiac autonomic dysfunction induced by this pathological condition and the most frequently reported explanatory variables. Methods We searched PubMed, Web of Science and Scopus electronic databases for original works with short-term HRV recordings (15 minutes or shorter) that compared people with MS (MS+) versus healthy people as a control group (MS-). The search was carried out between June 25th, 2022 and September 1st, 2022. Within these databases, the terms used were "metabolic syndrome" linked to "heart rate variability" (HRV), "cardiac autonomic control", "cardiac autonomic function", or "cardiac autonomic modulation". This systematic review and MA was performed according with PRISMA guidelines and registered at the International Prospective Register of Systematic Reviews. Results are reported as standard mean difference [95% CI]. Results Twenty-eight articles were included in the qualitative synthesis and nineteen of them met required criteria to be included in the MA. MS decreased SDNN (-0.40 [-0.5, -0.3], p&amp;lt;0.001), rMSSD (-7.59 [-9.98, -5.19], p&amp;lt;0.001), HF (-0.32 [-0.46, -0.18], p&amp;lt;0.001) and LF (-0.22 [-0.39, -0.06], p&amp;lt;0.01). The ratio LF/HF did not change (0.24 [-0.22, 0.69]). In subsequent subanalyses, we found a decreased in SDNN (-0.99 (-1.45, -0.52], p&amp;lt;0.001), rMSSD (-10.18 [-16.85, -3.52], p&amp;lt;0.01) and HF (-1.04 [-1.97, -0.1] p&amp;lt;0.05) in women. In men, only LF showed a significant decrease (-0.26 [-0.5, -0.2], p&amp;lt;0.05). We could not perform MA for the non-linear variables, but the qualitative analyses showed a decrease in SD1 and increase in SD2 of the Poincare-plot for the MS group. Conclusions MS produced changes in short-term HRV in the time-domain analyses, showing a decrease of SDNN and rMSSD. Regarding the frequency-domain analyses, MS induced a decrease in HF and LF, with the exception of the LF/HF relationship, which was not modified. When gender was taken into account, the MA was only possible in one of both genders (men or women) in rMSSD and LF/HF. Lastly, when data for both men and women were available, gender subanalyses showed a different behavior than the mixed analyses for SDNN, HF and LF, which might point towards a different impact of MS in men and women.

Metabolic syndrome and long-term heart rate variability: a systematic review and meta-analysis

Abstract Introduction Metabolic syndrome (MS) is defined as the convergence over time of a group of non-communicable chronic diseases (hypertension, diabetes, dyslipidemia, obesity). There is agreement that MS is related to pathological changes in the behavior of the autonomic nervous system (ANS). Heart rate variability (HRV) is a very useful tool for assessing autonomous behavior, widely used and that could be useful for the diagnosis and monitoring of MS. However, to date, there are no quantitative analyses using meta-analysis (MA) that have addressed the changes that MS causes on the ANS. Therefore, the objective of this systematic review and MA is to evaluate changes in long-term HRV in patients with MS, in order to characterize the cardiac autonomic dysfunction induced by this pathological condition and the most frequently reported explanatory variables. Methods We searched PubMed, Web of Science and Scopus electronic databases for original works with long-term HRV recordings (24-h holter) that compared people with MS (MS+) versus healthy people as a control group (MS-). The search was carried out between June 25th, 2022 and September 1st, 2022. In the databases selected, the terms used were "metabolic syndrome" linked to "heart rate variability" (HRV), "cardiac autonomic control", "cardiac autonomic function", or "cardiac autonomic modulation". This systematic review and MA was performed according with PRISMA guidelines and registered at the International Prospective Register of Systematic Reviews (CRD42022358975). Results are reported as standard mean difference [95% CI]. Results Thirteen articles were included in the qualitative synthesis and seven of them met required criteria to be included in the MA. MS decreased SDNN (-0.33 [-0.57, -0.09], p=0.008), LF (-0.40 [-0.51, -0.28], p&amp;lt;0.0001), VLF (-0.35 [-0.50, -0.21], p p&amp;lt;0.0001)) and TP (-0.24 [-0.43, -0.05], p=0.01). The MA did not find significant differences in rMSSD (-0.09 [-0.31, 0.13], p=0.41), HF (-0.29 [-0.61, 0.03], p=0.07) and LF/HF (-0.04 [-0.45, 0.36], p=0.84). No article reported information by gender. In the case of the non-linear variables, the information reported was not enough to carry out the MA, but the qualitative analyses showed no change in SD1 of the Poincare plot and a decrease in the multiscale entropy. For the SD2 of the Poincare plot and alfa-1 of the detrended fluctuation analyses, the results are not conclusive. Conclusions The analysis of HRV (time-domain) in long recording periods showed that patients with MS have lower values in the SDNN and no significant changes in rMSSD. Regarding the frequency domain analysis, we found that MS induced a significant decrease in LF, VLF and TP. The MA did not show changes in HF and LF/HF, and quantitative analyses of non-linear parameters could not be performed.

Abstract 13175: Association of Heart Rate Variability and Electrolyte Changes During Hemodialysis in Patients With Chronic Kidney Disease

Introduction: Autonomic neuropathy commonly arises as a long-term complication in chronic kidney disease (CKD) and can be diagnosed from heart rate variability (HRV), calculated from electrocardiogram (ECG) recordings. Hypothesis: There is limited data about HRV using real-time ECG according to electrolyte levels during hemodialysis (HD) in patients with CKD. Methods: Total of 50 patients (62.1±10.7 years) with CKD underwent continuous real-time ECG monitor (237.4±15.3 mins) during HD for HRV using remote monitoring system and checked electrolyte levels before/after HD. And we compared HRV according to electrolyte levels. Results: During the monitor, we checked total 2374 times of ECG and electrolyte level simultaneously of all patients. Both time and frequency domain HRV were higher when the patients had lower K + level change before/after HD (&lt;0.5mEq/L) as compared with those with higher K + level change (&gt;0.5mEq/L) in Table. In addition, there were higher incidence of arrhythmic events including atrial/ventricular premature complexes, even though no difference of mean heart rate in patients with lower K+ level change group (P&lt;0.001). Conclusions: Poor controlled K+ level during hemodialysis was independently associated with higher HRV in patients with CKD. This is further substantiated by independent continuous associations between real-time measures of K+ level and higher HRV. These data strongly suggest that cardiac autonomic dysfunction can be caused by lower change before/after hemodialysis alone.

The effectiveness of time domain and nonlinear heart rate variability metrics in ultra-short time series.

Ultra short-term (UST) heart rate variability (HRV) has been used to establish normative HRV values. This study aims to investigate whether HRV metrics can capture changes in HRV from external stimuli, and whether these metrics remain effective under various recording length. Participants completed varying stimulating activities including viewing images, arithmetic tasks, and memory recall of viewed images. SDNN, RMSSD, pNN50, SD2, SD1/SD2, and DFA were extracted from the data. Comparing arithmetic calculation and the first minute of memory recall, SDNN, pNN50, SD2, and SD1/SD2 had significant HRV differences; this suggests that these metrics can distinguish the inherently different stimuli participants were exposed to. However, comparing first minute of viewing with that of the second, SDNN, pNN50, and SD2, presented some significant HRV differences during two inherently similar stimuli. Comparing the first 60-120 s during viewing, SDNN, pNN50, and SD2 also presented significant differences. Our results suggest that SDNN, pNN50, and SD2 may not be robust in evaluating UST HRVs in replacement of the standard short-term HRV. It may be beneficial to analyze multiple HRV metrics, particularly SD1/SD2, to achieve a more holistic understanding of the underlying physiology.

Heart rate variability and cardiovascular risk factors in patients with rheumatoid arthritis: A longitudinal study.

It is established that the risk of cardiovascular disease (CVD) is increased in patients with Rheumatoid Arthritis (RA). Heart rate variability (HRV) is a method for evaluating the activity in the cardiac autonomic nervous system. Our aim was to assess the longitudinal development of HRV in patients with RA and compare with healthy controls. Furthermore, we wanted to investigate associations between HRV, inflammatory disease activity and cardiovascular complications in patients with RA over time. HRV was assessed with frequency-domain analysis at baseline and after five years in 50 patients with early RA, all being younger than 60years. HRV indices were age-adjusted based on the estimated age-dependency in 100 age and sex matched healthy controls. Additionally, clinical data including serological markers, disease activity, and blood pressure were collected from the patients. Eleven years after inclusion CVD was assessed. At baseline, patients with RA presented with lower HRV compared to controls during deep breathing (6 breaths/min), paced normal breathing (12 breaths/min) and after passive tilt to the upright position. No significant change in HRV was observed at the five-year follow-up. A significant negative correlation was found between HRV parameters and systolic blood pressure (SBP) at baseline. A significant positive correlation was found between heart rate and inflammatory markers at baseline but not after five years. Nine patients had developed CVD after 11years, but no significant association was found with baseline HRV data. This study showed that patients with RA have autonomic imbalance both at an early stage of the disease and after five years, despite anti-rheumatic medication, but no correlation between HRV and inflammation markers were observed. Reduced HRV was also significantly negatively correlated with increased SBP. Hypertension is a common finding in patients with RA. Thus, significant decline of HRV could be a useful early marker for development of hypertension in patients with RA.