Heart Rate Asymmetry Research Articles

Emotion regulation abilities as a predictor of anxiety, positive emotions, heart rate, and alpha asymmetry during an impromptu speech task

ABSTRACT Background and Objectives Recent approaches suggest that emotion regulation (ER) abilities represent potential predictors of emotional response among youths navigating stressful situations. To test this, we investigated whether ER abilities predicted the subjective and physiological emotional response experienced by youths during a stressful situation. Design A cross-sectional design was employed. Method One hundred and thirty-four youths completed measures of ER abilities (emotional awareness, anxiety sensitivity, emotional control) and were asked to deliver a speech while their anxiety, positive emotions, heart rate, and alpha asymmetry were collected at four time points: baseline, anticipation, speech, and post-recovery. Results Pearson r correlations showed that poor emotional control and awareness, as well as high anxiety sensitivity were related to greater anxiety and lower positive emotions experienced during the speech. Hierarchical multiple regressions also revealed that emotional control and emotional awareness predicted greater speech anxiety and lower positive emotions. Moreover, anxiety sensitivity was related to and predicted an increased heart rate experienced during speech. Conclusions Findings suggest that difficulties in emotional awareness, anxiety sensitivity, and emotional control predict the emotional response experienced by youths during a stressful situation. Interventions delivered by clinicians/teachers that target ER difficulties may be effective in improving emotional functioning when navigating stressful situations.

Rationale, design and methods planned in a prospective study concerning the circadian rhythm of heart rate asymmetry in healthy subjects

Heart rate asymmetry (HRA) is a physiological phenomenon caused by an unequal (asymmetric) contribution of heart rate decelerations and accelerations to the variability (variance) and microstructure of the heart rhythm of sinus origin. HRA has been studied in healthy people and patients with heart failure, diabetes, obstructive sleep apnoea, ischaemic heart disease, and survivors of myocardial infarction. HRA is a particular form of the heart rate variability (HRV) phenomenon related to the changes in the duration of cardiac cycles of sinus origin. HRV is influenced by physical activity, age, gender or time of day. It has been reported that HRA expression differs between day and night. However, its circadian rhythm has not been analysed so far. Moreover, the differences in HRA expression related to gender, level of physical activity or age have not been investigated either. With this study, we aim to explore the circadian rhythm of the HRA features, as well as the relation of the HRA expression to gender, physical activity, sleep pattern and body composition in a group of at least 100 healthy adults of both sexes aged between 19 and 60. This study might provide reference values for HRA as well as confirming or dismissing the existence of circadian rhythm of this physiological phenomenon.

Asymmetric properties of heart rate microstructure

The duration of each cardiac cycle is measured on ECG as the distance between the peaks of consecutive R waves (RR interval). Its inverse value corresponds to the heart rate (HR) changing in a beat-to-beat manner. HR accelerations are reflected as the shortenings of RR intervals while HR decelerations as the lengthening of RR intervals. HR asymmetry is a physiological phenomenon caused by an unequal input of HR decelerations and accelerations to the HR variability. Naturally occurring consecutive values of RR intervals create time series which are composed of acceleration and deceleration runs of different length. Some examples are a single HR acceleration, a pair of HR decelerations, a run consisting of five consecutive HR decelerations or a run composed of eight accelerations in a row. These runs make up the so-called heart rate microstructure that has asymmetric properties due to unequal contribution of acceleration and deceleration runs. Asymmetry of HR microstructure is a physiological finding in healthy people. However, the asymmetric properties of HR microstructure have been shown to significantly alter in some clinical conditions such as myocardial infarction, obstructive sleep apnea, chronic obturatory pulmonary disease or sepsis in infants. An abnormal HR microstructure has predictive value in survivors of myocardial infarction or patients with clinical indications for exercise treadmill stress test, e.g., for total mortality. In this review, we present and explain how the asymmetric properties of HR microstructure can be quantified, and summarise available data on the clinical and predictive value of this phenomenon and its analysis.

Asymmetric spread of heart rate variability

ObjectiveThe variability related to acceleration and deceleration of heart rate contributes unevenly to the overall heart rate variability (HRV). Thus, the spread of heart rate is asymmetric. Despite developing several heart rate asymmetry (HRA) measures, none examines this disparity in HRV. Therefore, a new HRA measure, asymmetric spread index (ASI), is proposed to measure asymmetry in the variability of heart rate associated with acceleration and deceleration. HRA generally arises due to cardiac autonomic modulation. However, the exact underlying phenomenon is unknown. Therefore, the study of HRA is performed in cardiac pathologies, synthetic HRV signals, and meditation. MethodsLike other HRA measures, ASI is defined by using the Poincaré plot. The surrogate data analysis was performed to examine that ASI represents a physiological phenomenon and not an artifact of the method. Statistical analysis and receiver operating characteristic analysis were performed for evaluating the performance of HRA indices. ResultsHRA is found increased in patients with heart failure and arrhythmia. Synthetic HRV signals show less asymmetry than real HRV signals. The HRA increases during meditation. Experimental results indicate that variability shifts from the acceleration part to the deceleration part during meditation, and vice versa. ConclusionThe ASI quantifies the uneven spread of heart rate that would remain unexplored with existing asymmetric measures. It shows better discriminating power than existing HRA. SignificanceSince HRA is a new area, further studies are required to establish its clinical significance. The ASI may help in understanding the underlying mechanism of HRA.

Heart rate, electrodermal responses and frontal alpha asymmetry to accepted and non-accepted solutions and drinks

Consumers’ physiological responses, such as heart rate, electrodermal responses and frontal alpha activity can enhance the understanding of the consumers’ food experience. This study looked at physiological responses of the autonomic nervous system (heart rate, electrodermal responses) as a measure for level of arousal, and to responses of the central nervous system (frontal alpha asymmetry, FAA) as a measure for approach/withdrawal motivational tendency, to accepted (liked) and non-accepted (disliked) solutions and drinks.Participants (n = 32, age range: 18–34 years) were presented with a universally accepted (sucrose) and non-accepted (caffeine) solution, a personally selected accepted and non-accepted drink, and plain water. Heart rate, heart rate variability, electrodermal activity and electro-encephalography for FAA at F7 and F8 (10/20 system, 25 channels, 256 Hz) were registered during tasting. Statistical analysis consisted of linear mixed model analyses.We found a significantly higher heart rate during tasting of the personally selected non-accepted drink and a significantly lower latency of the electrodermal response during tasting of the universally non-accepted solution and personally selected non-accepted drink. No significant results were observed for FAA.This is one of the first studies that examined physiological responses including frontal alpha asymmetry during actual tasting. This study provides an exploratory method to obtain implicit measurement of acceptance and food product-elicited emotion through physiological responses and supports the importance of the inclusion of implicit measures, next to explicit measures, in sensory evaluation of food products.

Asymmetry of lagged Poincare plot in heart rate signals during meditation

Background and aimHeart rate variability (HRV) quantifies the variability in the heart’s beat-to-beat intervals. This signal is a potential marker of cardiac function in normal, pathological, and psychological states. Signal asymmetry refers to an unequal distribution in the signal, which can be found by a two-dimensional Poincare plot. Earlier, heart rate asymmetry (HRA) was assessed using a conventional Poincare plot (lag of 1). In this study, we have investigated the effect of delay on the phase space asymmetry using lagged Poincare’s plot. Experimental procedureThis study compared the presence/lack of asymmetries in the HRV data of 12 meditators (four Kundalini yoga (Yoga) at an advanced level of meditation, eight Chinese Chi meditators (Chi) ∼1–3 months) to 25 non-meditators (11 spontaneous nocturnal breathing (Normal) and 14 metronomic breathing (Metron)). Poincare’s plots were constructed with six different lags, and HRA was calculated. The analysis was conducted using HRV data provided in the Physionet database. ResultsThe results showed that using conventional Poincare’s plot (lag of 1), the lowest HRA was observed in the Metron group. In addition, the HRA index was different between meditators and non-meditator groups. Moreover, as the most significant difference between groups was observed in a delay of 6, the role of the delay selection on the signal asymmetry was revealed. ConclusionThe difference between lagged HRA responses on Yoga in comparison with other groups can be an emphasis on the importance of choosing the type of meditation technique and its effects on the cardiovascular system.

Testing heart rate asymmetry in long, nonstationary 24 hour RR-interval time series

Objective: Heart rate asymmetry is a phenomenon in which the contribution of heart rate decelerations to short-term heart rate variability is greater than that of accelerations, and the contribution of accelerations to long-term and total variability is greater than that of decelerations. This has been established for short, stationary recordings, so our aim is to do it for long recordings. Approach: In this paper, we analyze heart rate asymmetry in 87 long, 24 h electrocardiogram Holter recordings from healthy people. We show that in the whole recording all types of asymmetry are observable, clear and highly statistically significant. To analyze the local changes of asymmetry in time, we analyzed the recordings by disjoint jumping windows of 300 beats. Main results: This analysis revealed that the local, averaged measures of all types of asymmetry also demonstrate its presence which is highly statistically significant. Additionally, we introduce in this paper a statistical test for asymmetry in a single long recording, as opposed to the current approach in which whole groups are tested. We do this by introducing the proportion of time spent in asymmetry for each recording and using it in the binomial tests. Significance: We found that for all the recordings most of the time is spent in asymmetry.

Differentiation of Heart Failure Patients by the Ratio of the Scaling Exponents of Cardiac Interbeat Intervals.

Heart failure (HF) is one of the most frequent heart diseases. It is usually characterized with structural and functional cardiac abnormalities followed by dysfunction of autonomic cardiac control. Current methods of heartbeat interval analysis are not capable to differentiate HF patients and some new differentiation of HF patients could be useful in the determination of the direction of their treatment. In this study, we examined potential of the ratio of the short-term and long-term scaling exponents (α1 and α2) to separate HF patients with similar level of reduced cardiac autonomic nervous system control and with no significant difference in age, left ventricular ejection fraction (LVEF) and NYHA class. Thirty-five healthy control subjects and 46 HF patients underwent 20 min of continuous supine resting ECG recording. The interbeat interval time series were analyzed using standardized power spectrum analysis, detrended fluctuation analysis method and standard Poincaré plot (PP) analysis with measures of asymmetry of the PP. Compared with healthy control group, in HF patients linear measures of autonomic cardiac control were statistically significantly reduced (p < 0.05), heart rate asymmetry was preserved (Cup > Cdown, p < 0.01), and long-term scaling exponent α2 was significantly higher. Cluster analysis of the ratio of short- and long-term scaling exponents showed capability of this parameter to separate four clusters of HF patients. Clusters were determined by interplay of presence of short-term and long-term correlations in interbeat intervals. Complementary measure, commonly accepted ratio of the PP descriptors, SD2/SD1, showed tendency toward statistical significance to separate HF patients in obtained clusters. Also, heart rate asymmetry was preserved only in two clusters. Finally, a multiple regression analysis showed that the ratio α1/α2 could be used as an integrated measure of cardiac dynamic with complex physiological background which, besides spectral components as measures of autonomic cardiac control, also involves breathing frequency and mechanical cardiac parameter, left ventricular ejection fraction.

Impacts of reference points and reference lines on the slope- and area-based heart rate asymmetry analysis

Heart rate asymmetry (HRA) could capture valuable dynamical properties from the electrocardiographic RR interval time-series that are helpful for evaluating the cardiovascular functioning. Several metrics derived from the Poincaré plot have been established for assessing HRA such as the slope index (SI) and the area index (AI). In the current study, we aimed to examine how different reference points and reference lines affect the calculations of SI and AI. To understand their performance, two case studies that were to classify subjects with (1) arrhythmias and (2) congestive heart failure, respectively, from normal controls were performed. To examine whether these effects depend on data lengths, the case studies were performed on both long-term heartbeat interval time-series and short-term segments. Our results showed that different reference points or reference lines could strongly affect the performance of both SI and AI, especially when short-term data were being analyzed. Using the minimum of data as the reference point might be a conservative solution in application but a spectrum of SI or AI measurements with multiple reference points and reference lines are highly recommended.

Effects of emotions on heart rate asymmetry.

Heart rate asymmetry (HRA) is an index that accounts for an uneven contribution of decelerations and accelerations to the heart rate variability (HRV). Clinical studies indicated that HRA measures have additive clinical value over the more frequently used HRV indexes. Despite the abundance of studies on psychological influences on HRV, little is known whether psychological factors influence HRA. Based on previous research regarding HRA and stress, we expected that negative emotions compared to positive emotions would decrease the contribution of decelerations to HRV. Thirty female participants watched three clips that produced negative emotions, positive emotions, and neutral affect. Besides electrocardiogram, we measured several physiological and behavioral responses to ascertain the affective impact of the clips. Using the RR interval time series, we calculated HRV and HRA indexes. We found that HRA differentiated between positive emotions and negative emotions reactivity. Positive emotions produced a higher number of decelerations in short-term variability to the total short-term variability (C1d ) compared to negative emotions. Moreover, C1d correlated with subjective ratings of affect. In sum, the results of this study indicated that HRA is sensitive to psychological influences. HRA indexes are likely to contribute to a more nuanced physiological differentiation between emotions.

Heart rate asymmetry as a new marker for neonatal stress

Abstract The autocorrelation of the heart rate variability is presented by various methods and models, but Poincare plots remain valuable analytic tools. Heart rate asymmetry analysis (HRA) is used for the quantification of unevenly distributed points above and below the line of identity. The aim of this work is to implement HRA analysis in newborns, to use it as a marker for acute stress. Forty healthy term newborn infants were included in the study. The protocol included two baseline phases, and two stress phases (heel stimulation and heel stick blood sampling), during which the heart rate was measured. Additionally, to the standard HRA indices, a new index (SKG) related to the first differences of the RR interval time series is introduced. A ROC curve analysis was applied to test the diagnostic properties of the asymmetry indices. With AUC significantly different from 0.5, the results show that HRA indices may be used as clinical markers. With higher AUC values (0.906 and 0.785), accuracy (87.5% and 81.3%) and sensitivity (87.5% and 81.3%), the SKG index outperformed the traditional indices. This novel application of HRA shows potential benefit in stress assessment of newborns, and in nonverbal patients in general.

1D4-1 Analysis of Heart Rate Asymmetry (HRA) during mental workload

1D4-1 Analysis of Heart Rate Asymmetry (HRA) during mental workload

Does the Temporal Asymmetry of Short-Term Heart Rate Variability Change during Regular Walking? A Pilot Study of Healthy Young Subjects.

The acceleration and deceleration patterns in heartbeat fluctuations distribute asymmetrically, which is known as heart rate asymmetry (HRA). It is hypothesized that HRA reflects the balancing regulation of the sympathetic and parasympathetic nervous systems. This study was designed to examine whether altered autonomic balance during exercise can lead to HRA changes. Sixteen healthy college students were enrolled, and each student undertook two 5-min ECG measurements: one in a resting seated position and another while walking on a treadmill at a regular speed of 5 km/h. The two measurements were conducted in a randomized order, and a 30-min rest was required between them. RR interval time series were extracted from the 5-min ECG data, and HRA (short-term) was estimated using four established metrics, that is, Porta's index (PI), Guzik's index (GI), slope index (SI), and area index (AI), from both raw RR interval time series and the time series after wavelet detrending that removes the low-frequency component of <~0.03 Hz. Our pilot data showed a reduced PI but unchanged GI, SI, and AI during walking compared to resting seated position based on the raw data. Based on the wavelet-detrended data, reduced PI, SI, and AI were observed while GI still showed no significant changes. The reduced PI during walking based on both raw and detrended data which suggests less short-term HRA may underline the belief that vagal tone is withdrawn during low-intensity exercise. GI may not be sensitive to short-term HRA. The reduced SI and AI based on detrended data suggest that they may capture both short- and long-term HRA features and that the expected change in short-term HRA is amplified after removing the trend that is supposed to link to long-term component. Further studies with more subjects and longer measurements are warranted to validate our observations and to examine these additional hypotheses.

Cellular Phone Irradiation of the Head Affects Heart Rate Variability Depending on Inspiration/Expiration Ratio.

Mobile phones may have harmful health effects and clinical examinations report ambiguous results of exposure concerning neurophysiological and cardiovascular actions. This study investigated heart rate asymmetry (HRA) and heart rate variability (HRV) parameters with 1:2 and 1:1 metronome-paced inspiration/expiration ratios during short-term 1,800MHz GSM cellular phone exposure in 20 healthy volunteers. Significant HRA changes by Porta and Guzik indices were not found on exposure compared to sham exposure. Time-domain HRV parameters on exposure showed significant differences at 1:1 paced, but not at 1:2 paced breathing compared to sham exposure. A mild post-exposure effect was observed regarding root mean square of successive RR-differences. The findings reflect persisting acute effects of GSM handset emission on the autonomic nervous system. Exploring its influences on health status and survival needs further studies. Symmetrical breathing can be used as a sensitizing factor in other HRV/HRA analysis studies.

Modeling the 2D space of emotions based on the poincare plot of heart rate variability signal

Emotions mean accepting, understanding, and recognizing something with one's senses. The physiological signals generated from the internal organs of the body can objectively and realistically reflect changes in real-time human emotions and monitor the state of the body. In this study, the two-dimensional space-based emotion model was introduced on the basis of Poincare's two-dimensional plot of the signal of heart rate variability. Four main colors of psychology, blue, red, green, and yellow were used as a stimulant of emotion, and the ECG signals from 70 female students were recorded. Using extracted features of Poincare plot and heart rate asymmetry, two tree based models estimated the levels of arousal and valence with 0.05 mean square errors, determined an appropriate estimation of these two parameters of emotion. In the next stage of the study, four different emotions mean pleasure, anger, joy, and sadness, were classified using IF-THEN rules with the accuracy of 95.71%. The results show the color red is associated with more excitement and anger, while green has small anxiety. So, this system provides a measure for numerical comparison of mental states and makes it possible to model emotions for interacting with the computer and control mental states independently of the pharmaceutical methods.

Transcutaneous Carbon Dioxide Treatment Affects Heart Rate Variability - A Pilot Study.

The aim of this study was to investigate the effects of carbon-dioxide treatment on heart rate variability (HRV) parameters: mean RR interval (RRI), standard deviation of RR intervals (SDNN), root mean square of successive RR differences (RMSSD); and Porta and Guzik indices, as measures of heart rate asymmetry. Twenty patients were enrolled (mean±SD, age=59±7.8 years). Measurements were performed before CO2 treatment, at the beginning of treatment, at 15 min of treatment, immediately after and 1 h after the treatment. Significant increase in SDNN was found 1 h after the treatment when compared to that before it (p=0.011). There were no significant changes in other parameters. CO2 treatment can influence the autonomic nervous system identified by SDNN changes. However, larger studies are required to confirm these results.

Properties of Asymmetric Detrended Fluctuation Analysis in the time series of RR intervals

Heart rate asymmetry is a phenomenon by which the accelerations and decelerations of heart rate behave differently, and this difference is consistent and unidirectional, i.e. in most of the analyzed recordings the inequalities have the same directions. So far, it has been established for variance and runs based types of descriptors of RR intervals time series. In this paper we apply the newly developed method of Asymmetric Detrended Fluctuation Analysis, which so far has mainly been used with economic time series, to the set of 420 stationary 30 min time series of RR intervals from young, healthy individuals aged between 20 and 40. This asymmetric approach introduces separate scaling exponents for rising and falling trends. We systematically study the presence of asymmetry in both global and local versions of this method. In this study global means “applying to the whole time series” and local means “applying to windows jumping along the recording”. It is found that the correlation structure of the fluctuations left over after detrending in physiological time series shows strong asymmetric features in both magnitude, with α+<α−, where α+ is related to heart rate decelerations and α− to heart rate accelerations, and the proportion of the signal in which the above inequality holds. A very similar effect is observed if asymmetric noise is added to a symmetric self-affine function. No such phenomena are observed in the same physiological data after shuffling or with a group of symmetric synthetic time series.

Area asymmetry of heart rate variability signal

BackgroundHeart rate fluctuates beat-by-beat asymmetrically which is known as heart rate asymmetry (HRA). It is challenging to assess HRA robustly based on short-term heartbeat interval series.MethodAn area index (AI) was developed that combines the distance and phase angle information of points in the Poincaré plot. To test its performance, the AI was used to classify subjects with: (i) arrhythmia, and (ii) congestive heart failure, from the corresponding healthy controls. For comparison, the existing Porta’s index (PI), Guzik’s index (GI), and slope index (SI) were calculated. To test the effect of data length, we performed the analyses separately using long-term heartbeat interval series (derived from >3.6-h ECG) and short-term segments (with length of 500 intervals). A second short-term analysis was further carried out on series extracted from 5-min ECG.ResultsFor long-term data, SI showed acceptable performance for both tasks, i.e., for task i p < 0.001, Cohen’s d = 0.93, AUC (area under the receiver-operating characteristic curve) = 0.86; for task ii p < 0.001, d = 0.88, AUC = 0.75. AI performed well for task ii (p < 0.001, d = 1.0, AUC = 0.78); for task i, though the difference was statistically significant (p < 0.001, AUC = 0.76), the effect size was small (d = 0.11). PI and GI failed in both tasks (p > 0.05, d < 0.4, AUC < 0.7 for all). However, for short-term segments, AI indicated better distinguishability for both tasks, i.e., for task i, p < 0.001, d = 0.71, AUC = 0.71; for task ii, p < 0.001, d = 0.93, AUC = 0.74. The rest three measures all failed with small effect sizes and AUC values (d < 0.5, AUC < 0.7 for all) although the difference in SI for task i was statistically significant (p < 0.001). Besides, AI displayed smaller variations across different short-term segments, indicating more robust performance. Results from the second short-term analysis were in keeping with those findings.ConclusionThe proposed AI indicated better performance especially for short-term heartbeat interval data, suggesting potential in the ambulatory application of cardiovascular monitoring.

The degree of heart rate asymmetry is crucial for the validity of the deceleration and acceleration capacity indices of heart rate: A model-based study

The deceleration capacity (DC) and acceleration capacity (AC) of heart rate are a pair of indices used for evaluating the autonomic nervous system (ANS). We assessed the role of heart rate asymmetry (HRA) in defining the relative performance of DC and AC using a mathematical model, which is able to generate a realistic RR interval (RRI) time series with controlled ANS states. The simulation produced a set of RRI series with random sympathetic and vagal activities. The multi-scale DCs and ACs were computed from the RRI series, and the correlation of DC and AC with the ANS functions was analyzed to evaluate the performance of the indices. In the model, the HRA level was modified by changing the inspiration/expiration (I/E) ratio to examine the influence of HRA on the performances of DC and AC. The results show that on the conventional scales (T=1, s=2), an HRA level above 50% results in a stronger association of DC with the ANS, compared with AC. On higher scales (T=4, s=6), there was no HRA and DC showed a similar performance to AC for all I/E ratios. The data suggest that the HRA level determines which of DC or AC is the optimal index for expressing ANS functions. Future clinical applications of DC and AC should be accompanied by an HRA analysis to provide a better index for assessing ANS.

Analysis of fetal heart rate asymmetry before and after 35 weeks of gestation

In this study, we have investigated the evidence of fetal heart rate asymmetry and how the fetal heart rate asymmetry changes before and after 35 weeks of gestation. Noninvasive fetal electrocardiogram (fECG) signals from 45 pregnant women at the gestational age from16 to 41 weeks with normal single pregnancies were analysed. A nonlinear parameter called heart rate asymmetry (HRA) index that measures time asymmetry of RR interval time-series signal was used to understand the changes of HRA in early and late fetus groups. Results indicate that fetal HRA measured by Porta's Index (PI) consistently increases after 35 weeks gestation compared to foetus before 32 weeks of gestation. It might be due to significant changes of sympatho-vagal balance towards delivery with more sympathetic surge. On the other hand, Guzik's Index (GI) showed a mixed effect i.e., increases at lower lags and decreases at higher lags. Finally, fHRA could potentially help identify normal and the pathological autonomic nervous system development.