Effect Of Heart Rate Variability Research Articles

Enhancing diagnostic performance and image quality in coronary CT angiography: Impact of SnapShot Freeze 2 algorithm across varied heart rates in stent patients.

To investigate the enhancement of image quality achieved through the utilization of SnapShot Freeze 2 (SSF2), a comparison was made against the results obtained from the original SnapShot Freeze algorithm (SSF) and standard motion correction (STND) in stent patients undergoing coronary CT angiography (CCTA) across the entire range of heart rates. A total of 118 patients who underwent CCTA, were retrospectively included in this study. Images of these patients were reconstructed using three different algorithms: SSF2, SSF, and STND. Objective assessments include signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diameters of stents and artifact index (AI). The image quality was subjectively evaluated by two readers. Compared with SSF and STND, SSF2 had similar or even higher quality in the parameters (AI, SNR, CNR, inner diameters) of coronary artery, stent, myocardium, MV (mitral valve), TV (tricuspid valve), AV (aorta valve), and PV (pulmonary valve), and aortic root (AO). Besides the above structures, SSF2 also demonstrated comparable or even higher subjective scores in atrial septum (AS), ventricular septum (VS), and pulmonary artery root (PA). Furthermore, the enhancement in image quality with SSF2 was significantly greater in the high heart rate group compared to the low heart rate group. Moreover, the improvement in both high and low heart rate groups was better in the SSF2 group compared to the SSF and STND group. Besides, when using the three algorithms, an effect of heart rate variability on stent image quality was not detected. Compared to SSF and STND, SSF2 can enhance the image quality of whole-heart structures and mitigate artifacts of coronary stents. Furthermore, SSF2 has demonstrated a significant improvement in the image quality for patients with a heart rate equal to or higher than 85bpm.

Mediating Effect of Heart Rate Variability on the Relationship Between Anxiety Symptoms and Blood Pressure in Patients with Primary Hypertension.

Patients with hypertension (HTN) are at increased risk of developing cardiovascular disease, which can be reduced with blood pressure (BP) control. Anxiety can contribute to high BP and low heart rate variability (HRV). Although relationships between social support, self-rated health-status (SRHS), anxiety and measures of HRV and BP have been suggested, they have not been clearly established. This cross-sectional correlational study aimed to 1) examine relationships between social support, SRHS, and anxiety; and 2) examine if HRV mediated relationships between anxiety symptoms and BP. Patients with primary HTN were recruited from a cardiovascular outpatient clinic using convenience sampling (N = 300). Data included scale scores for SRHS, social support, and anxiety (Hospital Anxiety and Depression Scale). A handheld limb-lead electrocardiogram monitor measured HRV, using the ratio of low-frequency bands to high-frequency bands; an automatic sphygmomanometer measured systolic and diastolic blood pressure (SBP and DBP, respectively). Path analysis of structural equation models examined relationships between variables; the bootstrap method examined the mediating effects of HRV. Analysis showed scores for SRHS and social support had a direct effect on anxiety scores. Scores for anxiety directly affected HRV and BP. HRV also had a direct effect on BP. Bootstrapping indicated HRV mediated the relationship between anxiety symptoms and BP. The final model indicated SRHS, social support, and anxiety symptoms together explained 80% of SBP and 33% of DBP. These findings suggest HRV could be used to measure the effectiveness of strategies aimed at reducing anxiety and improving control of BP.

Effectiveness of Heart Rate Variability for Predicting Intradialytic Hypotension in Chronic Hemodialysis Patients

Effectiveness of Heart Rate Variability for Predicting Intradialytic Hypotension in Chronic Hemodialysis Patients

Daily heart rate variability biofeedback training decreases locus coeruleus MRI contrast in younger adults in a randomized clinical trial

As an arousal hub region in the brain, the locus coeruleus (LC) has bidirectional connections with the autonomic nervous system. Magnetic resonance imaging (MRI)-based measures of LC structural integrity have been linked to cognition and arousal, but less is known about factors that influence LC structure and function across time. Here, we tested the effects of heart rate variability (HRV) biofeedback, an intervention targeting the autonomic nervous system, on LC MRI contrast and sympathetic activity. Younger and older participants completed daily HRV biofeedback training for five weeks. Those assigned to an experimental condition performed biofeedback involving slow, paced breathing designed to increase heart rate oscillations, whereas those assigned to a control condition performed biofeedback to decrease heart rate oscillations. At the pre- and post-training timepoints, LC contrast was assessed using turbo spin echo MRI scans, and RNA sequencing was used to assess cAMP-responsive element binding protein (CREB)-regulated gene expression in circulating blood cells, an index of sympathetic nervous system signaling. We found that left LC contrast decreased in younger participants in the experimental group, and across younger participants, decreases in left LC contrast were related to the extent to which participants increased their heart rate oscillations during training. Furthermore, decreases in left LC contrast were associated with decreased expression of CREB-associated gene transcripts. On the contrary, there were no effects of biofeedback on LC contrast among older participants in the experimental group. These findings provide novel evidence that in younger adults, HRV biofeedback involving slow, paced breathing can decrease both LC contrast and sympathetic nervous system signaling.

Mediating effects of heart rate variability on the association between chronic stress, cardiorespiratory fitness and working memory maintenance

Young adulthood is a demanding developmental stage during which an individual is required to learn to adequately respond to physical and psychosocial stressors (Malter Cohen et al., 2013). High degrees of chronic stress have been shown to have detrimental effects on physical and mental health outcomes in young adults, accompanied by decreases in academic achievement and subjective well-being (Bayram & Bilgel, 2008; Malter Cohen et al., 2013). While effects of acute stress on neurocognitive functioning have been examined, documentation on effects of prolonged stress exposure on working memory is scarce. While chronic stress may impair working memory, empirical evidence supports the assumption that exercise targeting cardiorespiratory fitness has the potential to buffer harmful effects of stress on working memory performance (Loprinzi & Frith, 2019). According to the Neurovisceral Integration Theory, shared neurophysiological areas are involved in cardiac autonomic control as well as the modulation of attentional and emotional regulatory processing (Forte et al., 2019). Therefore, heart rate-variability (HRV) may be a physiological correlate mediating the association between chronic stress, cardiorespiratory fitness and working memory maintenance.
 The present study investigated the mediating role of resting heart rate-variability on the association between chronic stress, cardiorespiratory fitness and working memory maintenance in young healthy adults.
 Working memory maintenance was assessed in N = 115 healthy adults (48% female) aged 18 to 35 years (M = 24.1, SD = 3.8) using a modified version of the Sternberg task with low (3 items) and high cognitive load (6 items). Additionally, the Åstrand test was conducted on a bicycle ergometer to estimate maximal oxygen consumption (VO2max). Resting HRV was recorded using electrocardiography. The LF/HF ratio was extracted for mediation analyses.
 Path analysis revealed a significant association between cardiorespiratory fitness and accuracy on high cognitive load trials, but not on trials with low cognitive load. Levels of perceived chronic stress showed a trend for a positive association with working memory maintenance, independently of cognitive load. The pattern of results remained unchanged after introduction of HRV as a mediator.
 Results indicate that despite young adulthood being characterized by peak cognitive performance, cardiorespiratory fitness influences working memory maintenance. The lack of mediating effects of HRV, indicates that this association cannot be explained by vagal influences on memory processing driven by the autonomic nervous system. As working memory is crucial for performance in many real-life domains, such as workplace and learning environments in general maintenance and promotion of cardiorespiratory fitness is encouraged.
 References
 Bayram, N., & Bilgel, N. (2008). The prevalence and socio-demographic correlations of depression, anxiety and stress among a group of university students. Social Psychiatry and Psychiatric Epidemiology, 43(8), 667-672. https://doi.org/10.1007/s00127-008-0345-x
 Forte, G., Favieri, F., & Casagrande, M. (2019). Heart rate variability and cognitive function: A systematic review [Mini Review]. Frontiers in Neuroscience, 13, Article 710. https://doi.org/10.3389/fnins.2019.00710
 Loprinzi, P. D., & Frith, E. (2019). Protective and therapeutic effects of exercise on stress-induced memory impairment. Journal of Physiological Sciences, 69(1), 1-12. https://doi.org/10.1007/s12576-018-0638-0
 Malter Cohen, M., Tottenham, N., & Casey, B. J. (2013). Translational developmental studies of stress on brain and behavior: Implications for adolescent mental health and illness? Neuroscience, 249, 53-62. https://doi.org/https://doi.org/10.1016/j.neuroscience.2013.01.023

Changes in Medial Prefrontal Cortex Mediate Effects of Heart Rate Variability Biofeedback on Positive Emotional Memory Biases

Previous research suggests that implicit automatic emotion regulation relies on the medial prefrontal cortex (mPFC). However, most of the human studies supporting this hypothesis have been correlational in nature. In the current study, we examine how changes in mPFC-left amygdala functional connectivity relate to emotional memory biases. In a randomized clinical trial examining the effects of heart rate variability (HRV) biofeedback on brain mechanisms of emotion regulation, we randomly assigned participants to increase or decrease heart rate oscillations while receiving biofeedback. After several weeks of daily biofeedback sessions, younger and older participants completed an emotional picture memory task involving encoding, recall, and recognition phases as an additional measure in this clinical trial. Participants assigned to increase HRV (Osc+) (n = 84) showed a relatively higher rate of false alarms for positive than negative images than participants assigned to decrease HRV (Osc−) (n = 81). Osc+ participants also recalled relatively more positive compared with negative items than Osc− participants, but this difference was not significant. However, a summary bias score reflecting positive emotional memory bias across recall and recognition was significantly higher in the Osc+ than Osc− condition. As previously reported, the Osc+ manipulation increased left amygdala-mPFC resting-state functional connectivity significantly more than the Osc− manipulation. This increased functional connectivity significantly mediated the effects of the Osc+ condition on emotional bias. These findings suggest that, by increasing mPFC coordination of emotion-related circuits, daily practice increasing heart rate oscillations can increase implicit emotion regulation.

Regulatory Emotional Self-Efficacy Buffers the Effect of Heart Rate Variability on Functional Capacity in Older Adults With Chronic Low Back Pain.

IntroductionChronic low back pain is one of the leading causes of disability globally among older adults. Prevailing research suggests that autonomic dysregulation places individuals at increased risk for chronic pain. This study examines the moderating role of emotional self-efficacy (ESE) on the relationship between heart rate variability (HRV) and pain related-outcomes, including movement-evoked pain (MEP) and physical functioning.MethodsIn a secondary analysis of the Adaptability and Resilience in Aging Adults (ARIAA) study, a total of 58 adults (aged 60 and older) with chronic low back pain (cLBP) completed the PROMIS self-efficacy for managing emotions questionnaire and the 6-minute walk test (6 MWT) to assess functional capacity and MEP. Heart rate variability, indexed by the frequency domain, was assessed for 5 min during rest.ResultsFor pain-related outcomes, having a lower body mass index (p = 0.03) was associated with better functional capacity on the 6MWT, while higher education level (p = 0.01) and less pain duration (p = 0.00) were correlated with lower MEP. After controlling for sex, age, and body mass index, an increase in low-frequency HRV (LF-HRV) was associated with poorer physical functioning among individuals low in ESE (b = −0.12 p = 0.03). No significant moderation effects were observed for MEP.ConclusionOur results bring attention to the degree to which ESE influences the relationship between LF-HRV and physical functioning. Interventions that enhance adaptive psychological processes such as ESE may dampen ANS dysregulation and mitigate risk for adverse pain outcomes among older adults with cLBP.

The Effects of Heart Rate Variability (HRV) Biofeedback on HRV Reactivity and Recovery During and After Anger Recall Task for Patients with Coronary Artery Disease.

Patients with coronary artery disease (CAD) often experience anger events before cardiovascular events. Anger is a psychological risk factor and causes underlying psychophysiological mechanisms to lose balance of the autonomic nervous system (ANS). The heart rate variability (HRV) was the common index for ANS regulation. It has been confirmed that heart rate variability biofeedback (HRV-BF) restored ANS balance in patients with CAD during the resting state. However, the effects of HRV-BF during and after the anger event remain unknown. This study aimed to examine the effects of HRV-BF on ANS reactivity and recovery during the anger recall task in patients with CAD. This study was a randomized control trial with a wait-list control group design, with forty patients in the HRV-BF group (for six sessions) and 44 patients in the control group. All patients received five stages of an anger recall task, including baseline, neutral recall task, neutral recovery, anger recall task, and anger recovery. HRV reactivity in the HRV-BF group at the post-test was lower than that in the control group. HRV recovery at the post-test in the HRV-BF group was higher than that in the control group. The HRV-BF reduced ANS reactivity during anger events and increased ANS recovery after anger events for CAD patients. The possible mechanisms of HRV-BF may increase total HRV, ANS regulation, and baroreflex activation at anger events for patients with CAD, and may be a suitable program for cardiac rehabilitation.

Respiratory Sinus Arrhythmia Mediates the Relation Between "Specific Math Anxiety" and Arithmetic Speed.

There is a growing consensus that math anxiety highly correlates with trait anxiety and that the emotional component elicited by math anxiety affects math performance. Yet few studies have examined the impact of “specific math anxiety” (high math anxiety and low other kinds of anxiety) on math performance and the underlying physiological and affective mechanism. The present study examines the mediation effect of heart rate variability—an affective measurement indexed by respiratory sinus arrhythmia (RSA)—in the relationship between specific math anxiety and arithmetic speed. A total of 386 junior high school students completed a self-reported questionnaire to measure their anxiety level. Among this sample, 29 individuals with specific math anxiety (high math anxiety and low reading and trait anxiety), 29 with specific reading anxiety (high reading anxiety and low math and trait anxiety), 24 with specific trait anxiety (high trait anxiety and low math and reading anxiety), and 22 controls (low math, trait and reading anxiety) were selected to participate in an arithmetic task and a reading task while RSA was recorded when they performed the tasks. Results revealed that individuals with specific math anxiety showed lower RSA and longer reaction time than the other three groups in the arithmetic task. Regression and mediation analyses further revealed that RSA mediated the relation between specific math anxiety and arithmetic speed. The present study provides the first account of evidence for the affective hypothesis of specific math anxiety and suggests that affective responses may be an important mechanism underlying the detrimental effect of specific math anxiety on math performance.

The interactive effects of heart rate variability and mindfulness on indicators of well-being in healthcare professionals' daily working life

ObjectiveHeart rate variability (HRV) and mindfulness have been described as correlates of self-regulation and well-being. The goal of the present study was to investigate their interactions from a within-person perspective in the context of work. MethodsApplying an ambulatory assessment approach, we studied 89 healthcare professionals across two to four work shifts. Self-reports of momentary job demands, mindfulness, and well-being (as indicated by emotional exhaustion, relaxation, and contentment) were provided three to four times a day via smartphone questionnaires. Electrocardiogram and activity sensors continuously recorded data from the beginning to the end of the shifts. Multilevel models based on 937 measurements were built for emotional exhaustion, relaxation, and contentment. ResultsAfter controlling for covariates, including bodily movement, shift, and job demands, short-term HRV was marginally significantly related to decreased emotional exhaustion and significantly related to increased relaxation. State mindfulness was significantly related to decreased emotional exhaustion, and increased relaxation and contentment. Furthermore, HRV and mindfulness significantly interacted such that emotional exhaustion was lowest and relaxation was highest when both HRV and mindfulness were high. ConclusionsTogether, the findings provide insights into the use of HRV and mindfulness as indexes of psychophysiological regulatory resources that seemingly intensify their respective beneficial effects on the daily well-being of employees.

Ethnic and sex differences in the longitudinal association between heart rate variability and blood pressure

Purpose Elevated blood pressure is a risk factor for increased cardiovascular morbidity and mortality. Decreased vagally-mediated heart rate variability has previously been prospectively linked with increased blood pressure; however, to date, no such prospective data exist regarding this relationship among Blacks. Materials and methods We examined this association in 387 normotensive young adults (mean age, 23 years, 52% female, 54% Black) who participated in two laboratory evaluations spanning approximately six years. Blood pressure was measured at both timepoints with a non-invasive oscillometric device and heart rate variability was assessed via bio-impedance. Results In the total sample, heart rate variability significantly predicted systolic (p = .022) and diastolic (p < .001) blood pressure increases six years into the future. However, this pattern varied as a function of ethnicity and sex with the effect of heart rate variability on Time 2 systolic blood pressure only significant among White males (p = .007). Heart rate variability was also predictive of Time 2 diastolic blood pressure in White males (p = .038) as well as among both White (p = .032) and Black (p = .015) females, but was not related to blood pressure among Black males. Conclusion We report for the first time significant ethnic and sex differences in the prospective relationship between heart rate variability and blood pressure change. These findings may give clues as to the underlying mechanisms that are involved in the well-known health disparities in blood pressure and hypertension-related cardiovascular diseases.

Stability analysis on the effects of heart rate variability and premature activation of atrial ECG dynamics using ARMAX model.

The cellular action potential of cardiac muscles generates Electrocardiogram (ECG) signals. Disturbances in cardiac cells are determined by analyzing the stability of ECG intervals. The PTa Interval (PTaI) of ECG represents the atrial Action Potential Duration (APD) and the evaluation of the causes of PTaI instability can predict the onset of arrhythmia. This study developed an Autoregressive Moving Average with Exogenous Input (ARMAX) model to explore the roles of Heart Rate Variability (HRV) and Premature Activation (PA) in PTaI dynamics using PTaI and PP Interval (PPI) as exogenous inputs. Minute ECG signals were collected from twenty Normal Sinus Rhythm (NSR) and ten Atrial Tachycardia (AT) volunteers. The EDAN PC ECG system was used in the Modified Limb Lead (MLL)configuration to evaluate instability. The instabilities of PTaI were found at the minimum model orders (Amin) of 10 and 11, in the NSR and AT groups, respectively. In the NSR group, the predominant reason for PTaI instability was HRV, whereas among AT patients, it was largely due to PA that preceded the onset of AT. The proposed model showed better prediction of PTaI with minimum Mean Square Error(MSE) between the measured and predicted PTa Intervals (PTaIs). The factor that led to PTaI instability in AT patients was found to be different from that of the NSR group. The frequency of PA (fPA) was found to contribute more in the AT than the NSR group. The developed ARMAX model was better in predicting instability of atrial ECG dynamics in both groups than other autoregressive models currently in use.

Design of Pulse Oximeter Solution for Conscious Rodents

Neuromodulation can be used to control organ function through exogenous augmentation of neural activity via targeted delivery of an electrical stimulus. Recently, neuromodulation has been a topic of investigation to treat many illnesses and conditions including Parkinson’s disease, epilepsy, obesity, chronic pain, type 1 diabetes, and hypertension. During neuromodulatory treatments, it is important to measure both the physiological response of the target system as well as any off-target systems that may be engaged from the delivered stimulus. Stimulation of the vagus nerve, a common target of neuromodulatory therapies, causes a vasovagal response which results in decreased cardiac rate and arteriolar dilatation. It is possible to measure these physiological parameters in anesthetized rats, but it is a challenge in conscious, moving rats because of motion artifact introduced to the sensors. By creating a noninvasive, stabilized pulse oximeter that measures the blood oxygenation waveform, one can analyze the heart rate in awake behaving animals. This study reports the design of a heart rate monitor used to monitor effects of heart rate variability during neuromodulation experiments. Design of this device included testing different sensors, methods of attaching to the rodent, microcontrollers, and wireless communication modules.

The effect of heart rate variability on blood pressure is augmented in spinal cord injury and is unaltered by exercise training.

To define differences in heart rate and blood pressure variability (HRV/BPV) after spinal cord injury (SCI) compared with uninjured controls, and to determine whether variabilities are impacted by whole-body exercise after SCI. Individuals with SCI (n = 40), aged 18-40, and uninjured age/sex-matched controls (n = 22) had HRV and BPV determined during supine paced (0.25Hz) breathing. Spectral and cross-spectral values were derived for fluctuations at low (LF 0.05-0.15Hz) and high (HF 0.20-0.30Hz) frequencies. Thirty-two individuals with SCI further underwent either 6months of whole-body exercise training (n = 17) or a control intervention (n = 15). Individuals with SCI had injuries graded A-C in severity, neurological levels of injury C1-T10. LF and HF HRV and LF BPV were significantly lower in individuals with SCI (p = 0.008-0.002), though HF BPV was similar. The LF cross-spectrum demonstrated similar phase and gain relationships between groups. The HF phase relationship between pressure and heart rate differed markedly: individuals with SCI demonstrated a -11.7 ± 3.4° phase lag (241 ± 70ms feedback mechanism of pressure into heart rate), whereas uninjured controls demonstrated a +21.5 ± 10.8° phase lead (443 ± 224ms feedforward mechanism of heart rate into pressure, p = 0.007). Whole-body exercise increased mean VO2peak by 2.09ml/kg, whereas HRV, BPV, and their cross-spectral relationships were not significantly altered relative to the control intervention after SCI. After SCI, marked frequency-specific differences exist in the relationship between heart rate and blood pressure variabilities. The high-frequency cross-spectral relationship indicates that a feedback mechanism of blood pressure into heart rate may predominate in this range.

Reducing suicidal ideation by biofeedback-guided respiration – heart rate coherence

Background Effectiveness of heart rate variability (HRV) biofeedback is dependent on the relationship between the measured respiratory-heart rate coherence (C HR) and the resonant frequency (RFB) breathing. C HR is driven by the central autonomic network which consists of the interplay between the components of the autonomic nervous system, brainstem modulatory nuclei and cortical function. The extent to which heart rate is in coherence with respiratory frequency and the function of the central autonomic network in major depressive disorder (MDD) and suicidal ideation (SI) has not been investigated. Method: Sixty-one patients provided informed consent to participate and were divided into no MDD (CONT), MDD and an MDD plus SI (MDDSI) group. HRV activity was determined by multi lag tone-entropy (T-E) and respiratory-C HR at rest was characterized by the relationship between respiratory rate and heart rate. Results: CONT had the highest entropy compared to the MDDSI group, which had the lowest entropy and highest tone (p < 0.05). Autonomic parasympathetic function was also significantly lower in the MDDSI compared to the MDD group (p < 0.05). C HR indicated a significant phase desynchronization (decrease in coherence) between MDDSI, MDD and CONT (p < 0.05), with MDDSI having the lowest coherence and CONT the highest. Conclusion: T-E analysis indicated that HRV was significantly different in patients with SI. C HR as measured by our proposed synchronization index provides a novel feature to adapt HRV biofeedback to individual psychiatric profiles and may provide better clinical outcomes for this patient group.

P3833Low heart rate variability is associated with future arrhythmic events in hypertension

Abstract Background/Introduction Cardiac autonomic dysfunction and target organ damage are associated with increased cardiovascular mortality and arrhythmias. Purpose The aim of the study was to investigate the effect of heart rate variability (HRV) and markers of target organ damage in the prognosis of future arrhythmic events. Methods We studied 292 untreated at baseline hypertensives (mean age 53±13, 153 males). Cardiac autonomic function was evaluated by analysis of short-term HRV measures over 24-h using 24-h ambulatory blood pressure monitoring and the standard deviation of the measurements. Echocardiography was also performed and left ventricular mass index (LVMI) was estimated with the Demereux formula. Aortic stiffness was assessed with carotid-femoral pulse wave velocity (cfPWV) and wave reflections with aortic augmentation index corrected for heart rate (Alx@75). Patients were followed up for a median period of 13 years. The primary endpoint was a composite of atrial/ventricular tachycardias, symptomatic multiple premature ventricular contractions, second and third-degree heart blocks and pacemaker/defibrillator placement. Results In comparison without events, patients with the primary endpoint (n=37, 13%) had lower 24-h daytime HRV (9.6 beats per minute vs. 11.1 beats per minute, p=0.005), higher systolic blood pressure (168 mmHg vs. 163 mmHg, p=0.003), higher cfPWV (8.4 m/s vs. 7.7 m/s, p=0.005), higher LVMI (133 g/m2 vs. 122 g/m2, p=0.002) and higher AIx@75 (29.0% vs. 26.3%, p=0.043). In further analysis, receiver operating characteristic (ROC) curves were generated to evaluate the ability of HRV, cfPWV, LVMI and AIx@75 to discriminate subjects with arrhythmic events. The area under the curve (AUC) and 95% CIs of the ROC curves were AUC=0.35 (95% CI: 0.26–0.44, p=0.003) for HRV, AUC=0.64 (95% CI: 0.54–0.73, P&lt;0.006) for cfPWV, AUC=0.67 (95% CI: 0.58–0.75, P=0.001) for LVMI and AUC=0.55 (95% CI: 0.47–0.64, P=0.298) for AIx@75 (Figure). In Cox regression analysis, only HRV was associated with increased risk of arrhythmic events (Hazard ratio per 1 unit =0.87, 95% Confidence intervals 0.76 to 0.995, p=0.043) when adjusted for age, gender, cfPWV, LVMI and AIx@75. ROC curves of HRV &amp; target organ damage Conclusions Low heart rate variability is associated with increased risk of future arrhythmic events suggesting an early sympathovagal imbalance that could lead to future events in hypertension.

Effect of Heart Rate Variability on the Association Between the Apnea-Hypopnea Index and Cerebral Small Vessel Disease.

Background and Purpose- The apnea-hypopnea index (AHI) is associated with cerebral small vessel disease (cSVD), but pathogenesis of this association is elusive. We aimed to assess the effect of nighttime heart rate variability (HRV)-as a proxy of sympathetic upregulation-on the aforementioned association. Methods- Atahualpa residents aged ≥60 years undergoing brain magnetic resonance imaging, polysomnography, and 24-hour Holter monitoring (N=176) were included. The presence of moderate-to-severe white matter hyperintensities, deep cerebral microbleeds, lacunar infarcts, and >10 enlarged basal ganglia perivascular spaces were added for estimating the cSVD score. Interaction models were fitted to assess the effect modification of nighttime HRV in the association between the AHI and the cSVD score, and mediation analysis was utilized to assess the proportion of total effect by nighttime HRV on this association. Results- Generalized linear models showed a significant association between the AHI and the cSVD score (P=0.025), as well as a significant inverse association between nighttime HRV and the cSVD score (P=0.002), but no association between daytime HRV and the cSVD score (P=0.097). Interaction models showed a significant interaction of nighttime HRV on the association between AHI and the cSVD score (P=0.001), and mediation analysis found that the percent of total effect between AHI and cSVD score mediated by HRV was 30.8%. Predictive marginal means of the cSVD score were highly significant when the 10th percentile of nighttime HRV was compared across categories of 10th and 90th percentiles of the AHI (cSVD score margins, 0.61 [95% CI, 0.37-0.86] versus 1.67 [95% CI, 1.26-2.09]). Contour plots showed the effect of nighttime (but not daytime) HRV on the association between AHI and the cSVD score. Conclusions- This study shows an important effect of nighttime HRV on the association between the AHI and the cSVD score and provides further support for the role of sympathetic overactivity on this association.

Classification of congestive heart failure with different New York Heart Association functional classes based on heart rate variability indices and machine learning

AbstractThis study aims to evaluate the effect of heart rate variability (HRV) indices on the New York Heart Association (NYHA) classification of patients with congestive heart failure and to test the effectiveness of different machine learning algorithms. Twenty‐nine long‐term RR interval recordings from subjects (aged 34 to 79) with congestive heart failure (NYHA classes I, II, and III) in MIT‐BIH Database were studied. We firstly removed the unreasonable RR intervals and segment the RR recordings with a 300‐RR interval length window. Then the multiple HRV indexes were calculated for each RR segment. Support vector machine (SVM) and classification and regression tree (CART) methods were then separately used to distinguish patients with different NYHA classes based on the selected HRV indices. Receiver operating characteristic curve analysis was finally employed as the evaluation indicator to compare the performance of the two classifiers. The SVM classifier achieved accuracy, sensitivity, and specificity of 84.0%, 71.2%, and 83.4%, respectively, whereas the CART classifier achieved 81.4%, 66.5%, and 81.6%, respectively. The area under the curve of receiver operating characteristic for the two classifiers was 86.4% and 84.7%, respectively. It is possible for accurately classifying the NYHA functional classes I, II, and III when using the combination of HRV indices and machine learning algorithms. The SVM classifier performed better in classification than the CART classifier using the same HRV indices.

The moderating effect of heart rate variability on the relationship between alpha asymmetry and depressive symptoms

Electroencephalographic (EEG) research has suggested relatively reduced brain activity in the left frontal and right posterior region trait-markers of depression. However, inconsistent results have been reported. Based on previous studies reporting the heart rate variability (HRV) as an index of emotional regulation, this study makes a novel investigation of the role of heart rate variability (HRV) as a moderator in the relationship between frontal and parietal alpha asymmetry and depression. Resting EEG (eyes open) was recorded in 38 patients with MDD and 34 healthy subjects. Frontal and parietal alpha asymmetries were calculated at total (8–12 Hz), high (10–12 Hz), and low (8–10 Hz) alpha frequency bands. Three vagally mediated HRV (vmHRV) components (LF, HF, and the LF/HF ratio) were calculated in the frequency domain. Relatively greater right parietal alpha activity significantly predicted the severity of depression only when HF was low (or the LF/HF ratio was high) at low alpha frequency band. The interaction effect of parietal alpha asymmetry and vmHRV remained significant after including anxiety score as a covariate. No moderation effect of vmHRV was found for frontal sites and other frequency bands, as well as healthy subjects. These findings suggest that vmHRV moderates the association between parietal alpha asymmetry at low frequency band and depression for MDD patients. We suggest that the interaction between parietal alpha asymmetry and vmHRV may be a biomarker of MDD.

Endurance Running Training Individually Guided by HRV in Untrained Women.

da Silva, DF, Ferraro, ZM, Adamo, KB, and Machado, FA. Endurance running training individually guided by HRV in untrained women. J Strength Cond Res 33(3): 736-746, 2019-The aim of this study was to analyze the effects of heart rate variability (HRV)-guided training compared with a standardized prescription on (a) time to complete 5-km running performance (t5km), (b) peak treadmill running speed (Vpeak) and its time limit (tlim at Vpeak), and (c) autonomic cardiac modulation (i.e., parasympathetic activity and recovery) in untrained women. Additionally, we correlated changes in t5km with changes in Vpeak, tlim at Vpeak and autonomic cardiac modulation. Thirty-six untrained women were divided into a HRV-guided training group (HRVG) and a control group (CG). The CG followed a predefined program, alternating moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). The determination of MICT or HIIT was based on the pretraining HRV for HRVG. MICT was performed if HRV was <mean - 1 SD of previous measures. Otherwise, HIIT was prescribed. The t5km, Vpeak, tlim at Vpeak, parasympathetic activity (i.e., rMSSD) and parasympathetic reactivation (i.e., HRR) were measured before and after the training period. The t5km decreased to a greater magnitude in the HRVG (-17.5 ± 5.6% vs. -14 ± 4.7%; Effect Size (ES) between-group difference = moderate). rMSSD and tlim at Vpeak only improved in HRVG (+23.3 ± 27.8% and +23.6 ± 31.9%, respectively). The HRVG experienced greater improvements in Vpeak and HRR (Vpeak: 10 ± 7.3% vs. 8.2 ± 4.7%; HRR: 19.1 ± 28.1% vs. 12.6 ± 12.9%; ES between-group difference = small). Although HRVG performed less MICT than CG, the volume of MICT was negatively related to changes in t5km. Vpeak changes were highly correlated with t5km changes. The greater improvements in HRVG for t5km and autonomic modulation reinforce the potential application of this tool.