Mean Square Successive Difference Research Articles

Discriminatory ability of perioperative heart rate variability in predicting postoperative complications in major urologic surgery: a prospective cohort study

We aimed to determine if continuous perioperative heart rate variability (HRV) monitoring could improve risk stratification compared to a short preoperative measurement in radical cystectomy patients. Electrocardiography (ECG) recordings were collected continuously preoperatively to discharge in 83 patients. Two, 5-min ECG signal segments (preoperative and at 24-h post ECG placement) were analyzed offline to extract HRV metrics. HRV metric discriminatory ability to identify patients with 30-day postoperative complications were analyzed using receiver operating characteristics curves. Sixty participants were included for analysis of which 27 (45%) developed a complication within 30 days postoperative. HRV was reduced in patients with complications. Postoperative standard deviation NN intervals and root mean square of successive differences had area under the curves (AUC) of 0.67 (95% CI 0.54 to 0.81) and 0.68 (95% CI 0.54 to 0.82), respectively. Significant discriminatory abilities were also reported for postoperative frequency metrics of absolute low frequency (LF) [AUC = 0.65 (95% CI 0.51 to 0.79)] and high frequency (HF) powers [AUC = 0.69 (95% CI 0.55 to 0.83)] and total power [AUC = 0.66 (95% CI 0.53 to 0.80)]. Postoperative acquired HRV metrics demonstrated improved discriminatory ability. Our findings suggest that longer-term perioperative HRV monitoring presents with superior ability to stratify complication risk.

Autonomic Rebound Following Maximal Exercise in Bodybuilders and Recreationally Active Participants

The off-season for natural bodybuilders (BB) is characterized by increased training loads and fluctuations in caloric intake, which may lead to insufficient recovery. The autonomic nervous system (ANS) plays a pivotal role in recovery. The purpose of this study was to evaluate resting ANS activity and recovery following a maximal exercise bout in off-season BB and compare them to those of recreationally active individuals. Fifteen males participated; 7 recreationally active (RA) (24.6 ± 2.1 years, 81.1 ± 10.8 kg) and 8 BB (21.8 ± 2.9 years, 89.3 ± 13.0 kg). Each performed a graded exercise test. Heart rate variability (HRV) was measured at rest and during a 45 min recovery period. HRV was analyzed as: root mean square of successive differences (lnRMSSD), standard deviation of normal-to-normal sinus beats (lnSDNN), high frequency (lnHF), low frequency (lnLF), and the ratio of low frequency to high frequency (lnLF/lnHF). A one-way ANOVA showed no differences for any resting marker of HRV, HR, and HR recovery. A significant depression in all markers of HRV was observed in the BB group at the 15 min point, and no recovery was observed before 45 min when compared to RA. The results of this study demonstrated depressed HRV recovery following the graded exercise test in BB when compared to the RA group.

Association of sex with heart rate variability in atrial fibrillation patients

Abstract Background Sex-specific differences in cardiac autonomic tone have not been thoroughly investigated in patients with atrial fibrillation (AF) but may play a relevant role. Purpose We aimed to investigate cardiac autonomic function of female compared to male AF patients by means of short-term heart rate variability (HRV) analysis. Methods In this cross-sectional analysis, we enrolled 1150 patients from the Swiss-AF cohort study with 5-minute resting ECG recordings in sinus rhythm. We calculated the following HRV parameters: HRV triangular index (HRVI), standard deviation of NN intervals (SDNN), root mean square of successive differences, mean heart rate, power in the high frequency and low frequency range. We fitted linear regression models to analyze the association between gender and HRV variables adjusted for age, intake of betablockers, hypertension, diabetes and heart failure. Results 361 patients (29%) were female (mean age 72.9±7.8 years), 789 (68.6%) were male (mean age 69.8±8.5 years). In the multivariable adjusted models, female sex was associated with significantly lower values of HRVI (β = -0.74; 95% CI -1.44- -0 04, p=0.039) and SDNN (β = 8.95; 95% CI 0.162-17.7, p=0.046). This association persisted in all three age tertiles (<68 years, 68-75 years and ≥ 75 years of age). Conclusions In an elderly AF cohort, female sex is associated with reduced global autonomic activity. Whether this is associated with an adverse prognosis has to be investigated.

Ultra-short-term deceleration capacity and heart rate variability as indicators of vagal denervation before and after pulmonary vein isolation

Abstract Introduction Pulmonary vein isolation (PVI) is a well-established therapy of atrial fibrillation (AF). However, subtypes of AF can differ and exact mechanisms in which patients benefit from PVI remain not fully understood. Parasympathetic activity can play important role in pathogenesis of AF. Moreover, catheter ablation can impact vagal innervation of the heart, nevertheless methods of periprocedural assessment of such impact of PVI are lacking. Purpose Ultra-short-term deceleration capacity (UST-DC) and ultra-short-term heart rate variability (UST-HRV) were investigated to determine their potential function as indicators of parasympathetic activity before and after PVI. Methods 24 consecutive patients (8 females, age 54±11) with paroxysmal AF were included in the study. UST-DC and UST-HRV were calculated from 1-minute ECG recordings performed before and after PVI. Results There was a significant differences between UST-DC before PVI vs after PVI (7.6ms vs 2.8ms; p=0.0000018) and between UST-HRV parameters before and after PVI: standard deviation of normal-to-normal (UST-SDNN) (37.8ms vs 18.4ms; p=0.00005), root mean square of successive differences (UST-rMSSD) (25.3ms vs 12.2ms; p=0.00083) and proportion of success NN intervals differing more than 50ms divided by total number of NNs (UST-pNN50) (8.4% vs 2%; p=0.045). Heart rate (HR) increase was also statistically significant (pre-PVI vs post-PVI, 65.5bpm vs 73.7bpm; p=0.016). After 3-months patients with baseline UST-DC>7.5ms, were less likely to experience AF recurrence when compared to patients with baseline UST-DC<7.5ms (0% vs 31%, p=0.0496). In these groups difference in AF recurrences after 12-months of follow-up did not meet statistical significance (36% vs 38%, p=0.52). No correlation between UST-HRV parameters and AF recurrence during follow up was observed. Conclusions PVI leads to significant changes in UST-DC and UST-HRV and these parameters may serve as indicators of vagal denervation after AF ablation. Patients with more prominent baseline UST-DC are less likely to experience AF recurrence during 3-month blanking period after PVI.

Emotion Dynamics among Late Adolescents and Emerging Adults: The Role of Maternal Privacy Invasion Perceptions.

Prior research suggests that youth experience immediate emotional distress following privacy invasion, but it is unclear whether and how persistent privacy invasion over longer periods destabilizes the intrapersonal emotional regulatory functions that privacy serves. This study investigated whether late adolescents and emerging adults who reported different patterns of maternal privacy invasion over a full academic year showed differences in emotion regulation, as reflected by the frequency and lability of negative and positive emotional experiences. Participants were first-year university students (n = 349; 60.2% female) in Hong Kong, aged 17 to 24 (MT1 = 18.20, SDT1 = 1.10). They self-reported maternal privacy invasion perceptions and negative and positive emotions 16 times, at bi-weekly intervals. Latent class growth analyses divided participants into a Higher Invasion Perceptions group (24.9%), a Moderate Invasion Perceptions group (46.4%), and a Lower Invasion Perceptions group (28.7%). A one-way MANCOVA examined potential differences in negative and positive emotion dynamics across groups, indexed by frequency (means) and instability (mean square of successive differences and probability of acute change). In line with predictions, both the Higher Invasion and Moderate Invasion groups reported higher negative emotion frequency and instability, compared to the Lower Invasion group. However, groups showed no significant differences regarding positive emotion frequency and instability. The findings indicate that perceptions of maternal privacy invasion predict youth's negative emotion regulation processes over their first collegiate year. Prolonged, higher levels of maternal privacy invasion may disrupt the intrapersonal regulatory functions that privacy serves over time.

Acute Autonomic Nervous System Response to Direct Sacral Nerve Root Stimulation in Lower Urinary Tract Dysfunction: A New Approach to Understand the Mechanism of Action of Sacral Nerve Modulation.

Our goal was to assess acute autonomic nervous system (ANS) response to direct sacral nerve root (SNR) stimulation in the context of lower urinary tract dysfunction. In this retrospective monocentric study, patients undergoing 2-stage sacral nerve modulation for overactive bladder, nonobstructive urinary retention, or chronic bladder pain syndrome between March 2022 and June 2023 were analyzed. A standardized stimulation protocol was applied during the lead implantation, each of the 4 contact points being sequentially stimulated at the amplitude required to elicit anal motor response. Stimulations were labeled as StimA, StimB, StimC, and StimD, ordered by ascending order of minimum amplitude required for anal motor response. Heart rate variability parameters were collected using PhysioDoloris Monitor, and computed through the time-domain (standard deviation of normal-to-normal intervals [SDNN], root mean square of successive differences), the frequency-domain (low frequency, high frequency) and the graphical (Analgesia Nociception Index [ANI]) methods. Fifty patients were analyzed, including 35 females. Twelve patients had an underlying neurological disease. Efficacy was deemed achieved in 54% of patients. SDNN variability significantly increased during StimA to StimC, while maximum SDNN significantly increased only during StimA. ANI variability significantly increased during all 4 stimulations, while maximum ANI significantly increased only during StimA. Direct stimulation of SNR is responsible for a significant increase in ANS and relative parasympathetic nervous system activity, with a greater effect observed when the stimulation was delivered closer to the SNR. These results shed light on potential mechanisms underlying sacral nerve modulation, particularly regarding the treatment of ANS dysregulation in lower urinary tract dysfunction.

Exploring physiological stress response evoked by passive translational acceleration in healthy adults: a pilot study utilizing electrodermal activity and heart rate variability measurements.

Passive translational acceleration (PTA) has been demonstrated to induce the stress response and regulation of autonomic balance in healthy individuals. Electrodermal activity (EDA) and heart rate variability (HRV) measurements are reliable indicators of the autonomic nervous system (ANS) and can be used to assess stress levels. The objective of this study was to investigate the potential of combining EDA and HRV measurements in assessing the physiological stress response induced by PTA. Fourteen healthy subjects were randomly assigned to two groups of equal size. The experimental group underwent five trials of elevator rides, while the control group received a sham treatment. EDA and HRV indices were obtained via ultra-short-term analysis and compared between the two groups to track changes in the ANS. In addition, the complexity of the EDA time series was compared between the 4s before and the 2-6s after the onset of PTA to assess changes in the subjects' stress levels in the experimental group. The results revealed a significant increase in the skin conductance response (SCR) frequency and a decrease in the root mean square of successive differences (RMSSD) and high frequency (HF) components of HRV. In terms of stress assessment, the results showed an increase in the complexity of the EDA time series 2-6s after the onset of PTA. These results indicate an elevation in sympathetic tone when healthy subjects were exposed to a translational transport scenario. Furthermore, evidence was provided for the ability of EDA complexity to differentiate stress states in individual trials of translational acceleration.

Does cardiovascular autonomic modulation correspond to the increase in dim-light onset of melatonin? A preliminary analysis

Introduction: The endogenous circadian system promotes the rise in melatonin approximately every 24 hours. In the laboratory, dim light melatonin onset (DLMO) is used as the gold standard method to assess circadian phase. Exogenous melatonin affects cardiac sympathovagal balance and vasomotor sympathetic modulation. Whether or not the endogenous increase in melatonin corresponds to changes in cardiovascular autonomic modulation is unclear. Objective: To evaluate if the timing of DLMO corresponds to the timing of changes in cardiovascular autonomic indices. Methods: Five healthy adults (3 females, age 23.8±SD1.8 y) completed a minimum of four nights of sleep regularization by maintaining a self-selected 8h in bed each night before the experiment. The day after regularization, they reported to the laboratory ~8 hours before bedtime. Measurements for melatonin and cardiovascular autonomic modulation started 6 hours before bedtime and continued 1 hour after. Saliva samples were collected every 30 minutes. At the end of every hour, 10 minutes of continuous R-R intervals (R-R) and systolic blood pressure (SBP) were recorded via electrocardiogram and beat-to-beat finger photoplethysmography, respectively. As currently established, DLMO was defined as the interpolated time for melatonin increase over 3pg/ml. Cardiovascular autonomic indexes were run through CardioSeries v.2 to create a temporal series for R-R interval and systolic blood pressure. Cardiac autonomic modulation was assessed by applying the spectral analysis using the fast Fourier transformation method and time domain analysis of heart rate variability (HRV) and spectral analysis of blood pressure variability (BPV). For each autonomic index, data were plotted and fitted with a segmental linear regression to reveal the intercept of the two segments to define the autonomic onset (AO). A paired t-test compared the difference between DLMO and AO times. Bland-Altman plots with a 95% limit of agreement (LOA) identified the distribution of differences between the methods. Additionally, a one-sample t-test compared the differences between methods to a fixed time clock range. Data are shown as mean ± SD and significance was set as p<0.05. Results: AO time calculated for all indexes from HRV and BPV were not statistically different compared to DLMO time (R-R: +16±86 mins, P=0.70; root mean square of successive differences (RMSSD): -20±91 mins, P=0.67; low frequency (LF) nu: +29±52 mins, P=0.74; high frequency (HF) nu: -43±91 mins, P=0.23; LFHF: -26±73 mins, P=0.47; SBP: -14±104 mins, P=0.78; LFSBP: -6±107 mins, P=0.90). The Bland Altman plots did not identify any systematic difference between AO and DLMO times. The smallest difference was LFnu with a LOA 95% from -73 to +131 minutes, while the largest difference was LFSBP with LOA 95% from -217 to +204 minutes. Additionally, the difference between DLMO and AO LFnu times (LFnu: +29±52) was statistically similar from -36 to +95 minutes. Conclusion: In young healthy adults, our preliminary data shows that AO times of cardiovascular autonomic indexes correspond to salivary DLMO. A larger dataset with more frequent simultaneous measurements of melatonin and cardiovascular autonomic modulation are essential to confirm our preliminary findings. Medical Research Foundation of Oregon, OHSU OFDIR, R01HL163232. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The effectiveness of a standardized tobacco cessation program on psychophysiological parameters in patients with addiction undergoing long-term rehabilitation: a quasi-experimental pilot study.

Although there is a very high comorbidity between tobacco dependence and other addictive disorders, there are only few studies examining the implementation and outcomes of a tobacco cessation program in patients with addictive diseases. Therefore, the aim of this study is to investigate to what extent a standardized tobacco cessation program leads to improvements regarding psychological/physical parameters in patients with addiction undergoing therapy and whether there is a reduction in tobacco consumption. The study took place in a therapeutic community specialized in addiction therapy. A total sample of 56 participants were non-randomly assigned to an intervention group (IG; n = 31) and a treatment as usual group (TAUG; n = 25). The IG participated in a 6-week tobacco cessation program, while the TAUG received no additional treatment. Both groups were assessed for changes in primary outcomes (tobacco dependence, smoked cigarettes per day (CPD), and general substance-related craving) and secondary outcomes (heart rate variability (HRV): root mean square of successive differences, self-efficacy, and comorbid psychiatric symptoms) at two measurement time points (pre- and post-treatment/6weeks). We observed significant improvements in self-efficacy (F(1,53) = 5.86; p < .05; ηp2 = .11) and decreased CPD in the IG (β = 1.16, ρ < .05), while no significant changes were observed in the TAUG. No significant interaction effects were observed in psychiatric symptoms, general substance-related craving, and HRV. The results highlight the potential benefit of an additional tobacco cessation program as part of a general addiction treatment. Although no improvements in the physiological domain were observed, there were significant improvements regarding self-efficacy and CPD in the IG compared to the TAUG. Randomized controlled trials on larger samples would be an important next step. ISRCTN15684371.

The Influence of Perceived Discrimination on Heart Rate Variability in Young Black Adults

Introduction: Cardiovascular disease (CVD) is the leading cause of death in the United States, with a disproportional precedence in Black adults. Heart rate variability (HRV) is used to help predict future CVD, with lower HRV indicative of a compromised cardiovascular system. Prior evidence has suggested that experienced racial discrimination is associated with CVD risk. However, there is limited information regarding experienced racial discrimination on HRV in young Black adults. Purpose/hypothesis: The purpose of this study was to determine whether personal-level and group-level racial discrimination was associated with worse HRV in young Black adults. Methods: Black adults aged 18-25 (n=18, 44.45% female) volunteered to participate in this study, arriving at the lab at 7am in a fasted state. Following 30 minutes of rest, HRV measures were assessed using a SphygmoCor 3-lead ECG in a supine position. The HRV measure included the standard deviation of all R-R intervals (SDNN), the mean number of times an hour successive NN intervals exceeds 50ms (pNN50), the root mean square of successive differences (RMSSD), the low-frequency (LF) power domain, high-frequency (HF) power domain, and their ratio (LF:HF). Participants were given a perceived racial discrimination questionnaire that assessed personal-level and group-level discrimination. Pearson correlations were used to analyze the association between perceived racial discrimination measures and HRV measures. Results: In Black males, perceived personal-level racial discrimination was negatively associated with sympathetic activity (LF, R2 = -0.704, p = 0.023) and sympathovagal balance (LF:HF, R2 = -0.749, p = 0.013), and positively associated with parasympathetic activity (HF, R2 = 0.704, p = 0.023). Perceived group-level racial discrimination was not associated with HRV measures. Furthermore, perceived racial discrimination was not associated with HRV in Black females. Conclusion: Although decreased HRV has been associated with increased risk for CVD, higher HRV has been shown to be associated with left ventricular mass in Black adults. Therefore, HRV implications may be dependent on social determinants of health and other covariates that are associated with race/ethnicity. In the current study, higher HRV was observed in Black males who reported higher personal-level discrimination, which may be an important factor in sympathetic and parasympathetic cardiac control and CVD risk. Given our preliminary findings, more research is warranted that investigates the impact of racial identity, resiliency, coping, and healthy lifestyle behaviors on mitigating the detrimental impact of perceived racial discrimination on the cardiovascular health of young Black adults. Summer Undergraduate Research Fellowship Recipient from the American Physiological Society. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Activation of cardiac parasympathetic and sympathetic activity occurs at different skin temperatures during face cooling.

Sufficiently cold-water temperatures (<7°C) are needed to elicit the sympathetic response to the cold pressor test using the hand. However, it is not known if stimulating the trigeminal nerve via face cooling, which increases both sympathetic and cardiac parasympathetic activity, also has a threshold temperature. We tested the hypothesis that peak autonomic activation during a progressive face cooling challenge would be achieved when the stimulus temperature is ≤7°C. Twelve healthy participants (age: 25 ± 3 yr, four women) completed our study. Six pliable bags, each containing water or an ice slurry (34°C, 28°C, 21°C, 14°C, 7°C, and 0°C) were applied sequentially to participants' forehead, eyes, and cheeks for 5 min each. Mean arterial pressure (photoplethysmography; index of sympathetic activity) and heart rhythm (3-lead ECG) were averaged in 1-min increments at the end of baseline and throughout each temperature condition. Heart rate variability in the time [(root mean square of successive differences (RMSSD)] and frequency [high-frequency (HF) power] domains was used to estimate cardiac parasympathetic activity. Data are presented as the increase from baseline ± SD. Mean arterial pressure only increased from baseline in the 7°C (13.1 ± 10.3 mmHg; P = 0.018) and 0°C (25.2 ± 7.8 mmHg; P < 0.001) conditions. Only the 0°C condition increased RMSSD (160.6 ± 208.9 ms; P = 0.009) and HF power (11,450 ± 14,555 ms2; P = 0.014) from baseline. Our data indicate that peak increases in sympathetic activity during face cooling are initiated at a higher forehead skin temperature than peak increases in cardiac parasympathetic activity.

Maternal Injection with Dexamethasone Results in Female-Biased Autonomic Dysregulation in Rat Offspring

Autonomic dysfunction is an underlying risk factor for cardiovascular disease (CVD). Maternal injection of the synthetic GC dexamethasone (DEX) during the last 4 days of gestation results in female-biased increases in stress-responsive pressor (MAP), heart rate (HR) and altered heart rate variability (HRV) in adult rat offspring, suggesting a role for GC-mediated programming of autonomic function. The present study used pharmacological antagonists for adrenergic (SYM) or cholinergic (PS) receptors to investigate the degree to which changes in SYM or PS activity underlie the autonomic dysfunction in offspring of dams injected with DEX during late gestation. Naïve breeders were injected with DEX (0.4mg/kg/day, s.c.) or vehicle (hydroxypropyl beta cyclodextrin; Veh) on gestation days 18-21. Radiotelemetry was used in adult offspring for recording HR, MAP, and HRV (root mean square of successive differences: RMSSD). At 10-11 weeks rats were randomly assigned to receive SYM antagonists, α-adrenoceptor (prazosin; 0.5mg/kg, i.p.) + β-adrenoceptor (atenolol; 1mg/kg, i.p.), a PS antagonist (homatropine methylbromide; 0.2mg/kg, i.p), or saline (SAL, i.p.). Evaluations were made over 20 min following injection and then during a 20 min restraint. Females were tested on diestrus. In utero DEX exposure resulted in significantly lower RMSSD, an index of vagal tone, in DEX-exposed females and males. PS blockade significantly reduced RMSSD in Veh-, but not DEX-exposed female offspring. SYM blockade did not influence RMSSD in females. In males, PS blockade reduced in RMSSD in both DEX- and Veh-exposed offspring. SYM blockade only reduced RMSSD in males exposed to DEX. Area under the curve (AUC) analysis revealed that in female offspring, SYM blockade resulted in a greater reduction in HR in DEX-exposed offspring, compared to Veh (DEX-SYM: −220 bpm vs. DEX-SAL; Veh-SYM: −197 bpm vs. VEH-SAL) and during restraint (DEX-SYM: −535 bpm vs. DEX-SAL; Veh-SYM: −342 bpm vs. VEH-SAL). PS blockade resulted in a greater increase in HR in Veh-exposed females both following the injection (Veh-PS: −187 bpm vs. VEH-SAL; DEX-PS: −101 bpm vs. DEX-SAL) and during restraint (Veh-PS: −161 bpm vs. VEH-SAL; DEX-PS: −61 bpm vs. DEX-SAL). AUC analysis for MAP showed similar responses to those for HR with SYM blockade having a greater impact in DEX-exposed females and PS blockade having a greater effect in Veh-exposed females. By contrast, in male offspring in utero DEX exposure did not influence HR or MAP responses to SYM or PS blockade. Overall, these findings suggest that maternal DEX injections alter autonomic development primarily in in female offspring and is characterized by a shift from PS to SYM predominance. Better understanding of the mechanisms involved in this programming are important for identifying individuals at risk for CVD and development of interventional strategies for prevention of CVD. Funding: NIH U54 MH118919. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Ventilatory Variability Is Increased at Rest in Pulmonary Arterial Hypertension

Ventilatory instability is associated with adverse outcomes in left heart failure, with periodic breathing during awake, rest, sleep and exercise (exercise oscillatory ventilation) associated with increased mortality. Increased peripheral and central chemoreflex sensitivities and impairment of cardiac output have been implicated as causative mechanisms of ventilatory instability in heart failure. As these factors are also present in pulmonary arterial hypertension (PAH), we tested the hypothesis that variability of breath-by-breath ventilation at rest would be increased in PAH compared with healthy controls. In fourteen patients with PAH (9 female, age 48.4±12.8 years, mean ± SD) and 14 healthy participants (9 female, age 49.4±14.2 years) breath-by-breath measurement of tidal volume and breathing frequency was undertaken with a pneumotachometer connected via a mouthpiece with nose-clip for 10 minutes while they rested awake and supine. Ventilatory (V̇E) variability was assessed using root mean square of successive differences (RMSSD), standard deviation (SD), average real variability (ARV, i.e., sum of absolute differences in successive observations), coeffcient of variation (CoV), as well as Poincaré analysis and compared between PAH and healthy controls (Student’s t-test). Correlations between measures of ventilatory variability and pulmonary hemodynamic characteristics, exercise capacity and function were assessed with Pearson’s correlation coeffcient. Resting V̇E was higher in PAH compared to healthy controls (14.3±1.1 and 12.1±0.5 L·min−1 respectively; p=0.009). Measures of variability for V̇E were increased in PAH compared to healthy controls. More specifically, RMSSD (3.59±1.36 vs. 2.48±0.87 L·min−1, p=0.017), SD (2.92±1.14 vs. 1.98±0.53 L·min−1, p=0.012), ARV (2.47±0.97 vs. 1.67±0.60 L·min−1, p=0.016), Poincaré SD1 (short-term variability, p=0.020) and SD2 (long-term variability, p=0.028) were increased in PAH compared to healthy controls, respectively. No correlations were found between measures of ventilatory variability and pulmonary hemodynamics (mean pulmonary artery pressure, pulmonary vascular resistance, and cardiac output), six-minute walk distance or WHO functional class. In summary, resting ventilatory variability is increased in PAH and not associated with haemodynamic factors and exercise capacity. Whether such raised ventilatory variability in PAH is related to increased chemoreflex sensitivity requires exploration. This study received funding support from the Greenlane Research and Educational Fund (21/01/4153), Health Research Council of New Zealand (19/687), and the Sidney Taylor Trust. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex difference in cardiac autonomic function in African American adults

African American (AA) individuals in the United States have the highest prevalence of hypertension, with an age-adjusted prevalence of 55.8% in AA men and 56.9% in women. Compared to other racial groups, the AA population also has a two- to three-fold higher mortality rate resulting from hypertension-related causes. Furthermore, AA men exhibit a higher mortality rate than AA women. Previous studies have demonstrated sex differences in some biological mechanisms linked to the increased cardiovascular disease risk in the AA population —such as impaired vascular function and elevated oxidative stress. However, it is unknown whether sex differences are present in baroreflex sensitivity (BRS) and heart rate variability (HRV), which are key mechanisms that may contribute to the pathogenesis and clinical outcomes of hypertension. Herein, we tested the hypothesis that young AA men exhibit impaired cardiac autonomic function (spontaneous BRS and HRV) compared to AA women. We studied 26 young normotensive AA adults (13 women) [Age (men: 22 ± 3; and women: 19 ± 1yr; mean ± SD, p = 0.03); BMI (men: 24 ± 3; and women: 24 ± 2 kg/m2; p = 0.92)]. Heart rate (HR; ECG) and beat-to-beat blood pressure (BP; finger plethysmography) were continuously recorded during 10 min of rest to assess HRV and cardiac BRS. Resting HR (men, 61 ± 8; and women: 65 ± 9 bpm; p = 0.18), diastolic BP (men, 66 ± 6; and women: 65 ± 5 mmHg; p = 0.48) and respiratory rate (men, 17 ± 3; and women, 17 ± 3 bpm; p = 0.97) were similar between the groups. Mean BP and systolic BP were higher in AA men, though within the normotensive range for both groups [mean BP (men: 84 ± 5; and women: 76 ± 5 mmHg; p = 0.001); SBP (men: 119 ± 4; and women: 103 ± 7 mmHg; p &lt; 0.001)]. HRV [root mean square of successive differences between normal heartbeats (RMSSD); men, 113 ± 78; and women, 79 ± 43 ms; p = 0.18] and cardiac BRS (overall gain; men, 25 ± 13; and women, 28 ± 12 ms/mmHg; p = 0.66) were not different between groups. These results indicate that BRS and HRV, which are markers of cardiac autonomic regulation, do not differ based on sex among young normotensive African American individuals. Supported by: Kinesiology and Health Education UT Austin Start-up Account 19-2635-91; and TACSM 2023 Student Research Development Award. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Examination of Cardiac Activity with ECG Monitoring Using Heart Rate Variability Methods.

The paper presents a system for analyzing cardiac activity with the possibility of continuous and remote monitoring. The created sensor mobile device monitors heart activity by means of the convenient and imperceptible registration of cardiac signals. At the same time, the behavior of the human body is also monitored through the accelerometer and gyroscope built into the device, thanks to which it is possible to signal in the event of loss of consciousness or fall (in patients with syncope). Conducting real-time cardio monitoring and the analysis of recordings using various mathematical methods (linear, non-linear, and graphical) enables the research, accurate diagnosis, timely assistance, and correct treatment of cardiovascular diseases. The paper examines the recordings of patients diagnosed with arrhythmia and syncope recorded by electrocardiography (ECG) sensors in real conditions. The obtained results are subjected to statistical analysis to determine the accuracy and significance of the obtained results. The studies show significant deviations in the patients with arrhythmia and syncope regarding the obtained values of the studied parameters of heart rate variability (HRV) from the accepted normal values (for example, the root mean square of successive differences between normal heartbeats (RMSSD) in healthy individuals is 24.02 ms, while, in patients with arrhythmia (6.09 ms) and syncope (5.21 ms), it is much lower). The obtained quantitative and graphic results identify some possible abnormalities and demonstrate disorders regarding the activity of the autonomic nervous system, which is directly related to the work of the heart.

Exploratory analysis of spontaneous versus paced breathing on heart rate variability in veterans with combat-related traumatic injury.

Respiration is a crucial determinant of autonomic balance and heart rate variability (HRV). The comparative effect of spontaneous versus paced breathing on HRV has been almost exclusively explored in healthy adults and never been investigated in an injured military cohort. To examine the effect of spontaneous versus paced breathing on HRV in veterans with combat-related traumatic injury (CRTI). Observational cohort study. ArmeD serVices trAuma rehabilitatioN outComE (ADVANCE) study, Stanford Hall, UK. The sample consisted of 100 randomly selected participants who sustained CRTI (eg, amputation) during their deployment (Afghanistan 2003-2014) and were recruited into the ongoing ADVANCE prospective cohort study. Not applicable. HRV was recorded using a single-lead ECG. HRV data were acquired during a sequential protocol of 5-minute spontaneous breathing followed immediately by 5 minutesof paced breathing (six cycles/minute) among fully rested and supine participants. HRV was reported using time domain (root mean square of successive differences), frequency domain (low frequency and high frequency) and nonlinear (sample entropy) measures. The agreement between HRV during spontaneous versus paced breathing was examined using the Bland-Altman analysis. The mean age of participants was 36.5 ± 4.6 years. Resting respiratory rate was significantly higher with spontaneous versus paced breathing (13.4 ± 3.4 vs. 7.6 ± 2.0 breaths/minute; p < .001), respectively. Resting mean heart rate and root mean square of successive differences were significantly higher with paced breathing than spontaneous breathing (p < .001). Paced breathing significantly increased median low frequency power than spontaneous breathing (p < .001). No significant difference was found in the absolute power of high frequency between the two breathing protocols. The Bland-Altman analysis revealed poor agreement between HRV values during spontaneous and paced breathing conditions with wide limits of agreement. Slow-paced breathing leads to higher HRV than spontaneous breathing and could overestimate resting "natural-state" HRV.

Vagal tone, pain sensitivity and exercise-induced hypoalgesia: The effect of physical activity level.

Vagal activity has analgesic effects that are attributed to exercise-induced hypoalgesia (EIH). High vagal tone and low pain sensitivity are reported in individuals who routinely exercise yet, their association is unclear. Furthermore, it is unknown if the heightened vagal tone following high physical activity predicts and intensifies EIH. Fifty-one healthy participants (27 low-moderately physically active; 27 females) underwent a resting-state electrocardiogram followed by heart rate variability analysis. Pain measurements, including pressure (PPT) and heat (HPT) pain thresholds, ratings of tonic heat pain (THP) and conditioned pain modulation (CPM) paradigm, were conducted pre- and post-exercise on a cycle ergometer. The highly active group demonstrated higher vagal tone compared to the low-moderately active (root mean square of successive differences between R-R intervals: 63.96.92 vs. 34.78 ms, p = 0.018; percentage of successive R-R intervals that exceed 50 ms: 24.41 vs. 11.52%, p = 0.012). Based on repeated-measure ANOVA, the highly active group showed higher PPT at pre-exercise, compared to the low-moderately active group (382 kPa vs. 327 kPa; p = 0.007). Post-exercise, both groups demonstrated EIH, increased HPT (p = 0.013) and decreased THP ratings (p < 0.001). Linear regression revealed that only in the low-moderately active group, higher vagal tone was associated with more efficient pre-exercise CPM and a greater reduction in THP ratings post-exercise (p ≤ 0.01). Highly active individuals demonstrate greater vagal tone and lower pain sensitivity but no greater EIH. Vagal tone moderates pain inhibition efficiency and EIH only in low-moderately active individuals. These findings suggest that physical activity level moderates the vagal-pain association via the endogenous analgesia system. Highly physically active individuals exhibit greater vagal tone and reduced sensitivity to experimental pain, yet they do not benefit more from exercise-induced hypoalgesia (EIH) compared to low-moderately active individuals. Moreover, low-moderately active individuals with greater vagal tone exhibited more efficient endogenous pain inhibition and greater EIH, suggestive of the moderation effect of physical activity level on vagal-pain associations.

Loneliness dynamics and physical health symptomology among midlife adults in daily life.

The current study examined how average daily loneliness (between-persons [BPs]), intraindividual variability in loneliness across days (within-persons [WPs]), and loneliness stability informed physical health symptomatology. We utilized daily diary data from a national sample of 1,538 middle-aged adults (Mage = 51.02; 57.61% women) who completed eight end-of-day telephone interviews about daily experiences, including loneliness and physical health symptoms (e.g., headaches, nausea). Via multilevel modeling, we examined average daily loneliness (BPs), intraindividual variability in loneliness (WPs), stability in loneliness (individual mean-squared successive difference) in association with the number and average severity of daily physical health symptoms. When participants were less lonely on average, and on days when loneliness was lower than a person's average, they had fewer and less severe physical health symptoms. Additionally, participants who were more stable in loneliness across 8 days had less severe physical health symptoms. Further, there was a stronger association between instability in loneliness and more physical health symptoms for people who were lonelier on average. Finally, the increase in physical health symptom severity associated with WP loneliness was strongest for participants with low variability in loneliness. Loneliness is associated with physical health symptoms on a day-to-day basis, especially for people who are highly variable in loneliness. Considerations of multiple sources of variation in daily loneliness may be necessary to adequately address loneliness and promote health. Public health interventions addressing loneliness may be most effective if they support social connectedness in people's everyday lives in ways that promote stable, low levels of loneliness. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

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

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

Psychological Stress Analysis to Evaluate the Effects of Transcranial Magnetic Stimulation on Mood Regulation and Quality of Life in Patients with Bipolar Disorder.

To explore the impact of transcranial magnetic stimulation on emotion regulation and quality of life in patients with bipolar disorder (BD) and to evaluate the effectiveness of the mental stress analyzer. Patients with BD admitted to our hospital from August 2022 to August 2023 were retrospectively selected. For the present study, 60 patients who received drug therapy served as the control group, and the other 60 patients who received repeated transcranial stimulation on this basis served as the observation group. The heart rate variability (HRV) of the two groups of patients was detected by a mental stress analyzer/HRV analysis system. Hamilton Depression Rating Scale (HAMD), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) were used to evaluate the mental state of the two groups of patients. The quality of life of the two groups was assessed using the Comprehensive Quality of Life Questionnaire 74 (GQOLI-74). Clinical effectiveness global rating scale-illness severity (CGI-SI) was used to evaluate the clinical symptoms of the two groups of patients, and the incidence of adverse reactions was calculated. In comparison to the control group, the high-frequency power (HF) of the patients demonstrated an elevation in the observation group, and the low-frequency power (LF) and LF/HF were significantly reduced (p < 0.05). The standard deviation of NN intervals (SDNN), standard deviation of all five-minute NN intervals (SDANN), root mean square of successive differences (rMSSD), and percent RR intervals with a difference in duration higher than 50 ms (PNN50) of patients in the observation group showed a notable increase compared to the control group (p < 0.05). Compared with the control group, the HAMD, SAS, and SDS scores of the patients in the observation group demonstrated a substantial decline relative to the control group (p < 0.05). In contrast to the control group, there was a significant increase in the overall clinical effectiveness rate among patients in the observation group, and the incidence of adverse reactions was significantly reduced (p < 0.05). Repetitive transcranial magnetic stimulation (rTMS) has significant clinical effects in treating BD and can effectively improve patients' anxiety, suppress emotions, and regulate patients' emotions. At the same time, rTMS has high safety and little impact on the balance of patients' autonomic nervous function, reduces the incidence of adverse reactions, accelerates the patient's recovery process, and is suitable for clinical promotion.