Measures Of Respiratory Sinus Arrhythmia Research Articles

Depressive symptomatology and respiratory sinus arrhythmia in a non-clinical sample of middle-aged African Americans

Decreased heart rate variability and depression are both independent risk factors for cardiac mortality in clinical and non-clinical samples. The purpose of the current study is to examine the hypothesis that severity of depressive symptomatology is inversely associated with respiratory sinus arrhythmia (RSA) in a non-clinical sample of African Americans. The sample included 77 African Americans with a mean age of 48.4 (SD=11.7). Participants completed the Beck Depression Inventory-II (BDI-II) and a 5-min resting baseline measurement of RSA was collected. The BDI-II total score was positively associated with RSA (β=.334, p=.008). Given the unexpected direction of the association, we separated the BDI-II into cognitive and somatic affective subscales to identify which construct was driving the relationship. The somatic affective, was related to RSA (β=.328, p=.010), but not the cognitive subscale. Given this unexpected positive result, future research should further examine the nature of the relationship between depressive symptomatology and RSA in African Americans, as the relationship may vary based on levels of depressive symptomatology.

Respiratory sinus arrhythmia, effortful control, and parenting as predictors of children's sympathy across early childhood.

The goal of this study was to examine physiological and environmental predictors of children's sympathy (an emotional response consisting of feelings of concern or sorrow for others who are distressed or in need) and whether temperamental effortful control mediated these relations. Specifically, in a study of 192 children (23% Hispanic; 54% male), respiratory sinus arrhythmia (RSA), a measure thought to reflect physiological regulation, and observed authoritative parenting (both at 42 months) were examined as predictors of children's effortful control (at 54 months) and, in turn, children's sympathy (at 72 and 84 months). Measures of both baseline RSA and RSA suppression were examined. In a structural equation model, observed parenting was positively related to children's subsequent sympathy through its positive relation to effortful control. Furthermore, the indirect path from baseline RSA to higher sympathy through effortful control was marginally significant. Authoritative parenting and baseline RSA uniquely predicted individual differences in children's effortful control. Findings highlight the potential role of both authoritative parenting and physiological regulation in the development of children's sympathy.

Subtyping attention-deficit/hyperactivity disorder using temperament dimensions: toward biologically based nosologic criteria.

Psychiatric nosology is limited by behavioral and biological heterogeneity within existing disorder categories. The imprecise nature of current nosologic distinctions limits both mechanistic understanding and clinical prediction. We demonstrate an approach consistent with the National Institute of Mental Health Research Domain Criteria initiative to identify superior, neurobiologically valid subgroups with better predictive capacity than existing psychiatric categories for childhood attention-deficit/hyperactivity disorder (ADHD). To refine subtyping of childhood ADHD by using biologically based behavioral dimensions (i.e., temperament), novel classification algorithms, and multiple external validators. A total of 437 clinically well-characterized, community-recruited children, with and without ADHD, participated in an ongoing longitudinal study. Baseline data were used to classify children into subgroups based on temperament dimensions and examine external validators including physiological and magnetic resonance imaging measures. One-year longitudinal follow-up data are reported for a subgroup of the ADHD sample to address stability and clinical prediction. Parent/guardian ratings of children on a measure of temperament were used as input features in novel community detection analyses to identify subgroups within the sample. Groups were validated using 3 widely accepted external validators: peripheral physiological characteristics (cardiac measures of respiratory sinus arrhythmia and pre-ejection period), central nervous system functioning (via resting-state functional connectivity magnetic resonance imaging), and clinical outcomes (at 1-year longitudinal follow-up). The community detection algorithm suggested 3 novel types of ADHD, labeled as mild (normative emotion regulation), surgent (extreme levels of positive approach-motivation), and irritable (extreme levels of negative emotionality, anger, and poor soothability). Types were independent of existing clinical demarcations including DSM-5 presentations or symptom severity. These types showed stability over time and were distinguished by unique patterns of cardiac physiological response, resting-state functional brain connectivity, and clinical outcomes 1 year later. Results suggest that a biologically informed temperament-based typology, developed with a discovery-based community detection algorithm, provides a superior description of heterogeneity in the ADHD population than does any current clinical nosologic criteria. This demonstration sets the stage for more aggressive attempts at a tractable, biologically based nosology.

Heart Rate Variability Biofeedback Improves Cardiorespiratory Resting Function During Sleep

The present study was designed to examine the effect of heart rate variability (HRV) biofeedback on the cardiorespiratory resting function during sleep in daily life. Forty-five healthy young adults were randomly assigned to one of three groups: HRV biofeedback, Autogenic Training(AT), and no-treatment control. Participants in the HRV biofeedback were instructed to use a handheld HRV biofeedback device before their habitual bedtime, those in the AT were asked to listen to an audiotaped instruction before bedtime,and those in the control were asked to engage in their habitual activity before bedtime. Pulse wave signal during sleep at their own residences was measured continuously with a wrist watch-type transdermal photoelectric sensor for three time points. Baseline data were collected on the first night of measurements, followed by two successive nights for HRV biofeedback, AT, or control. Cardiorespiratory resting function was assessed quantitatively as the amplitude of high frequency(HF) component of pulse rate variability, a surrogate measure of respiratory sinus arrhythmia. HF component increased during sleep in the HRV biofeedback group,although it remained unchanged in the AT and control groups. These results suggest that HRV biofeedback before sleep may improve cardiorespiratory resting function during sleep.

Behavioral and Psychophysiological Responsiveness During Child Feeding in Mothers with Histories of Eating Disorders: A Pilot Study

The aim of this pilot project was to describe maternal responsiveness during child feeding in mothers with eating disorder histories through the combined use of observational, self-report, and physiologic methods. For this non-randomized cohort pilot study, 25 mothers with histories of eating disorders and 25 mothers with no history of an eating disorder with children ages 6-36 months were selected such that the groups were similar based on child age group (within 6 months) and child sex. Maternal behavioral responsiveness to child cues was assessed by video-recording and behavioral coding of both a free-play and feeding episode. Physiologic engagement was assessed through measurement of respiratory sinus arrhythmia (RSA) reactivity during free-play and feeding episodes. No differences were detected in observed behavioral responsiveness during feeding or free-play in mothers with eating disorder histories compared with controls. Mothers with eating disorder histories did report more parenting stress, increased anxiety, and exhibited a blunted physiologic stress response (less RSA reactivity) during both feeding and free-play interactions with their children. These results support future larger-scale investigations of RSA reactivity in mothers with eating disorders.

Sex differences in blood pressure control during 6° head-down tilt bed rest

Spaceflight-induced orthostatic intolerance has been studied for decades. Although ∼22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps.

Respiratory sinus arrhythmia responses to induced emotional states: Effects of RSA indices, emotion induction method, age, and sex

The literature shows large inconsistencies in respiratory sinus arrhythmia (RSA) responses to induced emotional states. This may be caused by differences in emotion induction methods, RSA quantification, and non-emotional demands of the situation. In 83 healthy subjects, we studied RSA responses to pictures and film fragments eliciting six different discrete emotions relative to neutral baseline stimuli. RSA responses were quantified in the time and frequency domain and were additionally corrected for differences in mean heart rate and respiration rate, resulting in eight different RSA response measures. Subjective ratings of emotional stimuli and facial electromyographic responses indicated that pictures and film fragments elicited the intended emotions. Although RSA measures showed various emotional effects, responses were quite heterogeneous and frequently nonsignificant. They were substantially influenced by methodological factors, in particular time vs. frequency domain response measures, correction for changes in respiration rate, use of pictures vs. film fragments, and sex of participants.

Evidence-based intervention for young children born premature: Preliminary evidence for associated changes in physiological regulation

The current study examined whether changes in maternal behaviors following an evidence-based treatment—Parent–Child Interaction Therapy (PCIT)—was associated with improvements in cardiac vagal regulation in young children born premature. Participants included 28 young children (mean age=37.79 months) that were born premature and presented with elevated externalizing behavior problems. To assess cardiac vagal regulation, resting measures of respiratory sinus arrhythmia (RSA) and RSA change (withdrawal or suppression) to a clean-up task were derived pre and post-treatment. Results indicated that an increase in behaviors mothers are taught to use during treatment (i.e., do skills—praise, reflection, and behavioral descriptions) was associated with an improvement in children's post-treatment RSA suppression levels. The current study illustrates the important role of caregiver behavior in promoting physiological regulation in children born premature.

Test–retest reliability of regional electroencephalogram (EEG) and cardiovascular measures in social anxiety disorder (SAD)

Although the search for psychophysiological manifestations of social anxiety has a rich history, there appear to be no published reports examining the reliability of continuous electrocortical measures that putatively index stress vulnerability and stress reactivity in socially anxious individuals. We examined the 1-week test–retest reliability of regional electroencephalogram (EEG) alpha asymmetry and power, respiratory sinus arrhythmia (RSA), heart period, and heart period variability measures at rest and during anticipation of an impromptu speech in 26 adults diagnosed with social anxiety disorder (SAD). Across the 1-week time period, we found medium-to-large correlations for regional EEG asymmetry and large correlations for regional EEG alpha power, RSA, heart period, and heart period variability measures at rest and during speech anticipation, before and after accounting for age and medication status. These results are similar to patterns observed in nonclinical samples and appear to provide the first documented evidence of test–retest reliability of psychophysiological measures that index central nervous system activity in socially anxious individuals. These findings also provide support for the notion that resting frontal EEG asymmetry and RSA constitute relatively stable individual differences in this clinical population.

Cardio-ventilatory coupling in young healthy resting subjects

In this work, cardio-ventilatory coupling (CVC) refers to the statistical relationship between the onset of either inspiration (I) or expiration (E) and the timing of heartbeats (R-waves) before and after these respiratory events. CVC was assessed in healthy, young (<45 yr), resting, supine subjects (n = 19). Four intervals were analyzed: time from I-onset to both the prior R-wave (R-to-I) and the following R-wave (I-to-R), as well as time from E-onset to both the prior R-wave (R-to-E) and following R-wave (E-to-R). The degree of coupling was quantified in terms of transformed relative Shannon entropy (tRSE), and χ(2) tests based on histograms of interval times from 200 breaths. Subjects were studied twice, from 5 to 27 days apart, and the test-retest reliability of CVC measures was computed. Several factors pointed to the relative importance of the R-to-I interval compared with other intervals. Coupling was significantly stronger for the R-to-I interval, coupling reliability was largest for the R-to-I interval, and only tRSE for the R-to-I interval was correlated with height, weight, and body surface area. The high test-retest reliability for CVC in the R-to-I interval provides support for the hypothesis that CVC strength is a subject trait. Across subjects, a peak ~138 ms prior to I-onset was characteristic of CVC in the R-to-I interval, although individual subjects also had earlier peaks (longer R-to-I intervals). CVC for the R-to-I interval was unrelated to two separate measures of respiratory sinus arrhythmia (RSA), suggesting that these two forms of coupling (CVC and RSA) are independent.

Effect of Postural Changes on Cardiorespiratory Coordination in Humans

In this study we assessed the effect of body postural changes from the supine (Sup) to the upright (Up) position on the magnitude and phase of respiratory sinus arrhythmia (RSA) and the phase-locking between the heart rhythm and respiration. In eight healthy human subjects, electrocardiograms (ECG) and respiratory signals were recorded. The magnitude and phase of RSA were evaluated by selective averaging of R-R interval changes from multiple respiratory cycles over the respiratory phase. For the assessment of cardiorespiratory coordination, we analyzed the phase-locking between heart rate, computed from R-R intervals of ECG, and respiratory rate, computed from intervals of inspiratory onsets of respiration, using Hilbert transform. A significant decrease in the magnitude of RSA and percentage and duration of phase-locking between heart rate and respiratory rate was observed during Up as compared to Sup. Further, there was a significant increase in the phase of RSA during Up as compared to Sup. In conclusion, measures of RSA and interaction between cardiac and respiratory rhythms are affected by body posture in humans.

Cardiovascular Regulation Profile Predicts Developmental Trajectory of BMI and Pediatric Obesity

The present study examined the role of cardiovascular regulation in predicting pediatric obesity. Participants for this study included 268 children (141 girls) obtained from a larger ongoing longitudinal study. To assess cardiac vagal regulation, resting measures of respiratory sinus arrhythmia (RSA) and RSA change (vagal withdrawal) to three cognitively challenging tasks were derived when children were 5.5 years of age. Heart period (HP) and HP change (heart rate (HR) acceleration) were also examined. Height and weight measures were collected when children were 5.5, 7.5, and 10.5 years of age. Results indicated that physiological regulation at age 5.5 was predictive of both normal variations in BMI development and pediatric obesity at age 10.5. Specifically, children with a cardiovascular regulation profile characterized by lower levels of RSA suppression and HP change experienced significantly greater levels of BMI growth and were more likely to be classified as overweight/at-risk for overweight at age 10.5 compared to children with a cardiovascular regulation profile characterized by high levels of RSA suppression and HP change. However, a significant interaction with racial status was found suggesting that the association between cardiovascular regulation profile and BMI growth and pediatric obesity was only significant for African-American children. An autonomic cardiovascular regulation profile consisting of low parasympathetic activity represents a significant individual risk factor for the development of pediatric obesity, but only for African-American children. Mechanisms by which early physiological regulation difficulties may contribute to the development of pediatric obesity are discussed.

Underestimation of cardiac vagal control in regular exercisers by 24-hour heart rate variability recordings

Objective To examine whether ceiling effects at long inter beat intervals (IBIs)cause an underestimation of cardiac vagal control in regular exercisers by time and frequency-domain measures of respiratory sinus arrhythmia (RSA). Methods 24-hour ECG and respiration recordings were performed in 26 regularly exercising subjects, actively engaged in aerobic training for the past year, and enrolled in supervised training in the six weeks pre-study, and in 26 age- and sex-matched non-exercisers. Sleep and waking levels of cardiac vagal control were estimated by RSA obtained through the peak–valley method, by the standard deviation of the IBIs, the root mean square of successive IBIs, and the high frequency IBI spectral power. Results In 11 of the exercisers the IBI–RSA relationship was characterized by a quadratic relationship. This reflected a ceiling effect at very long IBI values attained by regular exercisers, particularly during the nighttime recording. Irrespective of this ceiling effect, RSA as well as other heart rate variability (HRV) measures was still significantly larger in the exercisers with a quadratic IBI–RSA relationship than in non-exercisers or exercisers with a linear IBI–RSA relationship. Conclusions We conclude that a subgroup of regular exercisers is characterized by a low heart rate paired to high levels of cardiac vagal control. In these exercisers, vagal control is underestimated from HRV measures in ambulatory recordings. Inspection of the IBI–RSA relationship should be routinely added when HRV measures are used to index cardiac vagal control.

Emotion Regulation via the Autonomic Nervous System in Children with Attention-Deficit/Hyperactivity Disorder (ADHD)

Despite growing interest in conceptualizing ADHD as involving disrupted emotion regulation, few studies have examined the physiological mechanisms related to emotion regulation in children with this disorder. This study examined parasympathetic and sympathetic nervous system reactivity via measures of respiratory sinus arrhythmia (RSA) and cardiac pre-ejection period (PEP) in children with ADHD (n=32) and typically developing controls (n=34), using a novel emotion task with four conditions: negative induction, negative suppression, positive induction, and positive suppression of affect. Both groups showed strong task-response effects in RSA. However, typically developing children showed systematic variation in parasympathetic activity (RSA) depending on both emotion valence (more activation for negative emotion, reduced activation for positive emotion) and task demand (more activation for suppression than induction). In contrast, children with ADHD displayed a stable pattern of elevated parasympathetic activity (RSA) across all task conditions compared to baseline. No group differences in sympathetic activity (PEP) were observed. It is concluded ADHD in childhood is associated with abnormal parasympathetic mechanisms involved in emotion regulation.

Mapping cardiac physiology and parenting processes in maltreating mother–child dyads.

Child maltreatment (CM) lies on an extreme end of the continuum of parenting-at-risk, and while CM has been linked with a variety of behavioral indicators of dysregulation in children, less is known about how physiological markers of regulatory capacity contribute to this association. The present study examined patterns of mother and child physiological regulation and their relations with observed differences in parenting processes during a structured interaction. Abusing, neglecting, and non-CM mothers and their 3- to 5-year-old children completed a resting baseline and moderately challenging joint task. The structural analysis of social behavior was used to code mother-child interactions while simultaneous measures of respiratory sinus arrhythmia were obtained. Results indicated that physically abusive mothers were more likely to react to children's positive bids for autonomy with strict and hostile control, than either neglecting or non-CM mothers. CM exposure and quality of maternal responding to children's autonomous bids were uniquely associated with lower parasympathetic tone in children. Results provide evidence of neurodevelopmental associations between early CM exposure, the immediate interactive context of parenting, and children's autonomic physiology.

Efficient and cost‐effective estimation of the influence of respiratory variables on respiratory sinus arrhythmia

Researchers are interested in respiratory sinus arrhythmia (RSA) as an index of cardiac vagal activity. Yet, debate exists about how to account for respiratory influences on quantitative indices of RSA. T. Ritz, M. Thons, and B. Dahme (2001) developed a within-individual correction procedure by which the effects of respiration on RSA may be estimated using regression models. We replicated their procedure substituting a spectral high-frequency measure of RSA for a time-domain statistic and a respiratory belt's relative measure of tidal volume for the direct assessment provided by a pneumotachograph. The standardized slopes from the respiratory belt and pneumotachography-derived regression equations (estimated across a 6-min paced breathing protocol) were positively correlated (r=0.93, p<.001); correlations were similar across 2- and 4-min time courses parsed from the 6-min protocol. Our results offer methodological alternatives to the research community.

Dynamic measures of RSA predict distress and regulation in toddlers

In this study, we examined a new method for quantifying individual variability using dynamic measures of respiratory sinus arrhythmia (RSA). This method incorporated temporal variation into the measurement of RSA and provided information beyond that offered by more traditional quantifications such as difference scores. Dynamic and static measures of change in RSA were tested in relation to displays of emotion and affective behaviors during a fear-eliciting episode in a sample of 88 typically developing and high-fear toddlers during a laboratory visit at age 24 months. Dynamic measures of RSA contributed information that was unique from traditionally employed, static change scores in predicting high-fear toddlers' displays of shyness during a fear-eliciting episode. In contrast, RSA change scores offered information related to boldness in nonhigh-fear children. In addition, several associations included estimates of nonlinear change in RSA. Implications for the study of individual differences in RSA and relations with emotion and emotion regulation are discussed.

The association between prenatal cocaine exposure and physiological regulation at 13 months of age.

This study examined the association between prenatal cocaine exposure (PCE) and autonomic regulation at 13 months of age. Measures of respiratory sinus arrhythmia (RSA) were obtained from 156 (79 exposed, and 77 nonexposed) infants during baseline and during tasks designed to elicit positive (PA) and negative affect (NA). There was a significant suppression of RSA during the negative affect task for nonexposed infants but not for exposed infants. Maternal symptoms of depression or anxiety (MDA) did not mediate this association. However, gender and MDA did moderate this association such that exposed boys and exposed infants whose mothers had higher levels of MDA had an increase in RSA during a task designed to elicit NA rather than the typical pattern of RSA suppression. These results suggest that there are several possible pathways from PCE to physiological dysregulation during late infancy.

Kramers-Moyal coefficients in the analysis and modeling of heart rate variability

Modeling of recorded time series may be used as a method of analysis for heart rate variability studies. In particular, the extraction of the first two Kramers-Moyal coefficients has been used in this context. Recently, the method was applied to a wide range of signal analysis: from financial data to physiological and biological time series. Modeling of the signal is important for the prediction and interpretation of the dynamics underlying the process. The method requires the determination of the Markov time. Obtaining the drift and diffusion term of the Kramers-Moyal expansion is crucial for the modeling of the original time series with the Langevin equation. Both Tabar [Comput. Sci. Eng. 8, 54 (2006)] and T. Kuusela [Phys. Rev. E 69, 031916 (2004)] suggested that these terms may be used to distinguish healthy subjects from those with heart failure. The research groups applied a somewhat different methodology and obtained substantially different ranges of the Markov time. We show that the two studies may be considered consistent with each other as Kuusela analyzed 24 h recordings while Tabar analyzed daytime and nighttime recordings, separately. However, both groups suggested using the Langevin equation for modeling of time series which requires the fluctuation force to be a Gaussian. We analyzed heart rate variability recordings for ten young male (age 26-4+3 y ) healthy subjects. 24 h recordings were analyzed and 6-h-long daytime and nighttime fragments were selected. Similar properties of the data were observed in all recordings but all the nighttime data and seven of the ten 24 h series exhibited higher-order, non-negligible Kramers-Moyal coefficients. In such a case, the reconstruction of the time series using the Langevin equation is impossible. The non-negligible higher-order coefficients are due to autocorrelation in the data. This effect may be interpreted as a result of a physiological phenomenon (especially occurring for nighttime data): respiratory sinus arrhythmia (RSA). We detrended the nighttime recordings for the healthy subjects and obtained an asymmetry in the dependence of the diffusion term on the rescaled heart rate. This asymmetry seems to be an effect of different time scales during the inspiration and the expiration phase of breathing. The asymmetry was significantly decreased in the diffusion term found for detrended nighttime recordings obtained from five hypertrophic cardiomyopathy (HCM) patients. We conclude that the effect of RSA is decreased in the heart rate variability of HCM patients-a result which may contribute to a better medical diagnosis by supplying a new quantitative measure of RSA.

A randomized controlled trial of a controlled breathing protocol on heart rate variability following myocardial infarction or coronary artery bypass graft surgery

Objectives: To determine whether a controlled breathing programme increases heart rate variability following an acute myocardial infarction and/or coronary artery bypass graft surgery. Rationale: Heart rate variability is reduced following a myocardial infarction, and low heart rate variability is associated with a high mortality risk. By changing tidal volume and rate of breathing, individuals can alter beat-to-beat heart rate variability. It is hypothesized that heart rate increases with inspiration and decreases with exhalation, and that deep slow breathing enhances respiratory sinus arrhythmia, increasing heart rate variability. Design: Randomized controlled trial. Setting: Cardiac rehabilitation programme at a large academic medical centre in North Texas. Subjects: From 2001 to 2005, 44 patients, age 46—65 years, who had a myocardial infarction and/or undergone coronary artery bypass graft surgery 1—8 weeks previously and were referred to the Cardiac Rehabilitation Program. Intervention: Patients were randomized to either usual cardiac rehabilitation or cardiac rehabilitation with controlled breathing (6 breaths/min for 10 minutes twice daily during the eight-week treatment period). Main measures: Weekly measurements of total power and standard deviation of the mean normal to normal RR interval (SDNN), and fortnightly measurements of respiratory sinus arrhythmia were taken using Biocom Technologies Heart Rhythm Scanner and Tracker software. Results: No significant difference in change were seen between groups in SDNN (P = 0.3984), baseline respiratory sinus arrhythmia (P = 0.6556) or total power (P = 0.6184). Conclusion: Results suggest participation in the controlled breathing programme offered no additional benefit in increasing heart rate variability following myocardial infarction or coronary artery bypass graft surgery. However, 77% of study patients were on heart rate-lowering medications, which may have masked changes in heart rate variability.