Fibromyalgia unplugged: Heart rate variability as a window to autonomic regulation

Emerging evidence suggests a link between muscle health and the autonomic nervous system, but research is scarce. This study examines the connection between long-term heart rate variability (HRV) measured autonomic function and sarcopenia in the elderly, focusing on muscle mass and strength. This retrospective cross-sectional study comprised 132 elderly hospitalized patients. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People (EWGSOP2) criteria, involving reduced muscle mass and strength. HRV was assessed using standard deviation of NN intervals (SDNN), with values below 100 milliseconds indicating reduced HRV. Multivariate logistic regression and Pearson's correlation analyses were conducted to explore the associations between sarcopenia, muscle metrics, and HRV parameters. Among elderly hospitalized patients, 45.45% had reduced HRV, with sarcopenia patients showing a fivefold higher risk (OR: 5.042; p = 0.034). Grip strength and SARC-CalF scores were independent factors associated with reduced HRV. Moderate correlations were noted between grip strength and HRV indices, particularly with SDNN (r = 0.393, p = 0.001) and the triangular index (r = 0.385, p < 0.001), while a weaker correlation was found with very low frequency power (VLF) (r = 0.283, p = 0.006). No significant correlations were identified between HRV and muscle mass. Regression analyses revealed significant independent associations between HRV parameters and the decline in muscle strength and the onset of sarcopenia. Reduced HRV is closely linked to sarcopenia and diminished muscle strength in the elderly, with the triangular index and SDNN as key indicators, highlighting HRV's potential in muscle health assessment.

Objective To investigate the characteristics of heart rate variability (HRV) of ambulatory electrocardiogram in patients with acute stroke, and evaluate the predictive value of HRV in stroke prognosis. Methods Eighty-three patients acute stroke (study group) and 83 cases of healthy subjects (control group) from October 2016 to October 2017 in Dalian Municipal Central Hospital Affiliated of Dalian Medical University were selected. The 24 h ambulatory electrocardiogram was performed to determine HRV in 2 groups, including standard deviation of NN intervals (SDNN), standard deviation of the 5 min mean cycle lengths (SDANN), root-mean-square successive difference (RMSSD) and percentage value of NN50 count (PNN50). Results The SDNN, SDANN, RMSSD and PNN50 in study group were significantly lower than those in control group: (80.83 ± 10.52) ms vs. (148.11 ± 22.59) ms, (79.98 ± 8.89) ms vs. (129.35 ± 5.34) ms, (19.28 ± 4.25) ms vs. (39.57 ± 2.38) ms and (5.91 ± 2.12)% vs. (19.35 ± 12.15)%, and there were statistical differences (P 0.05). The SDNN, SDANN, RMSSD and PNN50 in right stroke (43 cases) were significantly lower than those in left stroke (40 cases):(75.18 ± 2.32) ms vs. (88.12 ± 3.58) ms, (73.36 ± 2.18) ms vs. (85.69 ± 7.29) ms, (17.57 ± 1.67) ms vs. (20.58 ± 4.23) ms and (4.39 ± 1.57)% vs. (8.61 ± 1.12)%, and there were statistical differences (P<0.05). Patients were followed up for 1 year, 24 died and 59 survived. The SDNN, SDANN, RMSSD and PNN50 in dead patients were significantly lower than those in survived patients: (92.35 ± 4.58) ms vs. (154.37 ± 4.65) ms, (76.23 ± 4.03) ms vs. (143.95 ± 4.34) ms, (7.43 ± 2.12) ms vs. (31.65 ± 1.52) ms and (2.35 ± 0.46)% vs. (11.65 ± 0.48)%, and there were statistical differences (P<0.05). Conclusions The autonomic nervous function of patients with acute stroke is seriously unbalanced, with increased sympathetic excitability and decreased vagus excitability. The decrease of HRV can easily induce cardiac events and seriously affect the prognosis. Key words: Stroke; Prognosis; Heart rate viability; Autonomic nervous function

PurposeDue to recent advances in diagnosis and treatment, the number of adults with congenital heart disease (ACHD) has substantially increased. This achievement is mitigated by rhythm disorders. Here, we sought to determine alterations in heart rate variability (HRV) and their prognostic value in ACHD.MethodsNinety seven ACHD patients (39.2 ± 14.1 years, 51.5% female) and 19 controls (39.7 ± 15.0 years, 47.4% female) underwent 24-h Holter monitoring.ResultsAs compared to controls, ACHD patients offered a significantly higher burden of premature ventricular contractions (p = 0.02) and decreased HRV indices (natural logarithmic transformation of very low frequency (lnVLF): 7.46 ± 0.76 ms2 vs. 7.91 ± 0.92ms2, p = 0.03; natural logarithmic transformation of low frequency (lnLF): 6.39 ± 0.95ms2 vs. 7.01 ± 1.07ms2, p = 0.01; natural logarithmic transformation of the ratio of low to high frequency spectra (lnLF/HF): 0.81 ± 0.74 vs. 1.17 ± 0.51, p = 0.04). No differences in HRV measures were observed across ACHD lesion groups. NT-proBNP levels were significantly related to both time and frequency domain indices (natural logarithmic transformation of the standard deviation of NN intervals (lnSDNN): Spearman´s rho = -0.32, p = 0.001; natural logarithmic transformation of the standard deviation of the average NN intervals for each 5-min segment of a 24-h Holter monitoring (lnSDANN): Spearman´s rho: -0.33, p = 0.001; natural logarithmic transformation of the total power (lnTP): Spearman´s rho: -0.25, p = 0.01; lnVLF: Spearman´s rho: -0.33, p = 0.001; lnLF: Spearman´s rho: -0.35, p < 0.001; lnLF/HF: Spearman´s rho: -0.34, p = 0.001).After a mean follow-up of 3.9 ± 0.7 years, 8 patients died and 3 patients survived sudden cardiac death (SCD). Several HRV parameters were significantly higher in event-free ACHD patients than in those who died or survived SCD (natural logarithmic transformation of the average of the standard deviations of NN intervals for each 5-min segment of a 24-h Holter monitoring (lnASDNN): p = 0.04; lnPNN30: p = 0.04; lnVFL: p = 0.03; lnLF: p < 0.01). On univariate Cox regression analysis, the time domain indices lnSDNN, lnASDNN and lnPNN30, as well as the frequency domain parameters lnTP, lnVLF and lnLF were associated with death and survived cardiac arrest.ConclusionACHD is accompanied by HRV impairment that carries prognostic implications on ACHD mortality and survived SCD.

Transient global amnesia (TGA) often involves precipitating events associated with changes in autonomic nervous system (ANS), and heart rate variability (HRV) reflects the ANS state. This study aimed to investigate HRV changes after TGA. A retrospective analysis of HRV included patients diagnosed with TGA between January 2015 and May 2020. The time and frequency domains of HRV were compared among three groups: early (< 1 week after TGA, n = 19), late (1–4 weeks after TGA, n = 38), and healthy control (HC, n = 19). The Pearson’s correlation between time and time-domain HRV was also examined. The standard deviation of NN intervals (SDNN) (early, 47.2; late, 35.5; HC, 41.5; p = 0.033) and root mean square of successive RR interval differences (RMSSD) (early, 38.5; late, 21.3; HC, 31.0; p = 0.006) differed significantly among the three groups. Post-hoc analysis showed statistically significant differences only in the early and late groups in both SDNN (p = 0.032) and RMSSD (p = 0.006) values. However, the frequency domain with total power, low-frequency and high-frequency powers, and low-frequency/high-frequency ratio did not differ. SDNN (Pearson correlation coefficient =− 0.396, p = 0.002) and RMSSD (Pearson correlation coefficient =− 0.406, p = 0.002) were negatively correlated with time after TGA. Changes in HRV occurred over time after the onset of TGA, with the pattern showing an increase in the first week and then a decrease within 4 weeks.

Does empagliflozin modulate the autonomic nervous system among individuals with type 2 diabetes and coronary artery disease? The EMPA-HEART CardioLink-6 Holter analysis

Previous studies have demonstrated that reduced heart rate variability (HRV) and hypovitaminosis D are associated with cardiovascular disease (CVD). However, few reports have investigated the effects of vitamin D on HRV. This cross-sectional study analyzed serum 25-hydroxyvitamin D (25(OH)D) and HRV indices using 5-min R-R interval recordings with an automatic three-channel electrocardiography in healthy subjects (103 males and 73 females). Standard deviation of N-N interval (SDNN), square root of mean squared differences of successive N-N intervals (RMSSD), total power (TP), very low frequency (VLF), low frequency (LF), and high frequency (HF) were reported. The mean age of subjects was 55.3 ± 11.3 years and the mean 25(OH)D level was 21.2 ± 9.9 ng/mL. In a multiple linear regression model, 25(OH)D was positively correlated with SDNN (β = 0.240, p < 0.002), and LF (β = 0.144, p = 0.044). Vitamin D deficiency (25(OH)D < 15 ng/mL) was associated with decreased SDNN (<30 m/s) (OR, 3.07; 95% confidence interval (CI), 1.32–7.14; p = 0.014) after adjusting for covariates. We found that lower 25(OH)D levels were associated with lower HRV, suggesting a possible explanation for the higher risk of CVD in populations with hypovitaminosis D.

HRV is an indicator of autonomic function, inflammation, and autonomic dysfunction. Evidence suggests an inverse relationship between HRV (SDNN standard deviation of NN intervals) and inflammation, with multiple reports indicating COVID-19 vaccination (vac) related to ANS dysfunction. The vac effect is not fully known, some reporting it incites inflammation while others found the effects were temporary. Given the conflicting results, additional research is needed. PURPOSE: Identify differences in HRV, coherence (a state of physiological function shifted toward parasym. activity), and stress index scores between students enrolled in a health/wellness course who did (n = 44) and did not (n = 23) receive COVID-19 vac. Timing of the vac related to data collected was not determined nor were non-vac subjects asked of exposure or infection with COVID. METHODS: Biometric data (ht, wt, body comp, mile walk VO2 (ml/kg/min), HRV, and stress health risk appraisal was collected at the beginning and end of semester on 67 subjects. HRV was collected using an infrared pulse plethysmograph ear sensor. Subjects completed the State-Trait Anxiety Inventory for Adults receiving a Stress Index score. Lifestyle education (breathing tech., attitude, and heart-brain connection (coherence)) and exercise were the primary focus of the curriculum. Mixed-Design Multivariate ANOVA was used to examine associations. RESULTS: There was a stat. sig. difference in R-R intervals between group and time (F(1,65) = 6.577, p = 0.013). The vac group had a greater increase than non-vac group. VO2 was stat. sig. from pre-to post-test (F(1,65) = 12.894, p = <0.001). While the non-vac group had a greater HRV at pre-test, their HRV did not increase at post-test but the vac group did. There were no stat. sig. differences for coherence or stress index. CONCLUSIONS: Results suggest improvement in VO2. While no difference between groups or from pre- to post-test for HRV, coherence, or stress index it should be emphasized that this health education course significantly improved VO2. While the literature is clear that vac produces at least acute inflammation which would decrease HRV, the literature is not as clear as to the long-term effects of vac. These results are more in line with Kerkutluoglu et. al that identify the decline in HRV following vac was temporary.

BackgroundEhlers-Danlos syndrome (EDS) encompasses a group of connective tissue disorders often extending beyond musculoskeletal involvement. Emerging evidence indicates a high prevalence of cardiovascular autonomic dysfunction in this population, yet systematic physiologic evaluations remain limited.ObjectiveTo characterize cardiovascular autonomic function in EDS using standardized autonomic testing and heart rate variability (HRV) indices, and to explore intrinsic autonomic coupling by correlating resting heart rate with HRV parameters.MethodsThis cross-sectional study included 30 clinically diagnosed patients with EDS and 30 age- and sex-matched healthy controls. Short-term HRV analysis (five-minute supine ECG) and standard autonomic testing, including head-up tilt, were performed under controlled laboratory conditions. HRV indices were derived using Fast Fourier Transform (FFT) algorithms. Group differences were evaluated with independent t-tests, and correlations between resting heart rate and HRV measures were analyzed using Pearson’s correlation.ResultsCompared with controls, patients with EDS exhibited higher resting heart rate (87.3±11.6 vs 75.2±9.8 bpm), lower parasympathetic time-domain indices (standard deviation of normal-to-normal intervals or SDNN 35.4±9.7 vs 49.1±11.4 ms; root mean square of successive differences (RMSSD; 20.7±6.9 vs 31.6±8.8 ms), and altered frequency-domain markers (low frequency (LF) power 671±205 vs 542±176 ms²; high frequency (HF) power 174±81 vs 272±106 ms²; LF/HF ratio 3.7±1.3 vs 1.8±0.7). Orthostatic intolerance was observed in 16 (53.3%) of the patients with EDS versus three (10%) of the controls. Correlation analysis revealed that in EDS, resting HR correlated negatively with SDNN (r=-0.45, p=0.01), RMSSD (r=-0.52, p<0.01), and HF power (r=-0.39, p=0.03), while showing a positive correlation with LF/HF ratio (r=0.58, p<0.001).ConclusionPatients with EDS had autonomic dysregulation, with sympathetic predominance and diminished vagal modulation. The intrinsic coupling between resting heart rate and HRV indices suggests impaired cardiovascular autonomic integration. HRV profiling is a valuable noninvasive biomarker for early identification and longitudinal monitoring of autonomic dysfunction in EDS, potentially enhancing disease characterization and guiding individualized therapeutic strategies.

ObjectiveLeisure-time physical activity (LTPA) has considerable benefits for cardiovascular health and longevity, while occupational physical activity (OPA) is associated with an elevated cardiovascular risk. This “health paradox” may be explained by different effects on the autonomic nervous system from OPA and LTPA. Thus, we aimed to investigate whether objectively measured OPA and LTPA are differentially associated with autonomic regulation among workers.MethodsThe study comprised 514 blue-collar workers from the Danish cohort DPHACTO. Physical activity (i.e. walking, climbing stairs, running and cycling) was assessed objectively using accelerometers worn on the thigh, hip and trunk over multiple working days. During this period, a heart rate monitor was used to sample heart period intervals from the ECG signal. Heart rate and heart rate variability (HRV) indices were analyzed during nocturnal sleep as markers of autonomic regulation. Multiple regression analysis was used to determine the main effects of OPA and LTPA and their interaction on heart rate and HRV, adjusting for multiple confounders.ResultsStatistically significant interaction was found between OPA and LTPA on heart rate (adjusted p<0.0001) and HRV indices in time (rMSSD, adjusted p = 0.004) and frequency-domains (HF, adjusted p = 0.022; LF, adjusted p = 0.033). The beneficial effect of LTPA on nocturnal heart rate and HRV clearly diminished with higher levels of OPA, and high levels of both OPA and LTPA had a detrimental effect.ConclusionWe found contrasting associations for objectively measured OPA and LTPA with heart rate and HRV during sleep. Differential effects of OPA and LTPA on autonomic regulation may contribute to the physical activity health paradox.

We examined if the change in heart rate variability during passive heat exposure is modified by hot water heat acclimation (HA). Sixteen healthy adults (28 ± 5 years, 5 females/11 males) underwent heat exposure in a water-perfused suit, before and after 7 days of HA (60 min at rectal temperature ≥38.6 °C). During passive heat exposure, heart rate, the standard deviation of NN intervals (SDNN), the square root of the mean squared differences of successive NN intervals (RMSSD), and the power in the high-frequency range (HF) were measured. No difference in heart rate (P = 0.22), SDNN (P = 0.87), RMSSD (P = 0.79), and HF (P = 0.23) was observed at baseline. The increase in HR (pre-HA, 43 ± 10; post-HA, 42 ± 9 bpm; P = 0.57) and the decrease of SDNN (pre-HA, -54.1 ± 41.0; post-HA, -52.2 ± 36.8 ms; P = 0.85), RMSSD (pre-HA, -70.8 ± 49.5; post-HA, -72.7 ± 50.4 ms; P = 0.91) and HF (pre-HA, -28.0% ± 14.5; post-HA, -23.2% ± 17.1%; P = 0.27) were not different between experimental visits at fixed increases in esophageal temperature. These results suggest that 7 consecutive days of hot water HA does not modify the change in heart rate variability indices during passive heat exposure. Novelty: It remains unclear if HA alters the change in heart rate variability that occurs during passive heat exposure. At matched levels of thermal strain, 7 consecutive days of hot water immersion did not modulate the change in indices of heart rate variability during passive heat exposure.

Role of heart rate variability analysis in differentiating patients with idiopathic REM sleep behaviour disorders from healthy subjects. A systematic review with meta-analysis.

Heart rate variability is reduced during acute uncomplicated diverticulitis

Heart rate variability (HRV) provides both linear and nonlinear autonomic proxies that can be informative of health status in fibromyalgia (FM), where sympatho-vagal abnormalities are common. This retrospective observational study aims to: 1. detect differences in correlation dimension (D2) between FM patients and healthy controls (HCs); 2. correlate D2 with standard HRV parameters; 3. correlate the degree of HRV changes using a global composite parameter called HRV grade, derived from three linear indices (SDNN = intervals between normal sinus beats; RMSSD = mean square of successive differences; total power), with FM clinical outcomes; 4. correlate all linear and nonlinear HRV parameters with clinical variables in patients. N = 85 patients were considered for the analysis and compared to 35 healthy subjects. According to standard diagnostic protocol, they underwent a systematic HRV protocol with a 5-min paced breathing task. Disease duration, pain intensity, mood, sleep, fatigue, and quality of life were assessed. Non-parametric tests for independent samples and pairwise correlations were performed using JMP (all p < 0.001). Mann-Whitney U found a significant difference in D2 values between FM patients and HCs (p < 0.001). In patients, D2 was associated with all HRV standard indices (all p < 0.001) and FM impairment (FIQ = -0.4567; p < 0.001). HRV grade was also associated with FM impairment (FIQ = 0.5058; p < 0.001). Combining different HRV measurements may help understand the correlates of autonomic dysregulation in FM. Specifically, clinical protocols could benefit from the inclusion and validation of D2 and HRV parameters to target FM severity and related dysautonomia.

Heart rate variability (HRV) is defined as the difference in the timing of intervals between successive heartbeats and is used as a surrogate measure to the responsiveness of the autonomic nervous system. A review and synthesis of HRV as an indicator of autonomic nervous system responsiveness to pharmacologic stimulation/blockade of sympathetic and/or parasympathetic nervous system branches have not been completed. The aim of this integrative review is to synthesize research examining pharmacological modulation of the autonomic nervous system and the response of time domain, frequency domain, and nonlinear measures of HRV. Sympathetic nervous system blockade resulted in a consistent decrease in the standard deviation of normal-normal interval metric across studies. Stimulation of the parasympathetic nervous system was associated with an increase in several time, frequency, and nonlinear HRV indices, whereas blockade of the parasympathetic nervous system led to a decrease in similar indices. Recommendations to improve the reproducibility of future HRV research are provided for standardization of recording, analysis, and metric decisions and more thorough reporting of HRV indices in published studies. Alterations in autonomic nervous system input to the cardiovascular system are associated with an increased risk for adverse patient outcomes and increased mortality; therefore, understanding the influence of pharmacologic autonomic nervous system modulation on HRV indices and important considerations for reproducible HRV research design will inform future translational research on cardiovascular risk reduction.

Physiological stress is human body's response to a challenge by multiple systems in the body, in which ANS (Autonomic Nervous System) plays key roles. This paper proposes a stress level evaluation method based on time-frequency domain analysis of HRV (Heart Rate Variability) features combining statistical optimization. The most reliable and efficient indicator to ANS is HRV features obtained from time and frequency domain analysis of R-R intervals recorded during the modified Stroop test. A BP Neural network is utilized to train HRV features selected by t-test and one-way Anova test and classify new samples into four stress level categories i.e. relaxed state, low stress, medium stress and high stress. Weighing factors in classification and number of neurons in hidden layer are considered for optimized network. The proposed method has been validated by experimental results.