Age and ethnicity differences in short-term heart-rate variability

Cardiac autonomic function in young, healthy adults: Influence of race and sex

Non-Hispanic Black (BL) adults living in the United States are more likely to develop cardiovascular disease (CVD) compared with their non-Hispanic White (WH) counterparts. Although measures of cardiac autonomic function [i.e., spontaneous cardiac baroreflex sensitivity (BRS) and heart rate variability (HRV)] have a predictive value for CVD, studies investigating racial differences in cardiac autonomic function are limited and have reported conflicting results. Furthermore, sex differences are often not considered despite BL women having a high prevalence of CVD. We hypothesized that young BL men and women would exhibit lower cardiac BRS and HRV compared with their WH counterparts. Heart rate and beat-to-beat blood pressure were continuously recorded during 5 min of supine rest in 145 young (18-33 yr), healthy, BL (37 men, 38 women) and WH (39 men, 31 women) adults to assess cardiac BRS and HRV. Overall cardiac BRS (sequence method) was higher in BL adults compared with WH adults (P < 0.001), which was mainly driven by differences between BL and WH men (BL men: 34 ± 16 vs. WH men: 21 ± 9 ms/mmHg, P < 0.001) compared with women (BL women: 27 ± 12 vs. WH women: 24 ± 11 ms/mmHg; P > 0.05). Likewise, greater HRV in BL adults, indexed by root mean square of successive differences, was primarily driven by BL men (BL men: 109 ± 59 vs. WH men: 64 ± 33 ms; P < 0.001) rather than BL women (P > 0.05). Thus, contrary to our hypothesis, these results support that reduced cardiac autonomic function does not manifest early in life among young BL adults.NEW & NOTEWORTHY Herein, we demonstrated that BL adults do not have lower cardiac autonomic function compared with WH adults. Rather BL men had greater spontaneous cardiac baroreflex sensitivity and heart rate variability compared with WH men while no differences were found among BL and WH women. These findings suggest that reduced cardiac autonomic function, which could increase the risk of cardiovascular disease, does not appear early in life in healthy BL adults.

The interplay between heart rate variability, inflammation, and lipid accumulation: Implications for cardiometabolic risk

Deleterious adiposity (e.g., obesity) is considered an inflammatory condition that increases risk for cardiovascular diseases. Lower heart rate variability (HRV), an independent predictor of cardiovascular disease risk, is linked with higher levels of adiposity and inflammation. However, indices of adiposity vary in their strength of association with disease risk. Body mass index (BMI) is a modest predictor of disease, while the lipid accumulation product (LAP) better predicts disease risk. The current investigation used cross-sectional and prospective designs to probe the differential associations between HRV and multiple measures of adiposity (e.g., LAP and BMI) and examine if inflammation (measured via C-reactive protein; CRP) mediated these associations. Study 1 showed that HRV was more strongly linked with LAP relative to other adiposity measures and that this link was mediated by CRP. Study 2 replicated Study 1 results and showed that this association remained significant 4 years later. Our novel findings are consistent with studies suggesting LAP may be a superior measure of cardiovascular disease risk relative to other measures of adiposity. Importantly, the strong link between HRV and LAP was mediated by inflammation, highlighting the key role of the cholinergic anti-inflammatory pathway in regulating obesity and associated health consequences.

Lower heart rate variability is associated with loss of muscle mass and sarcopenia in community-dwelling older Chinese adults

BACKGROUND/PURPOSE

Autonomic nervous system (ANS) disorders may occur in skeletal muscle disease, but the link between them has not been fully established. Studying the relationship between them may yield insights into the mechanisms and treatment of disease. This study aimed to explore the association between heart rate variability (HRV), sarcopenia, and subscales of sarcopenia (muscle mass, muscle strength, and physical mobility).

METHODS

2514 community-dwelling older Chinese participants were included in this study. The Asian Working Group for Sarcopenia guidelines were used to define sarcopenia. HRV was measured by 90-s electrocardiogram RR interval data. All HRV parameters were transformed using natural logarithms. Multiple regression analysis and multivariate linear regression was performed using potential correlates.

RESULTS

The overall prevalence of sarcopenia was 15.1 % (18.5 % in males and 12.6 % in females). In the logistic regression analysis model, there was a significant association between log-transformed standard deviation of RR interval (lnSDNN) (OR = 0.736, p = 0.019), log-transformed coefficient of variation of RR intervals (lnCVRR) (OR = 0.751, p = 0.020), log-transformed low-frequency power (lnLF) (OR = 0.861, p = 0.008), log-transformed high-frequency power (lnHF) (OR = 0.864, p = 0.003) and sarcopenia in the general population after adjusting for age, sex, body mass index (BMI), daily activity levels, hypertension, heart disease and cardiac drugs. In addition, in multivariate linear regression, lnSDNN (β = 0.146, p = 0.001), lnCVRR (β = 0.120, p = 0.010), lnLF (β = 0.066, p = 0.002) and lnHF (β = 0.065, p < 0.001) remained significantly positively associated with muscle mass, but there were no significant differences in grip strength and walking speed.

CONCLUSION

Sarcopenia was independently associated with lower heart rate variability in a community-dwelling elderly Chinese population. In addition, muscle mass was positively associated with heart rate variability in the elderly.

Investigating the association of anxiety disorders with heart rate variability measured using a wearable device

BACKGROUND

Reduced vagally-mediated heart rate variability (HRV) has been associated with anxiety disorders (AD). The aim of this study was to use a wearable device and remote study design to re-evaluate the association of HRV with ADs, anxiety-related traits, and confounders.

METHODS

240 individuals (AD = 120, healthy controls = 120) completed an at-home assessment of their short-term resting vagally-mediated HRV using a wristband, monitored over videoconference. Following quality control, analyses were performed investigating differences in HRV between individuals with AD (n = 119) and healthy controls (n = 116), associations of HRV with anxiety-related traits and confounders, and antidepressants effects on HRV in patients, including analyses stratified by ancestry (i.e., European, East Asian, African).

RESULTS

Among the confounders investigated, only age had a significant association with HRV. Patients with an AD had significantly lower vagally-mediated HRV than healthy controls in the European subsample, with a trend of significance in the whole sample. HRV was significantly associated with the Hamilton Anxiety Rating Scale (HAM-A) but not with antidepressant use in the European subsample.

LIMITATIONS

The study measures occurred in a non-standardized at-home setting, and the three ancestry group sample sizes were unequal.

CONCLUSIONS

This study demonstrates reduced vagally-mediated HRV among patients with ADs compared to healthy controls. Results also point to low HRV being related to more physical anxiety symptoms (measured via HAM-A), suggesting a possible anxiety subtype. Overall, this study highlights the feasibility of using wearables for patients and encourages exploration of the biological and clinical utility of HRV as a risk factor for ADs.

The effects of acute exercise and a nap on heart rate variability and memory in young sedentary adults

Recent evidence suggests that the autonomic nervous system can contribute to memory consolidation during sleep. Whether fluctuations in cardiac autonomic activity during sleep following physical exercise contribute to the process of memory consolidation has not been studied. We assessed the effects of a non-rapid eye movement (NREM) nap following acute exercise on cardiac autonomic regulation assessed with heart rate variability (HRV) to examine if HRV influences memory processes. Fifty-six (59% female) healthy young adults (23.14 ± 3.74 years) were randomly allocated to either the exercise plus nap (ExNap, n = 27) or nap alone (NoExNap, n = 29) groups. The ExNap group performed a 40-minute moderate-intensity cycling, while the NoExNap group was sedentary prior to learning 45 neutral pictures for a later test. Subsequently, participants underwent a 60-minute NREM nap while measuring EKG, followed by a visual recognition test. Our results indicated that heart rate did not significantly differ between the groups (p = .243), whereas vagally mediated HRV indices were lower in the ExNap group compared to the NoExNap group (p < .05). There were no significant differences in sleep variables between the groups (p > .05). Recognition accuracy was significantly higher in the ExNap group than in the NoExNap group (p = .027). In addition, the recognition accuracy of the ExNap group was negatively associated with vagally mediated HRV (p < .05). Pre-nap acute exercise appears to attenuate parasympathetic activity and to alter the relationship between memory and cardiac autonomic activity.

Racial Differences in Blood Pressure and Autonomic Recovery Following Acute Supramaximal Exercise in Women

Despite the growing popularity of high-intensity anaerobic exercise, little is known about the acute effects of this form of exercise on cardiovascular hemodynamics or autonomic modulation, which might provide insight into the individual assessment of responses to training load. The purpose of this study was to compare blood pressure and autonomic recovery following repeated bouts of acute supramaximal exercise in Black and White women. A convenience sample of twelve White and eight Black young, healthy women were recruited for this study and completed two consecutive bouts of supramaximal exercise on the cycle ergometer with 30 min of recovery in between. Brachial and central aortic blood pressures were assessed by tonometry (SphygmoCor Xcel) at rest and 15-min and 30-min following each exercise bout. Central aortic blood pressure was estimated using brachial pressure waveforms and customized software. Autonomic modulation was measured in a subset of ten participants by heart-rate variability and baroreflex sensitivity. Brachial mean arterial pressure and diastolic blood pressure were significantly higher in Blacks compared to Whites across time (race effect, p = 0.043 and p = 0.049, respectively). Very-low-frequency and low-frequency bands of heart rate variability, which are associated with sympathovagal balance and vasomotor tone, were 22.5% and 24.9% lower, respectively, in Blacks compared to Whites (race effect, p = 0.045 and p = 0.006, respectively). In conclusion, the preliminary findings of racial differences in blood pressure and autonomic recovery following supramaximal exercise warrant further investigations of tailored exercise prescriptions for Blacks and Whites.

Determinants of awake oropharyngeal volume reduction between sitting and supine positions in children evaluated for snoring

Pharyngeal collapsibility is a major determinant of obstructive sleep apnea (OSA) pathophysiology, but its anatomical predictors in children are largely unknown. We hypothesised that anatomical (tonsillar hypertrophy, narrow palate, nasal obstruction, dental/skeletal malocclusion, obesity) and OSA-related (apnea-hypopnea index, AHI) parameters could be related to a measure of awake pharyngeal collapsibility. We performed acoustic pharyngometry in children evaluated for suspected OSA, allowing us to measure the reduction of oropharyngeal volume in supine versus sitting position normalised for the volume in supine position (ΔV%), a measure of pharyngeal collapsibility. In addition to polysomnography and a clinical examination (anatomical parameters), acoustic rhinometry was used to assess nasal obstruction. A total of 188 snoring children were included, 118 (63%) of whom were obese and 74 (39%) of whom had moderate to severe OSA (AHI ≥5/h). The median (25th-75th percentiles) ΔV% in the whole population was 20.1% (4.7; 43.3). ΔV% was independently and positively associated with AHI (p = 0.023), z-score of BMI (p = 0.001), tonsillar hypertrophy (p = 0.007), narrow palate (p = 0.035), and African (p < 0.001) ancestry. By contrast, ΔV% was not modified by dental or skeletal malocclusion, Friedman palate position class or nasopharyngeal obstruction. Tonsillar hypertrophy, obesity, narrow palate and African ancestry are independently associated with an increase in pharyngeal collapsibility in snoring children, thus increasing the risk of OSA. Increased pharyngeal compliance in African children may explain the increased risk of residual OSA after adenotonsillectomy observed in this population.

Heart rate variability as a marker of autonomic nervous system activity in young people with eosinophilic and non-eosinophilic asthma

OBJECTIVE

An imbalance in autonomic nervous system (ANS) activity may play a role in asthma, but it is unclear whether this is associated with specific pathophysiology. This study assessed ANS activity by measuring heart rate variability (HRV) in eosinophilic (EA) and non-eosinophilic asthma (NEA) and people without asthma.

METHODS

HRV, combined hypertonic saline challenge/sputum induction, exhaled nitric oxide (FeNO), skin prick tests to measure atopy, and spirometry tests were conducted in teenagers and young adults (14-21 years) with (n = 96) and without (n = 72) generally well-controlled asthma. HRV parameters associated with sympathetic and parasympathetic ANS branches were analyzed. EA and NEA were defined using a 2.5% sputum eosinophil cut-point. Airway hyperreactivity (AHR) was defined as ≥15% reduction in FEV₁ following saline challenge.

RESULTS

HRV parameters did not differ between asthmatics and non-asthmatics or EA and NEA. They were also not associated with markers of inflammation, lung function or atopy. However, increased absolute low frequency (LFµs²; representing increased sympathetic nervous system (SNS) activity) was found in asthmatics who used β-agonist medication compared to those who did not (median: 1611, IQR 892-3036 vs 754, 565-1592; p < 0.05) and increased normalized low frequency (LF nu) was found in those with AHR compared to without AHR (64, 48-71 vs 53, 43-66; p < 0.05).

CONCLUSION

ANS activity (as measured using HRV analysis) is not associated with pathophysiology or inflammatory phenotype in young asthmatics with generally well-controlled asthma. However, enhanced SNS activity can be detected in asthmatics with AHR or who use β-agonist medication.

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

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

Continuous ECG monitoring should be the heart of bedside AI-based predictive analytics monitoring for early detection of clinical deterioration

The idea that we can detect subacute potentially catastrophic illness earlier by using statistical models trained on clinical data is now well-established. We review evidence that supports the role of continuous cardiorespiratory monitoring in these predictive analytics monitoring tools. In particular, we review how continuous ECG monitoring reflects the patient and not the clinician, is less likely to be biased, is unaffected by changes in practice patterns, captures signatures of illnesses that are interpretable by clinicians, and is an underappreciated and underutilized source of detailed information for new mathematical methods to reveal.

Resting Heart Rate Variability, Perceived Emotion Regulation, and Low-Risk Drug Use in College-Aged Adults: Gender as a Moderator

Identification of individual differences in drug use is warranted, as a history of use is associated with future drug problems. Such drug use is thought to disrupt inhibitory and motivation networks involved in emotion regulation (ER). Higher resting heart rate variability (HRV), a biomarker of effective inhibitory abilities, is associated with less substance (e.g., alcohol, opioid) use. Higher HRV is associated with lower perceived ER difficulties, and this link is stronger in women relative to men. Evidence suggests women might engage in drug use primarily to reduce stress, and men primarily to induce feelings of elation. Research has yet to examine associations among individuals' difficulties in ER, resting HRV, and a recent history of drug use; the current study explored this, in addition to how these associations might differ as a function of gender. Young and healthy college students (N = 190; 88 women) completed a 5-min baseline to assess resting HRV, followed by the 36-item difficulties in ER Scale and 10-item Drug Abuse Screening Test. Higher difficulties in ER, but not resting HRV, were associated with a greater history of "low-risk" drug use in the full sample and moderation tests confirm this link was stronger in women. Moderated-mediation results confirmed an indirect association between resting HRV and drug use, mediated by self-reported difficulties among women only. A significant association between resting HRV and Difficulties in Emotion Regulation Scale (DERS) emerged only among women without a history of drug use. These results indicate that difficulties in ER are both associated with a low-risk history of drug use and underlie an indirect link between resting HRV and drug use history in women only. Among these women with a history of drug use relative to women without, there was no link between resting HRV and self-reported difficulties in ER, suggesting a disrupted inhibitory-motivational pathway. Additional work is needed to understand the psychophysiological correlates of a history of low-risk drug use in young men. These data are in line with research suggesting gender differences in the motivation to engage in recreational drug use and ER interventions might be important in women who engage in low-risk recreational drug use.

Heart Rate Variability Reflects Similar Cardiac Autonomic Function in Explosive and Aerobically Trained Athletes

Autonomic cardiac function can be indirectly detected non-invasively by measuring the variation in microtiming of heart beats by a method known as heart rate variability (HRV). Aerobic training for sport is associated with reduced risk for some factors associated with cardiovascular diseases (CVD), but effects on autonomic function in different athlete types are less known. To compare cardiac autonomic modulation using a standard protocol and established CVD risk factors in highly trained intercollegiate athletes competing in aerobic, explosive, and cross-trained sports. A total of 176 college athletes were categorized in distinct sports as explosive (EA), aerobic (AA), or cross-trained (mixed) athletes. Eight different HRV measures obtained at rest were compared across training type and five health factors: systolic (SBP), diastolic blood pressure (DBP), body weight (BW), sex, and race. All athletic types shared favorable HRV measures that correlated with low CVD risk factors and indicated normal sympathovagal balance. A significant correlation was reported between DBP and pNN50 (% RR intervals > 50 ms) (β = -0.214, p = 0.011) and between BW and low-frequency (LF) power (β = 0.205, p = 0.006). Caucasian and African American athletes differed significantly (p < 0.05) with respect to four HRV variables: pNN50, HF power, LF power, and LF/HF ratios. Explosive, aerobic and mixed athletes had similar cardiovascular and autonomic HRV results in all eight HRV parameters measured. All athletes reported LF and pNN50 values that were significantly correlated with two CVD risk factors: DBP and BW. Compared with Caucasian teammates, African American athletes demonstrated lower LF/HF and higher pNN50, indicating an even more favorable resting sympathovagal activity and healthy CV function.

The Different Facets of Heart Rate Variability in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), a heterogeneous and multifactorial sleep related breathing disorder with high prevalence, is a recognized risk factor for cardiovascular morbidity and mortality. Autonomic dysfunction leads to adverse cardiovascular outcomes in diverse pathways. Heart rate is a complex physiological process involving neurovisceral networks and relative regulatory mechanisms such as thermoregulation, renin-angiotensin-aldosterone mechanisms, and metabolic mechanisms. Heart rate variability (HRV) is considered as a reliable and non-invasive measure of autonomic modulation response and adaptation to endogenous and exogenous stimuli. HRV measures may add a new dimension to help understand the interplay between cardiac and nervous system involvement in OSA. The aim of this review is to introduce the various applications of HRV in different aspects of OSA to examine the impaired neuro-cardiac modulation. More specifically, the topics covered include: HRV time windows, sleep staging, arousal, sleepiness, hypoxia, mental illness, and mortality and morbidity. All of these aspects show pathways in the clinical implementation of HRV to screen, diagnose, classify, and predict patients as a reasonable and more convenient alternative to current measures.

Further Exploration of Treatment Response in Latinos with Comorbid Asthma and Panic Disorder: A Brief Report of HRV and ETCO2 as Potential Mediators of Treatment Response

Heart rate variability (HRV) and end tidal CO2 (ETCO2) in relation to treatment response have not been studied in Latino populations or in comorbid asthma and panic disorder (PD). An extension of previously published research, the current study explored psychophysiological variables as possible mediators of treatment response. Latino treatment completers (N = 32) in the Bronx with asthma-PD received either Cognitive-Behavioral Psychophysiological Therapy (CBPT) or Music Relaxation Therapy (MRT). CBPT included HRV-biofeedback (HRVB); in-the-moment heart rate data to help an individual learn to influence his/her own heart rate. The sample was primarily female (93.8%) and Puerto Rican (81.25%). Treatment groups did not differ on demographics, except for less education in CBPT. The Panic Disorder Severity Scale (PDSS) and Asthma Control Questionnaire (ACQ) assessed changes in symptoms. HRV and ETCO2 were measured at four of eight therapy sessions. Baseline ETCO2 and changes in HRV from first to last of psychophysiology sessions were investigated as mediators of change on ACQ and PDSS. Mixed model analyses indicated in the CPBT group, changes in both asthma control and PD severity were not mediated by changes in HRV. In the CBPT and MRT groups combined, changes in PD severity were not mediated by baseline ETCO2. These findings may be due to the brevity of HRVB in CBPT, multiple treatment components, ETCO2 not directly targeted, and/or unique physiological pathways in Latinos with asthma-PD.

Exploring autonomic regulation in children with ADHD with and without comorbid anxiety disorder through three systematic levels of cardiac vagal control analysis: Rest, reactivity, and recovery

Autonomic nervous system (ANS) dysregulation, characterized by reduced vagally mediated Heart Rate Variability (HRV), has been associated with Attention-Deficit/ Hyperactivity Disorder (ADHD). This study investigated the dynamic vagal modulation of cardiac output in response to shifts in environmental demands in children and adolescents with ADHD, with and without a comorbid anxiety disorder. High-frequency HRV (HF-HRV) measures were obtained from 46 children and adolescents ranging from 6 to 17 (M = 9.38; SD = 2.31) years old, during three successive experimental conditions: a baseline recording followed by a sustained attention task, and a post-task recovery period. Findings support the reliability of the d2 Test, a cancelation test of attention and concentration, to induce parasympathetic withdrawal and extend prior work on "vagal flexibility". Further, these findings suggest a pattern of group differences in ANS functioning in children with ADHD, with and without a comorbid anxiety disorder. Only the ADHD without comorbid anxiety group showed a normative autonomic response to the cognitive challenge (reduced HF-HRV). The participants did not display an adaptive process of restoration following the cognitive challenge; the HRV suppression was prolonged during post-task recovery period, suggesting that ANS responded as if the cognitive stressor was still present. The current paper covers and discusses theoretical implications for the abnormalities in neurophysiological functioning and the different physiological responses in the two ADHD subtypes.

Exploring the Association between Sleep Quality and Heart Rate Variability among Female Nurses

The quality of nurses' work has a direct effect on patient health, and poor sleep has been positively associated with nurses' medical errors. The aim of this study was to investigate the relationship between quality of sleep and heart rate variability (HRV) among female nurses. A descriptive cross-sectional correlational study design was used in January 2014 to study female nurses (n = 393) employed in a medical center in Taiwan. Data were obtained from several questionnaires. HRV was analyzed with five-minute recordings of heart rate signals obtained using a Heart Rater SA-3000P. Approximately 96% of the participants self-reported a poor quality of sleep. Compared to non-shift nurses, significant decreases were found in total power (TP) and low-frequency HRV among shift-work nurses. However, negative correlations were found between sleep quality and HRV, including total power, low frequency, and the low frequency/high frequency ratio (r = -0.425, p < 0.05; r = -0.269, -0.266, p < 0.05). In a stepwise multiple regression analysis, 23.1% of variance in quality of sleep can be explained by TP and heart rate. The sleep quality of female nurses was poor and this affected their autonomic nervous system, which can contribute unfavorable consequences for their health.

A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices of heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) and pre-ejection period (PEP; a systolic time interval and measure of sympathetic activity). However, HF-HRV and PEP are considered measures of chronotropic and inotropic cardiac influence, respectively. Left ventricular ejection time (LVET) is a systolic time interval that reflects sympathetic chronotropic influence, and therefore may be a more appropriate measure for calculating CAB and CAR compared to PEP. Thus, the current study evaluates both PEP and LVET in the calculation of CAB and CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD = 1.84 years) were available for analyses. CAB and CAR values were calculated using both HF-HRV and the root mean square of successive differences, in addition to both PEP and LVET, in accordance with previously established guidelines. Analyses showed that correlations were significantly weaker between CAB and CAR calculated using LVET for both HF (z = 5.12, p < 0.001) and RMSSD (z = 5.26, p < 0.001) than with PEP. These data suggest that LVET, compared to PEP, provides better “autonomic space” as evidenced by a lack of correlation between CAB and CAR computed using LVET. We stress that future research consider calculating CAB and CAR using chronotropic measures for both parasympathetic and sympathetic activity, as doing so may yield more accurate and independent measures of cardiac autonomic activity compared to a mixture of inotropic (i.e., PEP) and chronotropic (i.e., HF-HRV) measures.

Resting state heart rate variability and false memories

Recent studies have shown higher resting-state vagally-mediated heart rate variability (vmHRV) to be related to greater memory retrieval. Research has not yet linked resting vmHRV with memory encoding and retrieval, as both are thought to play an important role in correctly distinguishing between true and false memories. The current study investigated this possible link in n = 71 undergraduate students. VmHRV was assessed during a 5-minute resting baseline period. Participants then completed the Deese-Roediger-McDermott (DRM) task, where they first viewed 6 word lists (12 words per list), and were later asked to identify previously shown words (true memories) and reject non-presented words. Results showed that participants with lower resting vmHRV were less able to discriminate true from false items. These data extend previous work on resting vmHRV and memory suggesting that resting vmHRV represents a psychophysiological pathway involved in both the proper encoding and retrieval of memories.

Race and sex differences in cardiovascular autonomic regulation

Racial and ethnic differences in cardiovascular morbidity and mortality persist despite advances in risk factor identification and implementation of evidence-based treatment strategies. African American men and women are disproportionately affected by cardiovascular risk factors, particularly hypertension. In this context, previous studies have identified sex and racial differences in autonomic cardiovascular regulation which may contribute to the development of hypertension and its high morbidity burden among African Americans. In this review, we provide a comprehensive evaluation of the potential pathophysiological mechanisms of blood pressure control and their differences based on sex and race. These mechanisms include obesity-induced sympathetic activation, sympatho-vascular transduction, baroreflex sensitivity and adrenoreceptor vascular sensitivity, which have been the subjects of prior investigation in this field. Understanding the racial differences in the pathophysiology of hypertension and its co-morbid conditions would allow us to implement better treatment strategies tailored to African Americans, with the ultimate goal of reducing cardiovascular mortality in this population.

Neural control of cardiovascular function in black adults: implications for racial differences in autonomic regulation

Black adults are at increased risk for developing hypertension and cardiovascular and chronic kidney disease and have greater associated morbidity/mortality than white adults who are otherwise demographically similar. Despite the key role of the autonomic nervous system in the regulation of cardiovascular function, the mechanistic contributions of sympathetic nerves to racial differences in cardiovascular dysfunction and disease remain poorly understood. In this review, we present an update and synthesis of current understanding regarding the roles of autonomic neural mechanisms in normal and pathophysiological cardiovascular control in black and white adults. At rest, many hemodynamic and autonomic variables, including blood pressure, cardiac output, and sympathetic nerve activity, are similar in healthy black and white adults. However, resting sympathetic vascular transduction and carotid baroreflex responses are altered in ways that tend to promote increased vasoconstriction and higher blood pressure, even in healthy, normotensive black adults. Acute sympathoexcitatory maneuvers, including exercise and cold pressor test, often result in augmented sympathetic and hemodynamic responses in healthy black adults. Clinically, although mechanistic evidence is scarce in this area, existing data support the idea that excessive sympathetic activation and/or transduction into peripheral vasoconstriction contribute importantly to the pathophysiology of hypertension and chronic kidney disease in black compared with white adults. Important areas for future work include more detailed study of sympathetic and hemodynamic reactivity to exercise and other stressors in male and female black adults and, particularly, sympathetic control of renal function, an important area of clinical concern in black patients.

Stereotype threat, trait perseveration, and vagal activity: evidence for mechanisms underpinning health disparities in Black Americans

Objective: Black Americans (BAs) are at an elevated risk for morbidity and mortality in comparison to White Americans (WAs). Racial stressors are a common occurrence in American culture and is theorized to contribute to these disparities. When race-focused, stereotype threat (ST) is considered to be a factor that is detrimental to health in BAs; however few studies have directly investigated the impact of a ST manipulation on physiological function. Furthermore, it is proposed that racial stressors such as ST may have prolonged effects when more likely to perseverate (e.g. rumination) over the stressor and thus, those with greater trait perseveration may be more affected by ST. We sought to explore the impact of ST and trait perseveration on changes in vagus nerve activity - an indication of adaptive psychological and physiological well-being - as indexed by vagally mediated heart rate variability (vmHRV). Design: Forty-three (24 females, mean age of 20, standard deviation of 3 years) apparently healthy BA individuals were randomly assigned to one of three experimental conditions in which they received either implicit (subtle), explicit (blatant), or no ST priming (control condition), prior to completing a cognitive task. Resting vmHRV was assessed both at baseline (pre-task) and recovery (post-task). Results: BAs in the explicit ST condition exhibited the greatest decrease in vmHRV in comparison to the control group from pre- to post-task. BAs with moderate to high levels of trait perseveration showed the greatest decrease in vmHRV from pre- to post-task in comparison to those with lower levels of trait perseveration and BAs in the control group. Conclusion: These data suggest that racial ST, especially when explicit and coupled with trait perseveration, can decrease vagal activity, as indexed by decreased vmHRV, which when experienced frequently can have significant consequences for health and longevity in BAs.

The Autonomic Nervous System and Hypertension: Ethnic Differences and Psychosocial Factors

PURPOSE OF THE REVIEW

In the present paper, we overview emerging research examining the autonomic nervous system (ANS), especially the parasympathetic nervous system as indexed by heart rate variability (HRV), and the impact of psychosocial factors on hypertension-related disease in African Americans.

RECENT FINDINGS

A growing corpus of studies has shown that (1) usual patterns of compensatory sympathetic-parasympathetic regulation differ between African Americans and European Americans; (2) despite their enhanced cardiovascular disease risk profile, African Americans tend to exhibit higher HRV relative to European Americans; and (3) racial discrimination and other forms of psychosocial stress are associated with diminished HRV among African Americans. Significant disparities in hypertension-related disease exist such that African Americans have greater risk. The underlying factors associated with this increased risk are, to date, not fully understood. The present review provides evidence for a unique pattern of ANS regulation in African Americans and shows that psychosocial factors such as racial discrimination may contribute to this paradoxical situation.

The effects of crossing ethnic boundaries on the autonomic nervous system in Muslim and Jewish young women in Israel

Exposure to alien inter-group environments can differently effect ethnic groups’ autonomous nervous system, measured by heart rate variability (HRV). Our aim was to evaluate the effect of crossing alien ethnic boundaries on heart rate variability in three selected types of environments. In a field experiment study, we test responses of 72 Muslim and Jewish women to exposure to alien ethnic environments. We measured their HRV in intra and inter-ethnic parks, town centers and residential neighborhoods in Arab and Jewish adjacent towns. The subjects stayed half an hour in each environment. Mixed models were used to evaluate the effects. The results show that for both groups more favorable HRV measurements were demonstrated in intra-ethnic environments as compared to their HRV once crossing ethnic boundaries. The strongest effect in frequency domain (LF/HF) in response to ethnic boundary crossing was observed in the park for Muslims (β:0.65, 95%CI: 0.60–0.70) and for Jews (β: 0.60, 95%CI: 0.57–0.63). Following the eruption of the uprising, the most significant increase in LF/HF in response to ethnic boundary crossing was demonstrated in parks (β: 0.66, 95%CI: 0.60–0.71). In conclusion, both groups are effected by boundary crossing but there are ethnic differences in the autonomic nervous system balance and in response to crossing alien ethnic boundaries. A further study is needed to understand the causes of these differences.

Body mass index and parasympathetic nervous system reactivity and recovery following graded exercise

OBJECTIVES

The present study sought to expand upon prior investigations examining patterns of vagally mediated heart rate variability (vmHRV) and perceived exertion as a function of body mass index (BMI) in response to and recovery from exercise.

METHODS

Participants underwent a resting (baseline) period, followed by a graded exercise protocol on an ergometer with ascending difficulty stages, and finally another resting (recovery) period. Individuals were stratified into three BMI groups: low, moderate, and high.

RESULTS

Individuals in the high BMI group exhibited a significantly greater decrease in vmHRV from baseline to graded exercise in comparison to the moderate BMI group. Individuals in the high BMI group also showed significantly lower vmHRV at recovery compared with baseline than individuals with moderate BMI; indicating that the high BMI group's vmHRV did not recover to the degree of those in the moderate BMI group. No significant results regarding vmHRV were found in the low BMI group. Of note, BMI and perceived exertion during the recovery period were positively associated. Results also showed a significant negative association between vmHRV and perceived exertion at each grade of exercise. There was no significant association between vmHRV and perceived exertion during baseline or recovery.

CONCLUSIONS

This report extends prior research studying BMI and patterns of vmHRV reactivity in the domain of physical exercise. Our data contribute to previous reports suggesting that high BMI can lead to maladaptive patterns of vmHRV reactivity to and recovery from physical exercise.

Influence of Heart Rate, Age, and Gender on Heart Rate Variability in Adolescents and Young Adults

Key autonomic functions are in continuous development during adolescence which can be assessed using the heart rate variability (HRV). However, the influence of different demographic and physiological factors on HRV indices has not been fully explored in adolescents. In this study we aimed to assess the effect of age, gender, and heart rate on HRV indices in two age groups of healthy adolescents (age ranges, 13-16 and 17-20 years) and two groups of healthy young adults (21-24 and 25-30 years). We addressed the issue using 5-min ECG recordings performed in the sitting position in 255 male and female participants. Time, frequency, and informational domains of HRV were calculated. Changes in HRV indices were assessed using a multiple linear regression model to adjust for the effects of heart rate, age, and gender. We found that heart rate produced more significant effects on HRV indices than age or gender. There was a progressive reduction in HRV with increasing age. Sympathetic influence increased with age and parasympathetic influence progressively decreased with age. The influence of gender was manifest only in younger adolescents and young adults. In conclusion, age, gender, and particularly heart rate have a substantial influence on HRV indices, which ought to be considered to avoid biases in the study of the autonomic nervous system development. The lack of the gender-related effects on HRV indices in late adolescence could be related to non-completely achieved maturity of the autonomic mechanisms, which deserves further exploration.

Resting Heart Rate Variability, Facets of Rumination and Trait Anxiety: Implications for the Perseverative Cognition Hypothesis

The perseverative cognition hypothesis (PCH) posits that perseveration, defined as the repetitive or sustained activation of cognitive representations of a real or imagined stressor, is a primary mechanism linking psychological (or stress) vulnerability with poor health and disease. Resting vagally mediated heart rate variability (vmHRV) is an important indicator of self-regulatory abilities, stress vulnerability and overall health. Those with lower resting vmHRV are more vulnerable to stress, and thus more likely to engage in perseverative cognition and experience subsequent negative mental health outcomes such as anxiety. Recent research suggests that rumination—one of the core mechanisms underlying perseveration—is a construct containing (at least) two maladaptive (depressive and brooding) and one adaptive (reflective) types of rumination. However, to date, research has not examined how the association between resting vmHRV may differ between these three facets of rumination, in addition to these facets’ mechanistic role in linking lower resting vmHRV with greater trait anxiety. The current cross-sectional study explores these relationships in a sample of 203 participants (112 females, 76 ethnic minorities, mean age = 19.43, standard deviation = 1.87). Resting vmHRV was assessed during a 5-min-resting period using an Electrocardiogram (ECG). Both trait rumination (including the three facets) and anxiety were assessed via self-report scales. Significant negative associations were found between resting vmHRV and maladaptive, but not adaptive, forms of perseveration. Similarly, mediation analyses showed a significant indirect relationship between resting vmHRV and anxiety through maladaptive, but not adaptive, facets of rumination. Our findings support the PCH such that those with stress vulnerability, as indexed by lower resting vmHRV, are more likely to engage in maladaptive perseverative cognition and thus experience negative outcomes such as anxiety. Our data also lend a novel outlook on the PCH; resting vmHRV is not related to reflective rumination and thus, this facet of perseveration may be a neutral, but not beneficial, factor in the link between stress vulnerability and psychological well-being.

Hidden Signals-The History and Methods of Heart Rate Variability

The understanding of heart rate variability (HRV) has increased parallel with the development of modern physiology. Discovered probably first in 1847 by Ludwig, clinical applications evolved in the second part of the twentieth century. Today HRV is mostly used in cardiology and research settings. In general, HRV can be measured over shorter (e.g., 5-10 min) or longer (12 or 24 h) periods. Since 1996, most measurements and calculations are made according to the standard of the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. As the first step, the series of times between successive R-peaks in the ECG are in milliseconds. It is crucial, however, to identify and remove extrasystoles and artifacts according to standard protocols. The series of QRS distances between successive heartbeats can be analyzed with simple or more sophisticated algorithms, beginning with standard deviation (SDNN) or by the square root of the mean of the sum of squares of differences between adjacent normal RR (rMSSD). Short-term HRV is frequently analyzed with the help of a non-parametric fast Fourier transformation quantifying the different frequency bands during the measurement period. In the last decades, various non-linear algorithms have been presented, such as different entropy and fractal measures or wavelet analysis. Although most of them have a strong theoretical foundation, their clinical relevance is still debated.

Racial differences in the association between heart rate variability and left ventricular mass

NEW FINDINGS

What is the central question of this study? Decreased heart rate variability (HRV) is associated with increased cardiovascular disease (CVD) risk, including greater left ventricular mass (LVM). Despite their enhanced CVD risk profile, African Americans have been shown to exhibit higher HRV, relative to Whites; however, it is unclear whether this pattern extends to the association between HRV and LVM. What is the main finding and its importance? Using ECG and echocardiographic data, HRV was positively associated with LVM in a non-clinical sample of African Americans. These findings suggest that current assumptions regarding the meaning of higher HRV might not be universal, which might have implications for HRV as a risk marker among African Americans. Increased left ventricular mass (LVM) is an early precursor of target organ damage attributable to hypertension. Diminished parasympathetic cardiac control has been linked to both hypertension onset and left ventricular impairment; however, emerging evidence suggests that this pattern might be different in African Americans. The present study sought to determine whether race impacts the relationship between parasympathetic cardiac control and LVM. The LVM was assessed via echocardiography in a sample (n = 148) of African American and White adults (mean age 33.20 ± 5.71 years) with normal or mildly elevated blood pressure. Parasympathetic cardiac control was assessed by a measure of high-frequency heart rate variability (HF-HRV) determined from ECG recordings during 5 min of rest. In regression analysis, greater HF-HRV was associated with greater LVM among African Americans (P = 0.002) but was not related to LVM in Whites (P = 0.919). These are the first data to demonstrate that race moderates the relationship between HRV and LVM and further suggest that race might be an important factor in the association between parasympathetic cardiac control and other cardiovascular disease risk factors.

Ayurgenomics for stratified medicine: TRISUTRA consortium initiative across ethnically and geographically diverse Indian populations

BACKGROUND

Genetic differences in the target proteins, metabolizing enzymes and transporters that contribute to inter-individual differences in drug response are not integrated in contemporary drug development programs. Ayurveda, that has propelled many drug discovery programs albeit for the search of new chemical entities incorporates inter-individual variability "Prakriti" in development and administration of drug in an individualized manner. Prakriti of an individual largely determines responsiveness to external environment including drugs as well as susceptibility to diseases. Prakriti has also been shown to have molecular and genomic correlates. We highlight how integration of Prakriti concepts can augment the efficiency of drug discovery and development programs through a unique initiative of Ayurgenomics TRISUTRA consortium.

METHODS

Five aspects that have been carried out are (1) analysis of variability in FDA approved pharmacogenomics genes/SNPs in exomes of 72 healthy individuals including predominant Prakriti types and matched controls from a North Indian Indo-European cohort (2) establishment of a consortium network and development of five genetically homogeneous cohorts from diverse ethnic and geo-climatic background (3) identification of parameters and development of uniform standard protocols for objective assessment of Prakriti types (4) development of protocols for Prakriti evaluation and its application in more than 7500 individuals in the five cohorts (5) Development of data and sample repository and integrative omics pipelines for identification of genomic correlates.

RESULTS

Highlight of the study are (1) Exome sequencing revealed significant differences between Prakriti types in 28 SNPs of 11 FDA approved genes of pharmacogenomics relevance viz. CYP2C19, CYP2B6, ESR1, F2, PGR, HLA-B, HLA-DQA1, HLA-DRB1, LDLR, CFTR, CPS1. These variations are polymorphic in diverse Indian and world populations included in 1000 genomes project. (2) Based on the phenotypic attributes of Prakriti we identified anthropometry for anatomical features, biophysical parameters for skin types, HRV for autonomic function tests, spirometry for vital capacity and gustometry for taste thresholds as objective parameters. (3) Comparison of Prakriti phenotypes across different ethnic, age and gender groups led to identification of invariant features as well as some that require weighted considerations across the cohorts.

CONCLUSION

Considering the molecular and genomics differences underlying Prakriti and relevance in disease pharmacogenomics studies, this novel integrative platform would help in identification of differently susceptible and drug responsive population. Additionally, integrated analysis of phenomic and genomic variations would not only allow identification of clinical and genomic markers of Prakriti for application in personalized medicine but also its integration in drug discovery and development programs.

Effects of Body Mass Index on Parasympathetic Nervous System Reactivity and Recovery Following Orthostatic Stress

Vagally mediated heart rate variability (vmHRV), defined as the beat-to-beat fluctuations in a heart series mediated by the vagus nerve, serves as a non-invasive index of parasympathetic nervous system (PNS) activity. Lower resting state vmHRV is associated with greater body mass index (BMI), providing a psychophysiological pathway linking obesity with health and disease. However little research has been conducted to examine how BMI may influence PNS reactivity to orthostatic stress. The present study sought to explore this in a sample of 59 individuals (44 females, mean age = 24.37 years, age range 19-65 years). VmHRV was measured throughout the 5-minute baseline (sitting), orthostatic (standing), and recovery (sitting) conditions. Individuals were stratified into low (BMI < 20), moderate (BMI 20-25), and high (BMI > 25) BMI groups. Results indicate that the high BMI group had a greater decrease in vmHRV from baseline to standing in comparison to the moderate BMI group. Furthermore, the low BMI group showed lower vmHRV during recovery compared to baseline, suggesting that these individuals did not fully recover from the standing position. Taken together, these results extend previous literature showing that those with low and high BMI can show different yet maladaptive patterns of vmHRV in response to orthostatic stress.

Examining the association between perceived discrimination and heart rate variability in African Americans

OBJECTIVE

Previous research attempting to delineate the role of discrimination in racial/ethnic disparities in hypertension has focused largely on blood pressure, which is chiefly governed by the sympathetic branch of the autonomic nervous system. Consequently, few studies have considered the role of the parasympathetic branch and particularly its regulation of the heart via the vagus nerve.

METHOD

In the present cross-sectional study, we employed hierarchical linear regressions to examine associations between perceived ethnic discrimination and resting heart rate variability (HRV), an important biomarker of parasympathetic cardiac modulation and overall health, in a sample (N = 103) of young, healthy African American participants (58% female, M_age = 19.94 years, SD = 2.84).

RESULTS

After accounting for demographic factors and health status characteristics, lifetime discrimination emerged as an inverse predictor of HRV. When subdomains of discrimination were considered, discrimination attributable to threats or actual acts of aggression was also predictive of lower HRV.

CONCLUSIONS

Our findings suggest that a greater lifetime burden of discrimination and discriminatory harassment and/or assault is associated with lower resting HRV in African Americans. The implications of these findings are discussed in the context of past, present and emerging research emphasizing biological linkages between discrimination and health. (PsycINFO Database Record

Heart Rate Variability (HRV) Analysis: A Methodology for Organizational Neuroscience

Recently, the application of neuroscience methods and findings to the study of organizational phenomena has gained significant interest and converged in the emerging field of organizational neuroscience. Yet, this body of research has principally focused on the brain, often overlooking fuller analysis of the activities of the human nervous system and associated methods available to assess them. In this article, we aim to narrow this gap by reviewing heart rate variability (HRV) analysis, which is that set of methods assessing beat-to-beat changes in the heart rhythm over time, used to draw inference on the outflow of the autonomic nervous system (ANS). In addition to anatomo-physiological and detailed methodological considerations, we discuss related theoretical, ethical, and practical implications. Overall, we argue that this methodology offers the opportunity not only to inform on a wealth of constructs relevant for management inquiries but also to advance the overarching organizational neuroscience research agenda and its ecological validity.

Gender-Related Differences in Heart Rate Variability of Epileptic Patients

Recently, heart rate variability (HRV) analysis has been used as an indicator of epileptic seizures. As women have a lower sudden, unexpected death in epilepsy risk and greater longevity than men, the authors postulated that there are significant gender-related differences in heart rate dynamics of epileptic patients. The authors analyzed HRV during 5-minute segments of continuous electrocardiogram recording of age-matched populations. The middle-aged epileptic patients included males ( n = 12) and females ( n = 12), ranging from 41 to 65 years of age. Relatively high- (0.15 Hz-0.40 Hz) and low-frequency (0.01 Hz-0.15 Hz) components of HRV were computed using spectral analysis. Poincaré parameters of each heart rate time series were considered as nonlinear features. The mean heart rate markedly differed between gender groups including both right- and left-sided seizures. High-frequency heart rate power and the low-frequency/high-frequency ratio increased in the pre-ictal phase of both male and female groups ( p < .01), but men showed more increase especially in right-sided seizures. The standard deviation ratio, SD2/ SD1, of pre-ictal phase was greater in males than females ( p < .01). High-frequency spectral power and parasympathetic activity were higher in the female group with both right- and left-sided seizures. Men showed a sudden increase in sympathetic activity in the pre-ictal phase, which might increase the risk of cardiovascular disease in comparison to women. These complementary findings indicate the need to account for gender, as well as localization in HRV analysis.

Disorder of autonomic nervous system and its vulnerability to external stimulation in functional dyspepsia

To elucidate the role of autonomic nervous system in functional dyspepsia patients, we examined 24-h heart rate variability: the basal levels, responses after lunch, cold pressor and mental arithmetic tests, and the efficacy of an autonomic drug (tofisopam). The high-frequency component (HF: 0.15–0.40 Hz) and the ratio of HF to the low-frequency component (LF: 0.04–0.15 Hz; LF/HF ratio) were used as indicators of parasympathetic and sympathetic autonomic nervous system function. The HF component in the 24-h, daytime, and nighttime was low in 86.7%, 97.8%, and 66.7% of patients (n = 45) and the LF/HF ratio was high in 51.1%, 73.3%, and 26.6% of patients. Gastrointestinal symptom tended to be severe in patients with autonomic nervous system disorder (p = 0.085). The abnormal response in HF component after lunch occurred in 38.2% (13/34) of patients who revealed a greater tendency towards in indigestion score (p = 0.061). Delays in recovery to the basal autonomic nervous system level after stimulus of the cold pressor and the mental arithmetic tests occurred in parts of patients. Tofisopam partially improved autonomic nervous system dysfunction and abdominal pain/indigestion. Imbalanced autonomic nervous system function and vulnerability for recovery from external stimuli were observed in functional dyspepsia patients, which was associated with dyspeptic symptoms.

Genetic, Epigenetic, and Environmental Factors Influencing Neurovisceral Integration of Cardiovascular Modulation: Focus on Multiple Sclerosis

Thought to be an autoimmune inflammatory CNS disease, multiple sclerosis (MS) involves multiple pathologies with heterogeneous clinical presentations. An impaired neurovisceral integration of cardiovascular modulation, indicated by sympathetic and parasympathetic autonomic nervous system (ANS) dysfunction, is among common MS clinical presentations. ANS dysfunction could not only enhance MS inflammatory and neurodegenerative processes, but can also lead to clinical symptoms such as depression, fatigue, sleep disorder, migraine, osteoporosis, and cerebral hemodynamic impairments. Therefore, factors influencing ANS functional activities, in one way or another, will have a significant impact on MS disease course. This review describes the genetic and epigenetic factors, and their interactions with a number of environmental factors contributing to the neurovisceral integration of cardiovascular modulation, with a focus on MS. Future studies should investigate the improvement in cardiovascular ANS function, as a strategy for preventing and minimizing MS-related morbidities, and improving patients' quality of life.

Integrating affective and cognitive correlates of heart rate variability: A structural equation modeling approach

High frequency heart rate variability (HRV) is a measure of neurocardiac communication thought to reflect predominantly parasympathetic cardiac regulation. Low HRV has been associated empirically with clinical and subclinical levels of anxiety and depression and, more recently, high levels of HRV have been associated with better performance on some measures of executive functioning (EF). These findings have offered support for theories proposing HRV as an index measure of a broad, self-regulatory capacity underlying aspects of emotion regulation and executive control. This study sought to test that proposition by using a structural equation modeling approach to examine the relationships of HRV to negative affect (NA) and EF in a large sample of U.S. adults ages 30s-80s. HRV was modeled as a predictor of an NA factor (self-reported trait anxiety and depression symptoms) and an EF factor (performance on three neuropsychological tests tapping facets of executive abilities). Alternative models also were tested to determine the utility of HRV for predicting NA and EF, with and without statistical control of demographic and health-related covariates. In the initial structural model, HRV showed a significant positive relationship to EF and a nonsignificant relationship to NA. In a covariate-adjusted model, HRV's associations with both constructs were nonsignificant. Age emerged as the only significant predictor of NA and EF in the final model, showing inverse relationships to both. Findings may reflect population and methodological differences from prior research; they also suggest refinements to the interpretations of earlier findings and theoretical claims regarding HRV.

Sympathetic Activity Assessed during Exercise Recovery in Young Obese Females

OBJECTIVE

To evaluate differences in sympathetic activity, as assessed by an exercise recovery index (ERI; heart rate/oxygen consumption [VO2] plateau), between black and white obese female adolescents. An additional aim was to determine the association of ERI with insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]), cardiovascular fitness per fat-free mass (VO2 per fat-free mass), systolic blood pressure (SBP), and percent body fat (%FAT) in both black and white obese adolescents.

STUDY DESIGN

Sixty-one females volunteered to participate in this study. HOMA-IR, SBP, and %FAT were assessed during resting conditions in black (n = 49, 13.7 ± 1.6 years, 38.1 ± 6.1 kg/m(2)) and white (n = 12, 13.3 ± 2.2 years, 34.3 ± 4.9 kg/m(2)) obese adolescents. An ERI was calculated during a 5-minute passive recovery period immediately following a graded treadmill exercise test to exhaustion.

RESULTS

The ERI was significantly greater in black compared with white obese adolescent females (29.8 ± 6.4 vs 24.1 ± 3.1 bpm·mLO2(-1)·min(-1), P = .004). Using multiple linear regression modeling, there was a significant independent association between ERI and VO2 per fat-free mass (r = -0.310, P = .027) and %FAT (r = 0.326, P = .020) in black obese adolescents after controlling for HOMA-IR and SBP.

CONCLUSIONS

These results suggest that black obese adolescent females have greater sympathetic activity, as assessed by an ERI, than white obese adolescent females. These findings support the need for weight management efforts aimed at both reducing %FAT and improving fitness in obese adolescents, specifically black females.

TRIAL REGISTRATION

Registered with Clinicaltrials.gov: NCT00562293.

Reliability of ultra-short-term analysis as a surrogate of standard 5-min analysis of heart rate variability

BACKGROUND

Despite the increasing demands of ultra-short-term heart rate (HR) variability (HRV) for practical ambulatory applications, there have been few studies that have investigated R-R interval recording for less than 5 min for HRV analysis. It has not been extensively validated, and, currently, no normative data for ultra-short-term HRV exist. The aim of this study was to investigate the relationship between standard 5-min and ultra-short-term HRV by collecting data from a large population consisting of a wide range of age groups.

MATERIALS AND METHODS

The 5-min R-R interval series were obtained from 467 healthy volunteers ranging from 8 to 69 years of age. The original R-R interval was segmented into 270, 240, 210, 180, 150, 120, 90, 60, 30, 20, and 10 s, and those HRV features most commonly reported within the literature were calculated and compared with those using the original 5-min R-R interval series. The Pearson correlation r, the p value by the Kruskal-Wallis test, and the Bland-Altman plot analysis computations were performed for each HRV variable calculated using different lengths of R-R interval series.

RESULTS

For each HRV variable, the minimum length of the R-R interval required to reliably estimate the 5-min HRV was identified. The results were different for each age group: 10 s for HR, 20 s for high-frequency, 30 s for root mean square difference, 60 s for proportion of the number of interval differences of successive NN intervals greater than 50 ms divided by total number of NNs, 90 s for low-frequency, normalized low-frequency, normalized high-frequency, and low-frequency/high-frequency, 240 s for standard deviation of successive NN interval differences and time-frequency, and 270 s for very low-frequency. In addition, the reference value for short-term HRV from normal healthy subjects was also presented.

CONCLUSIONS

Some HRV variables calculated from R-R interval series shorter than 5 min were well matched with those calculated from the 5-min R-R interval. Thus, ultra-short-term HRV is likely to be a good surrogate method to assess trends in HRV.

Ethnic differences in resting heart rate variability: a systematic review and meta-analysis

BACKGROUND

Ethnic disparities in cardiovascular morbidity and mortality are widely documented in the literature. Recently, research has shown that decreased parasympathetic cardiac modulation is associated with the established and emerging risk factors for cardiovascular disease (CVD) and stroke. In consideration of the disproportionate CVD risk and disease profile of African Americans (AAs), it is plausible that decreased cardiac parasympathetic functioning may partially explain these disparities. In the present systematic review and meta-analysis, we assess the available evidence for a reliable ethnic difference in tonic vagally mediated heart rate variability (HRV), an indicator of parasympathetic cardiac modulation.

METHODS

A systematic literature search was conducted yielding studies comparing tonic HRV in AAs and European Americans. Adjusted standardized effect sizes (Hedges g) were calculated using a mixed-effects model, with restricted maximum likelihood estimation for 17 studies containing appropriate measures of vagally mediated HRV.

RESULTS

Meta-analysis results suggest that AAs have greater HRV than do European Americans (Hedges g = 0.93, 95% confidence interval = 0.25-1.62), even after consideration of several covariates including health status, medication use, and subgroup stratification by sex and age.

CONCLUSIONS

These findings suggest that decreased vagally mediated HRV is not likely to account for the persistent health disparities experienced by AAs with respect to CVD risk and burden. These disparities underscore the need for continued research addressing socioethnic cardiovascular differences and the biobehavioral mechanisms involved.

"More than skin deep": stress neurobiology and mental health consequences of racial discrimination

Ethnic minority groups across the world face a complex set of adverse social and psychological challenges linked to their minority status, often involving racial discrimination. Racial discrimination is increasingly recognized as an important contributing factor to health disparities among non-dominant ethnic minorities. A growing body of literature has recognized these health disparities and has investigated the relationship between racial discrimination and poor health outcomes. Chronically elevated cortisol levels and a dysregulated hypothalamic-pituitary-adrenal (HPA) axis appear to mediate effects of racial discrimination on allostatic load and disease. Racial discrimination seems to converge on the anterior cingulate cortex (ACC) and may impair the function of the prefrontal cortex (PFC), hence showing substantial similarities to chronic social stress. This review provides a summary of recent literature on hormonal and neural effects of racial discrimination and a synthesis of potential neurobiological pathways by which discrimination affects mental health.

Racial differences in heart rate variability during sleep in women: the study of women across the nation sleep study

BACKGROUND

Heart rate variability (HRV) differs markedly by race, yet few studies have evaluated these relationships in women, and none have done so during sleep (sHRV).

METHODS

We addressed these gaps by examining sHRV in women of African American, Chinese American, or European American origin or descent (mean [standard deviation] age = 51.2 [2.2] years).

RESULTS

HRV during Stage 2 non-rapid eye movement (NREM) and rapid eye movement (REM) sleep differed significantly by race after adjusting for possible confounders. Normalized high-frequency HRV was significantly lower in European American compared with African American and Chinese American participants (European American NREM = 0.35 [0.01], REM = 0.23 [0.01]; African American NREM = 0.43 [0.02], REM = 0.29 [0.02]; Chinese American NREM = 0.47 [0.03], REM = 0.33 [0.02]; p values <.001). European Americans also exhibited higher low-to-high-frequency HRV ratios during sleep compared with African American and Chinese American women (European American NREM = 2.42 [1.07], REM = 5.05 [1.07]; African American NREM = 1.69 [1.09], REM = 3.51 [1.09]; Chinese American NREM = 1.35 [1.07], REM = 2.88 [1.13]; p values <.001).

CONCLUSIONS

Race was robustly related to sHRV. Compared with women of African American or Chinese American origin or descent, European American women exhibited decreased vagally mediated control of the heart during sleep. Prospective data are needed to evaluate whether sHRV, including race differences, predicts cardiovascular disease.

Heart rate variability on antihypertensive drugs in black patients living in sub-Saharan Africa

Background

Compared with Caucasians, African Americans have lower heart rate variability (HRV) in the high-frequency domain, but there are no studies in blacks born and living in Africa.

Methods

In the Newer versus Older Antihypertensive agents in African Hypertensive patients trial (NCT01030458), patients (30–69 years) with uncomplicated hypertension (140–179/90–109 mmHg) were randomized to single-pill combinations of bisoprolol/hydrochlorothiazide (R) or amlodipine/valsartan (E). 72 R and 84 E patients underwent 5-min ECG recordings at randomization and 8, 16 and 24 weeks. HRV was determined by fast Fourier transform and autoregressive modelling.

Results

Heart rate decreased by 9.5 beats/min in R patients with no change in E patients (− 2.2 beats/min). R patients had reduced total (− 0.13 ms²; p = 0.0038) and low-frequency power (− 3.6 nu; p = 0.057), higher high-frequency (+ 3.3 nu; p = 0.050) and a reduced low- to high-frequency ratio (− 0.08; p = 0.040). With adjustment for heart rate, these differences disappeared, except for the reduced low-frequency power in the R group (− 4.67 nu; p = 0.02). Analyses confined to 39 R and 47 E patients with HRV measurements at all visits or based on autoregressive modelling were confirmatory.

Conclusion

In native black African patients, antihypertensive drugs modulate HRV, an index of autonomous nervous tone. However, these effects were mediated by changes in heart rate except for low-frequency variability, which was reduced on beta blockade independent of heart rate.

Measured maximal heart rates compared to commonly used age-based prediction equations in the Heritage Family Study

OBJECTIVE

The purpose of this study was to examine how well two commonly used age-based prediction equations for maximal heart rate (HRmax ) estimate the actual HRmax measured in Black and White adults from the HERITAGE Family Study.

METHODS

A total of 762 sedentary subjects (39% Black, 57% Females) from HERITAGE were included. HRmax was measured during maximal exercise tests using cycle ergometers. Age-based HRmax was predicted using the Fox (220-age) and Tanaka (208 - 0.7 × age) formulas.

RESULTS

The standard error of estimate (SEE) of predicted HRmax was 12.4 and 11.4 bpm for the Fox and Tanaka formulas, respectively, indicating a wide-spread of measured-HRmax values are compared to their age-predicted values. The SEE (shown as Fox/Tanaka) was higher in Blacks (14.4/13.1 bpm) and Males (12.6/11.7 bpm) compared to Whites (11.0/10.2 bpm) and Females (12.3/11.2 bpm) for both formulas. The SEE was higher in subjects above the BMI median (12.8/11.9 bpm) and below the fitness median (13.4/12.4 bpm) when compared to those below the BMI median (12.2/11.0 bpm) and above the fitness median (11.4/10.3) for both formulas.

CONCLUSION

Our findings show that based on the SEE, the prevailing age-based estimated HRmax equations do not precisely predict an individual's measured-HRmax .

Race differences in age-trends of autonomic nervous system functioning

OBJECTIVE

The objective of this study was to consider race differences in age-trends of autonomic nervous system functioning, using a national data set with a broad age range.

METHODS

Measures of baseline heart rate variability (HRV) and HRV reactivity were derived from electrocardiograph (ECG) recordings taken at rest and during cognitive stress tasks. Age-trends in HRV and HRV reactivity were compared among 204 African Americans and 833 Whites ages 34 to 83 years (M = 53.7, SD = 11.4), before and after controlling for socioeconomic status (SES).

RESULTS

For HRV-reactivity, age-trends were steeper among African Americans and lower SES participants than Whites and higher SES participants. For baseline HRV, age-trends varied by SES but not race.

DISCUSSION

Results relating to HRV-reactivity (but not baseline HRV) were consistent with hypotheses suggesting that African Americans are exposed to higher levels of stress and experience accelerated declines in health across the life span. The relevance of the findings to research on social stress and health disparities is discussed.

Heart rate variability today

Heart rate variability (HRV) non-invasively assesses the activity of the autonomic nervous system. During the past 30 years, an increasing number of studies have related the imbalance of the autonomic nervous system (as assessed by HRV) to several pathophysiogical conditions, particularly in the setting of cardiovascular disease. Sudden death, coronary artery disease, heart failure, or merely cardiovascular risk factors (smoking, diabetes, hyperlipidemia, and hypertension) are the best-known clinical circumstances that can affect and/or be affected by the autonomic nervous system. Analyses of HRV variables have been proposed as a component of the clinical evaluation for patient risk stratification due to its independent prognostic information. Yet the potential for HRV to be used widely in clinical practice remains to be established.