Frequency Domain Indices Research Articles

Impact of exhaustive exercise on autonomic nervous system activity: insights from HRV analysis.

Exhaustive exercise is a common training method in sports, but its impact on the autonomic nervous system of the human body remains unclear. Understanding the effects of exhaustive exercise on the body and its connection with the autonomic nervous system and central nervous system is crucial for guiding healthy training methods. Twenty-three participants were selected, and exhaustive exercise intervention was performed using the Bruce Protocol. By measuring heart rate variability (HRV), the effects of exhaustive exercise on the autonomic nervous system function were analyzed. After exhaustive exercise, time-domain indices SDNN, RMSSD, and PNN50 all significantly decreased, with changes reaching significant levels (p < 0.01). Among them, the decrease in pNN50 was particularly pronounced, with a change rate of -94.55%. Frequency-domain indices VLF, LF, and HF also showed significant decreases (p < 0.01), but the ratio of LF to HF showed an upward trend (p < 0.01), with LF showing a greater decrease. Nonlinear indices SD1 and SD2 showed extremely significant decreases (p < 0.01), and the SD2/SD1 ratio showed a significant increase (p < 0.01), indicating significant changes in HRV nonlinear characteristics after exercise. Exhaustive exercise leads to a decrease in autonomic nervous system activity and an increase in sympathetic nervous system activity. These findings underscore the profound impact of exhaustive exercise on the autonomic nervous system, with implications for understanding the physiological responses to intense physical exertion. Further research is warranted to explore the long-term effects of exhaustive exercise on autonomic regulation and its potential implications for training methodologies and athlete health.

Linear classification of healthy people and patients with valvular heart diseases based on heart rate variability indices derived from electrocardiograms

Abstract Heart rate variability (HRV) is an important marker in various cardiovascular and non-cardiovascular conditions. This study aimed to evaluate the effectiveness of three linear models (Logistic Regression, Ridge Regression, Support Vector Machine) in distinguishing between healthy individuals and those with valvular heart diseases (VHD) using time domain and frequency domain HRV indices derived from electrocardiographic (ECG) signals. We analyzed 59 recordings taken from two public datasets containing electrocardiographic, seismocardiographic, and gyrocardiographic signals from “Mechanocardiograms with ECG reference” and “An Open-access Database for the Evaluation of Cardio-mechanical Signals from Patients with Valvular Heart Diseases” that contain 29 and 30 recordings, respectively. HRV analysis included time and frequency domain indices and the linear models were evaluated using 5-fold stratified cross-validation. The highest sensitivity, PPV, accuracy and F1 score were observed for Logistic Regression (0.8810, 0.8819, 0.8814, 0.8812), followed by Ridge Regression (0.8805, 0.8858, 0.8814, 0.8808), and the lowest were observed for linear SVM (0.8310, 0.8318, 0.8305, 0.8305). The results showed that it is possible to distinguish healthy volunteers and patients with linear classifiers and time domain and frequency domain HRV indices obtained from ECG signals with decent performance.

The effects of Baduanjin exercise on the psychological condition and heart rate variability of sports-disadvantaged college students: A randomised trial

ObjectiveTo investigate the effects of a 16-week Baduanjin exercise programme on the psychological status and heart rate variability (HRV) of college students in a sports-disadvantaged group, offering a theoretical basis for the potential of Baduanjin exercise to improve mental health.Trial DesignThis prospective study enrolled 93 college students from Wuyi University, exempt from the National Standards for Students’ Physical Health due to illness or disability. The participants were divided into a control group (n = 47) and an experimental group (n = 46). Over 16 weeks, the experimental group engaged in the Baduanjin exercise, whereas the control group did not participate in regular physical training.MethodsWe assessed the Symptom Checklist-90-Revised (SCL-90-R, the primary outcome) scores and HRV (time domain and frequency domain indices, the secondary outcomes) of all participants both before and after the 16-week programme.Results(1) Post-16 weeks of Baduanjin exercise, a statistically significant difference was observed in the SCL-90-R scores between the control and experimental groups (P < 0.01, P < 0.05). Notably, the scores for interpersonal sensitivity, depression, anxiety, psychoticism, and other factors (predominantly relating to sleep and diet) were significantly lower in the experimental group (t = 4.234, 2.616, 3.450, 2.226, 3.980, P < 0.01, P < 0.05). (2) Following the exercise regimen, the experimental group showed a substantial decrease in heart rate, low-frequency (LF) power, and the LF/high-frequency ratio (LF/HF ratio), and a significant increase in HF compared with the control group (t = 2.358, 4.528, − 2.595, P < 0.05 P < 0.01).ConclusionSixteen weeks of Baduanjin exercise may substantially enhance HRV, potentially aiding in balancing sympathetic–vagal nerve activity and thus contributing to the regulation of mental health.

Heart rate variability and insomnia in depressed patients with breast cancer

ObjectivesDepression is associated with unhealthy autonomic regulation. However, whether patients with breast cancer (BC) with different degrees of depression can be identified from linear and non-linear dynamics in the autonomic...

Effects of adipose tissues on the relationship between type 2 diabetes mellitus and reduced heart rate variability: mediation analysis.

Type 2 diabetes mellitus (T2DM) is associated with decreased heart rate variability (HRV) with an unclear intermediate mechanism. This study aimed to conduct mediation analysis to explore the impact of various adipose tissues on the relationship between T2DM and HRV. A total of 380 participants were enrolled for analysis, including 249 patients with T2DM and 131 non-diabetic controls. The thicknesses of four adipose tissues (subcutaneous, extraperitoneal, intraperitoneal, and epicardial) were measured by abdominal ultrasound or echocardiography respectively. HRV was assessed by 24-hour Holter for monitoring both frequency domain indices (LF, HF, and LF/HF) and time domain indices (SDNN, SDANN, SDNN index, rMSSD and pNN50). Mediation analysis was used toexamine whether adipose tissues mediated the relationship between T2DM and each index of HRV. Then, a latent variable - HRV burden - was constructed by structural equation model with selected HRV indices to comprehensively assess the whole HRV. Compared to non-diabetic controls, patients with T2DM exhibited a significant reduction in indices of HRV, and a remarkable increase in the thicknesses of extraperitoneal, intraperitoneal, and epicardial adipose tissues. Mediation analysis found significant indirect effects of T2DM on six indices of HRV, including HF, SDNN, SDANN, SDNN index, rMSSD, and pNN50, which was mediated by epicardial adipose tissue rather than other adipose tissues, with the mediation proportions of 64.21%, 16.38%, 68.33%, 24.34%, 24.10% and 30.51%, respectively. Additionally, epicardial adipose tissue partially mediated the relationship between T2DM and reduced HRV burden (24.26%), which composed by SDNN, SDNN index, rMSSD, and pNN50. Epicardial adipose tissue partially mediated the relationship between T2DM and reduced HRV, which reinforces the value of targeting heart-specific visceral fat to prevent cardiac autonomic neuropathy in diabetes.

Ultra-short heart rate variability reliability for cardiac autonomic tone assessment in severe traumatic brain injury

This study compares heart rate variability (HRV) indices across different time epochs (5 minutes, 1 minute, and 30 seconds) to evaluate the reliability of ultra-short recordings for assessing cardiac autonomic tone 1 year after a severe traumatic brain injury (TBI). Electrocardiogram recordings were obtained from 48 patients 1 year after a severe TBI. Pearson correlation analysis was performed to evaluate the association between ultra-short HRV indices (1 minute and 30 seconds) and the standard 5-minute recordings. Additionally, ANOVA was used to compare the differences in mean HRV indices across the different epochs. The correlation analysis supports that time-domain indices present higher correlation coefficients (r = 0.63 to 0.99, p &lt; 0.05) when compared with frequency-domain indices (r = 0.51 to 0.97, p &lt; 0.05). The reduction in recording time increases the percentage variation of all indices. The root mean square of the successive differences of RR intervals (rMSSD) shows higher Pearson coefficient values and lower percentage variation at the 1-minute and 30-second epochs compared with other HRV indices. Ultra-short HRV indices are reliable for assessing cardiac autonomic tone in chronic patients who survived severe TBI. rMSSD was the most reliable HRV index for ultra-short recordings. The value of ultra-short HRV for cardiovascular prognosis after severe TBI remains to be determined in future studies.

Frequency-Domain Features and Low-Frequency Synchronization of Photoplethysmographic Waveform Variability and Heart Rate Variability with Increasing Severity of Cardiovascular Diseases.

Objective-Heart rate variability (HRV) and photoplethysmographic waveform variability (PPGV) are available approaches for assessing the state of cardiovascular autonomic regulation. The goal of our study was to compare the frequency-domain features and low-frequency (LF) synchronization of the PPGV and HRV with increasing severity of cardiovascular diseases. Methods-Our study included 998 electrocardiogram (ECG) and finger photoplethysmogram (PPG) recordings from subjects, classified into five categories: 53 recordings from healthy subjects, aged 28.1 ± 6.2 years, 536 recordings from patients with hypertension (HTN), 49.0 ± 8.8 years old, 185 recordings from individuals with stable coronary artery disease (CAD) (63.9 ± 9.3 years old), 104 recordings from patients with myocardial infarction (MI) that occurred three months prior to the recordings (PMI) (65.1 ± 11.0 years old), and 120 recordings from study subjects with acute myocardial infarction (AMI) (64.7 ± 11.5 years old). Spectral analyses of the HRV and PPGV were carried out, along with an assessment of the synchronization strength between LF oscillations of the HRV and of PPGV (synchronization index). Results-Changes in all frequency-domain indices and the synchronization index were observed along the following gradient: healthy subjects → patients with HTN → patients with CAD → patients with PMI → patients with AMI. Similar frequency-domain indices of the PPGV and HRV show little relationship with each other. Conclusions-The frequency-domain indices of the PPGV are highly sensitive to the development of any cardiovascular disease and, therefore, are superior to the HRV indices in this regard. The S index is an independent parameter from the frequency-domain indices.

Reduced heart rate variability is associated with altered clinical laboratory profile in people living with HIV

BackgroundWe compared heart rate variability (HRV) indices between people living with HIV (PLWH) and HIV-negative individuals to ascertain the independent association between HIV infection and reduced HRV, and further investigated whether distinct clinical laboratory profiles exist between PLWH with and without reduced HRV. MethodsThis cross-sectional analysis included 304 PLWH and 147 HIV-negative individuals with comparable age and sex. Thirty-two routine clinical laboratory indices (including hematology and biochemistry) closest to the survey were extracted from the Electronic Medical Record System. HRV indices were divided into two categories: low (lowest quartile, Q1) and moderate-to-high (combined, Q2‒Q4). ResultsThe time domain indices, ln(SDNN), ln(RMSSD), and ln(PNN50), as well as the frequency domain indices, ln(HF), ln(LF), and ln(VLF), were all significantly reduced in PLWH versus HIV-negative individuals (all p < 0.05). These associations remained for ln(SDNN), ln(PNN50), ln(HF) and ln(LF) even after adjusting for potential confounders in multivariable models. PLWH with low HRV indices exhibited distinct clinical laboratory profiles that were characterized by an elevation in fasting plasma glucose, white blood cell count, neutrophil count, neutrophil%, and a reduction in albumin, total protein, urine creatinine, lymphocyte%, red blood cell count (RBC) and nadir CD4 count. The final stepwise logistic regression models for low SDNN included older age, decreased total cholesterol levels, elevated neutrophil count, and the use of antidiabetic medications, whereas the final model for low LF included older age, reduced RBC and the use of antidiabetic medications. ConclusionPLWH exhibit impaired parasympathetic activity, as evidenced by reduced SDNN, PNN50, LF and HF. Furthermore, PLWH who have reduced HRV indices exhibits distinct clinical laboratory profiles that are related to systematic inflammatory response and diabetes.

Heart Rate Variability in Military Pilots During Flight: A Scoping Review.

Piloting an aircraft is a complex multitasking activity that involves managing information in a nonautomatic way and generates a high workload (psychological, cognitive, and physical) for the pilot. The excess of these demands can result in decreased performance and may impair flight safety. Heart rate variability (HRV) has been used in recent studies as a method to investigate operator's workload in complex environments. This measure can assess the stress and recovery ability of the autonomic nervous system. However, a better understanding of flight influence on the pilot's autonomic modulation is necessary. Therefore, this scoping review aims to systematically map the studies related to changes in the autonomic modulation in military pilots during flight, in order to characterize their workload at different times and flight profiles. A literature search was conducted using MEDLINE (by PubMed), SCOPUS, and LILACS databases. Recent records (2002-2022) that analyzed HRV in military pilots during flight were included. Meanwhile, studies in which piloting activity was not performed were excluded. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline extension for Scoping Reviews and the Updated Methodological Guidance for the Conduct of Scoping Reviews. A total of 298 records were obtained, of which 19 were included in the scoping review. The studies analyzed flights performed in high- and low-performance aircrafts, helicopters, and flight simulators, using time domain, frequency domain, and nonlinear HRV indices. Real and simulated flights produced significant autonomic changes. Some flights elicited autonomic nervous system responses that persisted up to 5 h after landing. During real flight, the most sensitive indices for identifying variations in pilot workload were root mean square of successive differences between normal heartbeats, standard deviation of interbeat interval of normal sinus beat (SDNN), ratio of low-frequency to high-frequency power, and Poincaré plot standard deviation perpendicular to the line of identity (SD1), whereas the interbeat interval (RR), SDNN, SD1, and Poincaré plot standard deviation along the line of identity (SD2) were the most sensitive indices when comparing segments of simulated flight with different levels of difficulty. This scoping review provided insight into the influence of flight on autonomic modulation in military pilots. Some key themes were highlighted: Increased sympathetic activity during flight, sensibility of different domains of HRV to flight demands, and autonomic changes during recovery time. Future research efforts may allow us to enhance the understanding of pilot's workload limits and to elucidate the optimal postflight recovery time.

Neuroinflammation in the medullary visceral zone exert a powerful impaction on the systemic inflammation in sepsis through cholinergic anti-inflammatory pathway

To investigate whether sepsis-induced neuroinflammation of medulla visceral zone (MVZ) predominates the systemic inflammation through cholinergic anti-inflammatory pathway (CAP), and to explore the effect of central anti-inflammation on systemic inflammation. 112 adult Sprague–Dawley male rats were randomly divided into sepsis experimental group (n = 56) and neuroinflammation experimental group (n = 56). The two experimental groups were individually randomly divided into control group (n = 8), model group (n = 16), central anti-inflammatory group (n = 16) and vagus transection group (n = 16). Rats in two control groups were administered with saline at the dose of 6 mL/kg intraperitoneally or with 25 μL artificial cerebrospinal fluid injected into forth ventricle once a day for 3 days. Rats in two model groups were administered with Lipopolysaccharide (LPS) at the dose of 6 mg/kg intraperitoneally or with 25 μg/25 μL LPS injected into forth ventricle once a day for 3 days. Rats in two central anti-inflammatory groups were fed with 10 mg/mL minocycline sucrose solution as the only water source for 4 days prior to be treated as the model groups of their own, and feeding style was continued until the end of the experiment. Rats in the two vagus transection groups were undergone right vagotomy and 7 days of adaptive feeding prior to be treated as the same as those in the central anti-inflammatory group of their own. The Murine Sepsis Score (MSS), mortality rate and heat rate variability (HRV) were recorded during the last 3 days of intervention. Then the rats were sacrificed and blood samples were collected for ELISA analysis to detect the serum level of inflammatory cytokines such as TNF-α, IL-6, and IL-10. The expression of TNF-α and IL-6 in medulla oblongata were analyzed by Western blot. The correlation and regression analysis among the expression levels of cytokines in medulla oblongata, HRV indexes and serum inflammatory cytokines were performed. The mortality rate and MSS of the sepsis model group and the MVZ’s neuroinflammation model group were significantly higher than those of their own control group, and the central anti-inflammation reduced the mortality rate and MSS scores of the two model groups, while the right vagotomy abolished the effect of central anti-inflammatory. In the sepsis model group and the MVZ’s neuroinflammation model group, the levels of TNF-α, IL-6, and other cytokines in serum and MVZ were significantly increased, and HRV indexes (SDNN, RMSSD, LF, HF, LF/HF) were significantly decreased (P = 0.000). Central anti-inflammatory treatment reversed the above changes. However, right vagotomy abolished the central anti-inflammatory effect. Correlation and regression analysis showed that there was a significant linear correlation among the expression of inflammatory factors in MVZ, the indexes of HRV and the levels of serum cytokines. Our study shows that sepsis-induced MVZ’s neuroinflammation exert a powerful influence on the systemic inflammation through CAP in sepsis. Central anti-inflammation effectively improves systemic inflammation through inhibiting MVZ’s neuroinflammation in sepsis. The time domain and frequency domain indexes of HRV can reflect the regulatory effect of CAP and the degree of inflammation of MVZ, which may be potentially used to monitor the condition and treatment effectiveness of sepsis patients.

Effects of Biofeedback Training on HRV, Mood State and Shooting Performance of Shooters

This study investigates the effects of biofeedback training on the HRV, emotional state, and shooting performance of athletes. Results indicate significant improvement in athletes' HRV frequency domain indices (p &lt; 0.05), reduced negative emotions like tension and anger (p &lt; 0.05), increased vitality and positivity, though changes in fatigue and self-emotional state weren't statistically significant (p &gt; 0.05). Shooting performance significantly improved post-training (p &lt; 0.01). This suggests that biofeedback training positively impacts autonomic nervous system function, emotional stability, and shooting skills. Biofeedback training significantly enhances shooting performance by improving HRV, optimizing emotional state, and strengthening emotional regulation abilities.

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.

Exploring the Impact of Campus Landscape Visual Elements Combination on Short-Term Stress Relief among College Students: A Case from China

Although the effect of campus landscape space on stress relief among college students has been confirmed, few existing studies have considered the impact on stress recovery from the perspective of factor combination, and the key visual elements and the most effective combination of visual elements to relieve stress are still unclear. This study attempts to conduct a natural experiment within Chinese campuses, measuring physiological indicators of stress such as heart rate (HR), frequency domain index of heart rate variability (LF/HF), skin conductance level (SCL), skin temperature (SKT), and respiratory rate (RESP) using physiological instruments. It explored the effects of visual elements and their combinations in campus landscape spaces on short-term stress relief among college students through semantic segmentation, multifactorial analysis of variance, and post hoc multiple comparison methods. Research results demonstrate that the presence of water elements in the field of vision can effectively improve the stress relief effects of landscape spaces. Reasonable combinations of natural landscape elements and artificial landscape elements in the design can also effectively promote stress relief among students. Building facade area and sky area, water area and sky area, and plant species and pavement area are three combinations of factors with the strongest interactive effects. “Natural water scenery” and “exquisite artificial” are two campus landscape design patterns most conducive to short-term stress relief.

Cardiac Autonomic and Endothelial Function in Acute Lymphoblastic Leukaemia Patients Immediately After Chemotherapy and at the Three-Month Follow-up.

Acute lymphoblastic leukemia (ALL) is a malignant uncontrolled overproduction of immature lymphoid cells in blood and bone marrow. The primary treatment of ALL is chemotherapy. Chemotherapy can have myriad systemic side effects, notably cardiovascular derangement. Autonomic derangement occurrence in cancer patients signifies cardiovascular risk in them and is a determinant of cardiovascular morbidity and mortality. Elevated soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1) levels implicated in the regulation of inflammation indicate endothelial dysfunction. High levels of high-sensitivity C-reactive protein (hsCRP) can be indicative of low-grade inflammation. Hence, in this study the cardiac autonomic function and endothelial and inflammatory biomarker levels in adult patients with ALLwere assessed immediately and three months after chemotherapy. In this longitudinal study, 30 ALL patients (23 males, seven females) aged between 18 to 50 years, who had completed chemotherapy regimens, and 30 age and gender-matched healthy participants (controls) were recruited. Cardiac autonomic function tests (short-term heart rate variability (HRV), 30:15 ratio, synaptic excitation and inhibition (E/I) ratio, diastolic blood pressure (DBP) response to isometric hand grip), endothelial markers (sVCAM-1 and sICAM-1), and inflammatory marker (hsCRP) were assessed immediately and at three months after chemotherapy. Magnitudes of time domain and frequency domain indices, conventional autonomic function test indices, and biomarkers were deranged in ALL patients immediately after chemotherapy. After three months, cardiac autonomic function parameters were found to improve in the form of increased root mean square of successive differences between normal heartbeats (RMSSD), standard deviation of the interbeat intervals of normal sinus beats (SDNN), total power, high-frequency (HF)nu, and decreased low-frequency(LF)nu & LF-HF ratio. Endothelial (sVCAM-1) and inflammatory markers (hsCRP) were lower in the patient group as compared to the controls immediately after chemotherapy. Three months after chemotherapy, the levels of endothelial and inflammatory markers did not show much change. In this study, we found ALL patients showed higher sympathetic drive, decreased parasympathetic modulation, and sympathovagal imbalance immediately after chemotherapy as compared to the controls, indicating cardiovascular risk. After three months, improvement in cardiovascular autonomic function was observed. ALL itself is a state of inflammation with elevated endothelial and inflammatory markers; thus, the decreased endothelial and inflammatory markers could be attributed to the immediate effect of chemotherapy.

The value of circadian heart rate variability for the estimation of obstructive sleep apnea severity in adult males.

Heart rate variability (HRV) is becoming more prevalent as a measurable parameter in wearable sleep-monitoring devices, which are simple and effective instruments for illness evaluation. Currently, most studies on investigating OSA severity and HRV have measured heart rates during wakefulness or sleep. Therefore, the objective of this study was to investigate the circadian rhythm of HRV in male patients with OSA and its value for the estimation of OSA severity using group-based trajectory modeling. Patients with complaints of snoring were enrolled from the Sleep Center of Shandong Qianfoshan Hospital. Patients were divided into 3 groups according to apnea hypopnea index (AHI inevents/h), as follows: (<15, 15≤AHI<30, and ≥30). HRV parameters were calculated using 24 h Holter monitoring, which included time-domain and frequency-domain indices. Circadian differences in the standard deviation of normal to normal (SDNN) were evaluated for OSA severity using analysis of variance, trajectory analysis, and multinomial logistic regression. A total of 228 patients were enrolled, 47 with mild OSA, 48 moderate, and 133 severe.Patients with severe OSA exhibited reduced triangular index and higher very low frequency than those in the other groups. Circadian HRV showed that nocturnal SDNN was considerably higher than daytime SDNN in patients with severe OSA. The difference among the OSA groups was significant at 23, 24, 2, and 3 o'clock sharp between the severe and moderate OSA groups (all P<0.05). The heterogeneity of circadian HRV trajectories in OSA was strongly associated with OSA severity, including sleep structure and hypoxia-related parameters. Among the low-to-low, low-to-high, high-to-low, and high-to-high groups, OSA severity in the low-to-high group was the most severe, especially compared with the low-to-low and high-to-low SDNN groups, respectively. Circadian HRV in patients with OSA emerged as low daytime and high nocturnal in SDNN, particularly in men with severe OSA. The heterogeneity of circadian HRV revealed that trajectories with low daytime and significantly high nighttime were more strongly associated with severe OSA. Thus, circadian HRV trajectories may be useful to identify the severity of OSA.

Data Analysis of Heart Rate Variability and Arrhythmia in Patients with Paroxysmal Atrial Fibrillation.

Atrial fibrillation (AF) is the most common type of arrhythmia. Heart rate variability (HRV) may be associated with AF risk. The aim of this study was to test HRV indices and arrhythmias as predictors of paroxysmal AF based on 24-hour dynamic electrocardiogram recordings of patients. A total of 199 patients with paroxysmal AF (AF group) and 204 elderly volunteers over 60 years old (Control group) who underwent a 24-hour dynamic electrocardiogram from August 2022 to March 2023 were included. Time-domain indices, frequency-domain indices, and arrhythmia data of the two groups were classified and measured. Binary logistic regression analysis was performed on variables with significant differences to identify independent risk factors. A nomogram prediction model was established, and the sum of individual scores of each variable was calculated. Gender, age, body mass index and low-density lipoprotein (LDL) did not differ significantly between AF and Control groups (p > 0.05), whereas significant group differences were found for smoking, hypertension, diabetes, and high-density lipoprotein (HDL) (p < 0.05). The standard deviation of all normal to normal (NN) R-R intervals (SDNN), standard deviation of 5-minute average NN intervals (SDANN), root mean square of successive NN interval differences (rMSSD), 50 ms from the preceding interval (pNN50), low-frequency/high-frequency (LF/HF), LF, premature atrial contractions (PACs), atrial tachycardia (AT), T-wave index, and ST-segment index differed significantly between the two groups. Logistic regression analysis identified rMSSD, PACs, and AT as independent predictors of AF. For each unit increase in rMSSD and PACs, the odds of developing AF increased by 1.0357 and 1.0005 times, respectively. For each unit increase in AT, the odds of developing AF decreased by 0.9976 times. The total score of the nomogram prediction model ranged from 0 to 110. The autonomic nervous system (ANS) plays a pivotal role in the occurrence and development of AF. The individualized nomogram prediction model of AF occurrence contributes to the early identification of high-risk patients with AF.

Association between heart rate variability and neutrophil-lymphocyte ratio in individuals with prehypertension – A cross-sectional study

Background: High blood pressure, commonly termed hypertension, is becoming more common in both developing and industrialized nations, making it a worldwide health concern. An increase in blood pressure is broadly categorized into prehypertension and hypertension based on JNC VIII criteria. Prehypertension is a state in between normal blood pressure and high blood pressure, and it is linked with injury to target organs and subclinical atherosclerosis an easy and non-invasive way to look into autonomic dysfunction in those who are pre-hypertensive is to measure heart rate variability (HRV). Neutrophil-to-lymphocyte ratio (NLR) is a cheap, simple, and novel hematological parameter of oxidative stress and pro-inflammatory marker and has recently emerged as a useful indicator to predict cardiovascular risk and adverse outcomes in patients with hypertension. Aims and Objectives: The aim of the study is to assess the correlation between cardiovascular autonomic function using HRV and NLR in pre-hypertensive individuals and to find out if NLR can be used as a marker to detect autonomic dysfunction. Materials and Methods: HRV is recorded in a supine position with eyes closed in the study population. About 2 mL of venous blood was collected from the individuals to measure NLR using an automated hematology analyzer. Results: The mean values of time domain indices showed significant reduction and frequency domain indices low frequency (LF) values were significantly higher and high frequency (HF) values were significantly lower in pre-hypertensive. The mean NLR was significantly higher in pre-hypertensive individuals. Time domain indices showed a negative correlation with NLR. HF values were negatively correlated and LF values were positively correlated with NLR. Conclusion: NLR was increased in pre-hypertensive individuals which suggest that people in pre-hypertensive state are also at risk of developing cardiovascular and cerebrovascular complications. This study showed a positive association between NLR and sympathetic activity and a negative association between NLR and parasympathetic activity. This concludes that NLR could be used as a marker to assess autonomic dysfunction in them.

Para table tennis improves psychological/mental and cardiovascular health in individuals with spinal cord injury.

Although rehabilitation exercise is known to be beneficial for cardiovascular and mental health, it remains a daunting challenge for patients with spinal cord injury (SCI) who rely on wheelchairs for mobility. This study aimed to examine the effectiveness of a 4-week para table tennis program in enhancing self-efficacy and health outcomes in adults with SCI. A total of 39 SCI patients were included and divided into the experimental group (n = 18, a 4-week para table tennis training program) and the control group (n = 21). Frequency domain indices of heart rate variability (HRV) were used to evaluate the function of the autonomic nervous system. Following para table tennis training, there was a significant reduction in the physical stress index (PSI, P < 0.001), accompanied by shifts in autonomic regulation of vagal dominance. Additionally, the para table tennis training led to significant improvements in vessel state, differential pulse wave index, atrial elasticity, eccentric constriction power, remaining blood volume, and self-efficacy (all P < 0.05). Para table tennis training results in favorable changes in sympathetic tone, enhanced self-efficacy, improved cardiovascular well-being, and an overall positive transformation in HRV.

Postural balance disorders in sarcopenia based on surface electromyography

BackgroundSarcopenia is an intrinsic factor that leads to balance disorders and falls in older adults. However, the characterization of sarcopenia-related postural balance deficits remains unclear. AimsThis study aimed to explore the balance performance and postural control strategy in older adults with sarcopenia during static stance tasks using force platforms and surface electromyography. MethodsOlder adults with right-sided dominance were recruited, including 27 adults with sarcopenia and 27 healthy counterparts. Postural sway was measured with eyes open/closed on rigid/compliant surfaces. The time- and frequency-domain indexes of bilateral lower extremity muscle activity were simultaneously recorded. ResultsThe postural sway and activity of multiple lower extremity muscles in the sarcopenia group were increased (P < 0.05). The amplitude contribution ratio of the right tibialis anterior muscle (larger in sarcopenia), co-contraction ratio of right ankle dorsiflexion (smaller in sarcopenia), and mean power frequency and median frequency of the left gluteus maximus muscle (smaller in sarcopenia) had main effects of grouping (P < 0.001, η2p = 0.06–0.10). All of them had discrimination for sarcopenia (area under the curve = 0.639–0.657, P < 0.001) and were correlated with balance function measurement in sarcopenia (|rs| = 0.22–0.44, P < 0.05). ConclusionThe results of this study suggest that older adults with sarcopenia have decreased balance function and increased cost of electrophysiology. They were found to prefer the postural strategy of dominant ankle dorsiflexion and demonstrated overactivity of the dominant tibialis anterior muscles and fatigue vulnerability of the nondominant gluteus maximus. Improvements in these postural features may have balance benefits.

Neuroimmune modulation mediated by IL-6: A potential target for the treatment of ischemia-induced ventricular arrhythmias

BackgroundNeural remodeling in the left stellate ganglion (LSG), as mediated by neuroimmune reactions, promotes cardiac sympathetic nerve activity (SNA) and thus increases the incidence of ventricular arrhythmias (VAs). Interleukin-6 (IL-6) is an important factor of the neuroimmune interaction. ObjectiveThe present study explored the effects of IL-6 on LSG hyperactivity and the incidence of VAs. MethodsEighteen beagles were randomly allocated to a control group (saline with myocardial infarction [MI], n = 6), adeno-associated virus (AAV) group (AAV with MI, n = 6), and IL-6 group (overexpression of IL-6 via AAV vector with MI, n = 6). Ambulatory electrocardiography was performed before and 30 days after AAV microinjection into the LSG. LSG function and ventricular electrophysiology were assessed at 31 days after surgery, and a canine MI model was established. Samples of the LSG were collected for immunofluorescence staining and molecular biological evaluation. Blood samples and 24-hour Holter data were obtained from 24 patients with acute MI on the day after they underwent percutaneous coronary intervention to assess the correlation between IL-6 levels and SNA. ResultsIL-6 overexpression increased cardiac SNA and worsened postinfarction VAs. Furthermore, sustained IL-6 overexpression enhanced LSG function, promoted expression of nerve growth factor, c-fos, and fos B in the LSG, and activated the signal transducer and activator of transcription 3/regulator of G protein signalling 4 signaling pathway. Clinical sample analysis revealed a correlation between serum IL-6 levels and heart rate variability frequency domain index as well as T-wave alternans. ConclusionIL-6 levels are correlated with cardiac SNA. Chronic overexpression of IL-6 mediates LSG neural remodeling through the signal transducer and activator of transcription 3/regulator of G protein signalling 4 signaling pathway, elevating the risk of VA after MI.