Heart Rate Fluctuations Research Articles

Cardio‐autonomic control during exercise and risk for incident delirium

AbstractBackgroundDelirium is associated with increased risk for Alzheimer’s disease (AD) and mortality; it is characterized by acute confusion commonly after stressors of illness during hospitalization. Integration between the heart and brain via the autonomic nervous system, or cardio‐autonomic control (CAC) is thought to be potentially protective during such stressors. Related to CAC, heart rate (HR) fluctuations display fractal correlations (similar temporal autocorrelation across different time scales) that reflect a dynamic interplay between sympathetic and vagal outflows, where disruption is thought to contribute to neuronal damage. We hypothesized that fractal correlations in HR fluctuations can serve as a novel physiological biomarker for predicting incident delirium.MethodWe derived fractal correlations (α) using ECG data from 37,978 participants (mean age 57.4) free from delirium and AD within the UK Biobank who underwent a 7‐minute stationary bike stress test between 2009‐2010, and had ≥1 inpatient hospitalization episode through to August 2020. Cox proportional hazards models were used to examine the association between α and incident delirium. We adjusted for demographics, physical activity levels, BMI, smoking, alcohol, cholesterol, diabetes, hypertension, ischemic heart disease, stroke, as well as test‐specific peak exercise load and mean heart rate achieved.ResultIncident delirium was newly diagnosed in 247 cases (6.5/1,000) during a median follow‐up time of 8.1 years (SD: 2.0, range: 0.2‐10.2) following ECG assessment. α showed a normal distribution with mean of 1.27±0.3 (SD). Negative association between α and incident delirium was observed. The fully adjusted hazard ratio was 1.26 (95% confidence interval: 1.10‐1.45; p=0.001) for each 1‐SD decrease in α. Putting this into context, a subject with a lower α at the 10thpercentile (vs. 90th) showed a 59% increased risk of developing incident delirium, equivalent to the additional risk of being 5‐years older or a current smoker in this cohort.ConclusionFractal correlation of heartbeat fluctuations during an exercise ECG recording was independently associated with incident delirium, and may be a hidden measure of brain‐heart resilience. As this cohort ages, future work will be able to answer the crucial question of whether this is a shared marker of vulnerability between delirium and AD.

Is there an association between socioeconomic status and the degree of diurnal variation in heart rate?

BackgroundDisruption in circadian rhythms is associated with cardiovascular disease and may play a role in socioeconomic differences in cardiovascular disease prevalence. However, it is unclear whether low SES is associated with a lower diurnal rhythm in autonomic activity markers. We investigated the association between SES and the amplitude of the daily fluctuation of heart rate. MethodsWe included data of 450 participants of a HELIUS sub-study in Amsterdam, the Netherlands. Participants wore an Actiheart monitor (CamNtech), a chest-worn monitor which measures heart rate every 15 s for several days. Cosinor analysis was performed on the time series of heart rate within each participant. We analyzed the association between the cosinor parameters (amplitude, midline and peak time of the diurnal HR rhythm) and SES indicators (education, occupational class and a proxy of income) in multivariate linear regression models, adjusting for age, sex and ethnicity. ResultsThere was a clear diurnal rhythm in the average heart rates, with a peak between noon and 18:00 and a trough between 04:00 and 06:00. This rhythm was present for all categories of education, occupation and income proxy. The estimates for the cosinor parameters did not differ consistently and significantly between categories of education, occupation or income proxy. ConclusionsWe did not find any consistent evidence to support our hypothesis of a diminished amplitude in the diurnal variation of heart rate in individuals with lower SES. Future studies should explore SES differences in the diurnal variation in markers of autonomic activity other than heart rate.

Does COVID‐19 influence the sympathetic regulation of blood pressure?

Does COVID‐19 influence the sympathetic regulation of blood pressure?

ECG Authentication Based on Non-Linear Normalization under Various Physiological Conditions.

The development and use of wearable devices require high levels of security and have sparked interest in biometric authentication research. Among the available approaches, electrocardiogram (ECG) technology is attracting attention because of its strengths in spoofing. However, morphological changes of ECG, which are affected by physical and psychological factors, can make authentication difficult. In this paper, we propose authentication using non-linear normalization of ECG beats that is robust to changes in ECG waveforms according to heart rate fluctuations in various daily activities. We performed a non-linear normalization method through the analysis of ECG alongside heart rate, evaluating similarities and authenticating the performance of our new method compared to existing methods. Compared with beats before normalization, the average similarity of the proposed method increased 23.7% in the resting state and 43% in the non-resting state. After learning in the resting state, authentication performance reached 99.05% accuracy for the resting state and 88.14% for the non-resting state. The proposed method can be applicable to an ECG-based authentication system under various physiological conditions.

Dissecting the Roles of the Autonomic Nervous System and Physical Activity on Circadian Heart Rate Fluctuations in Mice.

Heart rate (HR) and blood pressure as well as adverse cardiovascular events show clear circadian patterns, which are linked to interdependent daily variations in physical activity and cardiac autonomic nerve system (ANS) activity. We set out to assess the relative contributions of the ANS (alone) and physical activity to circadian HR fluctuations. To do so, we measured HR (beats per minute, bpm) in mice that were either immobilized using isoflurane anesthesia or free-moving. Nonlinear fits of HR data to sine functions revealed that anesthetized mice display brisk circadian HR fluctuations with amplitudes of 47.1±7.4bpm with the highest HRs in middle of the dark (active) period (ZT 18: 589±46bpm) and lowest HRs in the middle of the light (rest) period (ZT 6: 497±54bpm). The circadian HR fluctuations were reduced by ~70% following blockade of cardiac parasympathetic nervous activity (PNA) with atropine while declining by <15% following cardiac sympathetic nerve activity (SNA) blockade with propranolol. Small HR fluctuation amplitudes (11.6±5.9bpm) remained after complete cardiac ANS blockade. Remarkably, circadian HR fluctuation amplitudes in freely moving, telemetrized mice were only ~32% larger than in anesthetized mice. However, after gaining access to running wheels for 1week, circadian HR fluctuations increase to 102.9±12.1bpm and this is linked directly to increased O2 consumption during running. We conclude that, independent of physical activity, the ANS is a major determinant of circadian HR variations with PNA playing a dominant role compared to SNA. The effects of physical activity to the daily HR variations are remarkably small unless mice get access to running wheels.

Physiological and Biomechanical Responses to Cross-Country Skiing in Varying Terrain: Low- vs. High-Intensity.

The purposes of our study were to investigate the physiological and biomechanical responses to low-intensity (LI) and high-intensity (HI) roller ski skating on varying terrain and compare these responses between training intensities. Nine elite male skiers performed treadmill roller skiing consisting of two 21 min sessions (7 × 3 min laps) at LI and HI with the same set inclines and intensity-dependent speeds (LI/HI: distance: 5.8/7.5 km, average speed: 16.7/21.3 km/h). Physiological and biomechanical variables were measured continuously, and each movement cycle and sub-technique employed were detected and classified with a machine learning model. Both the LI and HI sessions induced large terrain-dependent fluctuations (relative to the maximal levels) in heart rate (HR, 17.7 vs. 12.2%-points), oxygen uptake (, 33.0 vs. 31.7%-points), and muscle oxygen saturation in the triceps brachii (23.9 vs. 33.4%-points) and vastus lateralis (12.6 vs. 24.3%-points). A sub-technique dependency in relative power contribution from poles and skis exhibited a time-dependent shift from Lap 1 to Lap 7 toward gradually more ski power (6.6 vs. 7.8%-points, both p < 0.01). The terrain-dependent fluctuations did not differ between LI and HI for (p = 0.50), whereas HR fluctuated less (p < 0.01) and displayed a time-dependent increase from Lap 2 to Lap 7 (7.8%-points, p > 0.01) during HI. Oxygen saturation shifted 2.4% points more for legs than arms from LI to HI (p > 0.05) and regarding sub-technique, 14.7% points more G3 on behalf of G2 was employed on the steepest uphill during HI (p < 0.05). Within all sub-techniques, cycle length increased two to three times more than cycle rate from LI to HI in the same terrains, while the corresponding poling time decreased more than ski contact time (all p > 0.05). In sum, both LI and HI cross-country (XC) skiing on varying terrain induce large terrain-dependent physiological and biomechanical fluctuations, similar to the patterns found during XC skiing competitions. The primary differences between training intensities were the time-dependent increase in HR, reduced relative oxygen saturation in the legs compared to the arms, and greater use of G3 on steep uphill terrain during HI training, whereas sub-technique selection, cycle rate, and pole vs. ski power distribution were similar across intensities on flat and moderately uphill terrain.

Cardiology meets neurology: Clinical presentation and management of patients with primary neurogenic disorders and orthostatic intolerance

Patients with primary neurogenic disorders such as pure autonomic failure or multiple system atrophy may present first with cardiocirculatory symptoms such as orthostatic intolerance or fluctuations in heart rate with symptomatic tachycardia. It is therefore clinically important to identify such patients since circulatory manifestations are only one of a series of symptoms resulting from autonomic dysfunction in various organ systems. These patients need a multimodal diagnostic and therapeutic approach and should undergo extensive evaluation in a specialized autonomic nervous system (ANS) outpatient unit.

Sleep apnea screening based on Photoplethysmography data from wearable bracelets using an information-based similarity approach

Background and ObjectiveSleep apnea (SA) is a common sleep disorder in daily life and is also an aggravating factor for various diseases. Having the potential to replace traditional but complicated diagnostic equipment, portable medical devices are receiving increasing attention, and thus, the demand for supporting algorithms is growing. This study aims to identify SA with wearable devices. MethodsStatic information-based similarity (sIBS) and dynamic information-based similarity (dIBS) were proposed to analyze short-term fluctuations in heart rate (HR) with wearable devices. This study included overnight photoplethysmography (PPG) signals from 92 subjects obtained from wearable bracelets. ResultsThe results showed that sIBS achieved the highest correlation coefficient with the apnea-hypopnea index (R=-0.653, p=0). dIBS showed a good balance in sensitivity and specificity (75.0% and 72.1%, respectively). Combining sIBS and dIBS with other classical time-frequency domain indices could simultaneously achieve good accuracy and balance (84.7% accuracy, 76.7% sensitivity and 89.6% specificity). ConclusionsThis research showed that both classic time-frequency domain indices and IBS indices changed significantly only in the severe SA group. This novel method could serve as an effective way to assess SA and provide new insight into its pathophysiology.

Enhanced detection of abnormalities in heart rate variability and dynamics by 7-day continuous ECG monitoring.

BackgroundThe analysis of heart rate variability (HRV) and heart rate (HR) dynamics by Holter ECG has been standardized to 24 hs, but longer‐term continuous ECG monitoring has become available in clinical practice. We investigated the effects of long‐term ECG on the assessment of HRV and HR dynamics.MethodsIntraweek variations in HRV and HR dynamics were analyzed in 107 outpatients with sinus rhythm. ECG was recorded continuously for 7 days with a flexible, codeless, waterproof sensor attached on the upper chest wall. Data were divided into seven 24‐h segments, and standard time‐ and frequency‐domain HRV and nonlinear HR dynamics indices were computed for each segment.ResultsThe intraweek coefficients of variance of HRV and HR dynamics indices ranged from 2.9% to 26.0% and were smaller for frequency‐domain than for time‐domain indices, and for indices reflecting slower HR fluctuations than faster fluctuations. The indices with large variance often showed transient abnormalities from day to day over 7 days, reducing the positive predictive accuracy of the 24‐h ECG for detecting persistent abnormalities over 7 days. Conversely, 7‐day ECG provided 2.3‐ to 6.5‐fold increase in sensitivity to detect persistent plus transient abnormalities compared with 24‐h ECG. It detected an average of 1.74 to 2.91 times as many abnormal indices as 24‐h ECG.ConclusionsLong‐term ECG monitoring increases the accuracy and sensitivity of detecting persistent and transient abnormalities in HRV and HR dynamics and allows discrimination between the two types of abnormalities. Whether this discrimination improves risk stratification deserves further studies.

Conscious processing of narrative stimuli synchronizes heart rate between individuals

Heart rate has natural fluctuations that are typically ascribed to autonomic function. Recent evidence suggests that conscious processing can affect the timing of the heartbeat. We hypothesized that heart rate is modulated by conscious processing and therefore dependent on attentional focus. To test this, we leverage the observation that neural processes synchronize between subjects by presenting an identical narrative stimulus. As predicted, we find significant inter-subject correlation of heart rate (ISC-HR) when subjects are presented with an auditory or audiovisual narrative. Consistent with our hypothesis, we find that ISC-HR is reduced when subjects are distracted from the narrative, and higher ISC-HR predicts better recall of the narrative. Finally, patients with disorders of consciousness have lower ISC-HR, as compared to healthy individuals. We conclude that heart rate fluctuations are partially driven by conscious processing, depend on attentional state, and may represent a simple metric to assess conscious state in unresponsive patients.

Physiological and motion signatures in static and time-varying functional connectivity and their subject identifiability.

Human brain connectivity yields significant potential as a noninvasive biomarker. Several studies have used fMRI-based connectivity fingerprinting to characterize individual patterns of brain activity. However, it is not clear whether these patterns mainly reflect neural activity or the effect of physiological and motion processes. To answer this question, we capitalize on a large data sample from the Human Connectome Project and rigorously investigate the contribution of the aforementioned processes on functional connectivity (FC) and time-varying FC, as well as their contribution to subject identifiability. We find that head motion, as well as heart rate and breathing fluctuations, induce artifactual connectivity within distinct resting-state networks and that they correlate with recurrent patterns in time-varying FC. Even though the spatiotemporal signatures of these processes yield above-chance levels in subject identifiability, removing their effects at the preprocessing stage improves identifiability, suggesting a neural component underpinning the inter-individual differences in connectivity.

The importance of thinking about Guillain-Barr\xe9 syndrome during the COVID-19 pandemic: a case with pure dysautonomic presentation

Guillain-Barré syndrome (GBS) is a peripheral nervous system disease caused by an immune-mediated inflammatory mechanism, usually triggered by a previous infectious process or vaccine; its typical presentation is a rapid and progressive bilateral limb hyposthenia, associated with sensory deficits and reduction or absence of osteotendinous reflexes. However, also autonomic nervous system can be involved with heart rate fluctuations, blood pressure instability, pupillary dysfunction, and urinary retention. Since the beginning of COVID-19 pandemic, GBS has been reported among neurological complications of SARS-CoV-2 infection, although etiopathological mechanisms still have to be clearly defined. We report the case of a 79-year-old man with multiple comorbidities, including diabetes, who was affected by SARS-CoV-2 interstitial pneumonia and developed dysautonomic symptoms after 10 days of hospitalization. A neurological evaluation was performed, and GBS was considered as a possible cause of the clinical manifestations. This hypothesis was confirmed by electrophysiological study and further supported, ex-juvantibus, by the satisfactory response to immunoglobulin treatment. In our opinion, this case of pure dysautonomic presentation of GBS in a SARS-CoV-2 positive patient is relevant because it suggests to consider GBS upon SARS-CoV-2 infection even if the symptoms have uncommon characteristics (e.g., pure vegetative manifestations) and if there are confounding factors which could lead to a misdiagnosis (e.g., old age, SARS-CoV-2 infection consequences and diabetes).

Asymmetric multiscale multifractal analysis (AMMA) of heart rate variability

Objective. The physiological activity of the heart is controlled and modulated mostly by the parasympathetic and sympathetic nervous systems. Heart rate variability (HRV) analysis is therefore used to observe fluctuations that reflect changes in the activity in these two branches. Knowing that acceleration and deceleration patterns in heart rate fluctuations are asymmetrically distributed, the ability to analyze HRV asymmetry was introduced into MMA. Approach. The new method is called asymmetric multiscale multifractal analysis (AMMA) and the analysis involved six groups: 36 healthy persons, 103 cases with aortic valve stenosis, 36 with hypertrophic cardiomyopathy, 32 with atrial fibrillation, 59 patients with coronary artery disease (CAD) and 13 with congestive heart failure. Main results. Analyzing the results obtained for the 6 groups of patients based on the AMMA method, i.e. comparing the Hurst surfaces for heart rate decelerations and accelerations, it was noticed that these surfaces differ significantly. And the differences occur in most groups for large fluctuations (multifractal parameter q > 0). In addition, a similarity was found for all groups for the AMMA Hurst surface for decelerations to the MMA Hurst surface—heart rate decelerations (lengthening of the RR intervals) appears to be the main factor determining the shape of the complete Hurst surface and so the multifractal properties of HRV. The differences between the groups, especially for CAD, hypertrophic cardiomyopathy and aortic valve stenosis, are more visible if the Hurst surfaces are analyzed separately for accelerations and decelerations. Significance. The AMMA results presented here may provide additional input for HRV analysis and create a new paradigm for future medical screening. Note that the HRV analysis using MMA (without distinguishing accelerations from decelerations) gave satisfactory screening statistics in our previous studies.

PHYSIOLOGICAL CHANGES DURING VAMAN PROCEDURE

Introduction: Vaman karma (therapeutic emesis) is one of the five Shodhan (purificatory) procedures mentioned in Ayurveda. It helps to expel vitiated Doshas from Urdhvabhaga i.e. mouth. A person performing Vaman regularly has very less chances of suffering from any disease. It is used as both a preventive and curative measure in healthy and diseased persons, respectively. So here in this study efforts have been made to observe the physiological changes occurring in various parameters like Pulse rate, Blood Pressure, Temperature, and oxygen saturation at different intervals, before the onset of Vega, just after 3-4 sec of completion of Vega, and during the whole of the Vaman procedure to understand the safety aspects of the procedure in patients and healthy volunteers. Methods: 20 subjects were selected irrespective of gender and religion from IPD of the Department of Panchakarma; they are first prepared with Deepan-Pachan followed by Snehan and Swedan before Vaman karma. Results: on keen ob- servation, it was found that there is a lot of variation in heart rate and sudden fluctuation in blood pressure at the time of vega during Vaman procedure. Conclusion: Vaman karma can be performed safely by anyone with proper assessment and examination of the patient without any complication. Keywords: Vaman, Panchakarma, physiological changes

Cardiology meets neurology: clinical presentation and management of patients with primary neurogenic disorders and orthostatic intolerance.

Patients with primary neurogenic disorders such as pure autonomic failure or multiple system atrophy may initially present with cardiocirculatory symptoms such as orthostatic intolerance or fluctuations in heart rate with symptomatic tachycardia. It is therefore clinically important to identify such patients since circulatory manifestations are only one of aseries of symptoms resulting from autonomic dysfunction in various organ systems. These patients require amultimodal diagnostic and therapeutic approach and should undergo extensive evaluation in aspecialized autonomic nervous system (ANS) outpatient unit. Based on aclinical case presentation, the current review summarizes the diagnostic and therapeutic approach to key cardiovascular symptoms of primary autonomic disorders and their neurological work-up in aspecialized autonomic function laboratory.

Association between respiratory and heart rate fluctuations and death occurrence in dying cancer patients: continuous measurement with a non-wearable monitor.

The present study aimed to explore the association between impending death and continual changes in respiratory and heart rates measured using a non-wearable monitor every minute for the final 2weeks of life in dying cancer patients. In this longitudinal study, we enrolled patients in a palliative care unit and continuously measured their respiratory and heart rates via a monitor and additionally captured their other vital signs and clinical status from medical records. A dataset was created comprising every 24-h data collected from every-minute raw data, including information from 240days prior to death from 24 patients (345,600 data); each patient's data were measured for 3-14days until death. After confirming the associations between the respiratory and heat rate values on the day of death (n = 24) or other days (2-14days before death, n = 216) and the mean, maximum, minimum, and variance of respiratory and heart rates every 24h by univariate analyses, we conducted a repeated-measures logistic regression analysis using a generalized estimating equation. Finally, the maximum respiratory rate and mean heart rate were significantly associated with death occurring within the following 3days (0-24h, 0-48h, and 0-72h), except for the maximum respiratory rate that occurs within 0-24h. The maximum respiratory rate and mean heart rate measured every minute using a monitor can warn family caregivers and care staff, with the support of palliative care professionals, of imminent death among dying patients at home or other facilities.

Effects of Hand Holding on Anxiety and Pain During Prostate Biopsies: A Pilot Randomized Controlled Trial.

BackgroundEffective pain management is limited for patients during prostate biopsy (PBx). Touch support, such as hand holding, has stress-buffering benefits and effective analgesic effects. We conducted a prospective, single-center randomized clinical trial to assess whether hand holding can reduce patient anxiety, pain, and dissatisfaction during PBx.MethodsBetween April 2020 and October 2020, 120 male patients were randomized into three groups: a hand holding with relatives (HR) group, a hand holding with strangers (HS) group and a control group. A visual analog scale (VAS) was used for self-assessments of pain and satisfaction. Anxiety levels were quantified according to the State-Trait Anxiety Inventory (STAI). Hemodynamic changes were also measured.ResultsThe degree of pain and anxiety in the hand-holding groups was significantly better than that in the control group (P<0.001), and the patients were more willing to undergo repeat PBx (P=0.017). The anxiety levels in the HR group were significantly lower than those in the HS group (P=0.019). During PBx, the changes in systolic blood pressure and heart rate in the hand-holding groups were more stable than those in the control group (P<0.01), and the fluctuations in heart rate in the HR group were smaller than those in the HS group (P<0.01).ConclusionHand holding, especially with relatives, can promote incremental reductions in anxiety, pain and dissatisfaction in patients during PBx. Hence, we recommend hand holding with relatives as an effective adjunct during PBx.

Effect of Earmuffs on Physiological Parameters of Preterm Neonates Nursed in Incubators: A Before-and-After Study

To determine the effect of earmuffs on stability of physiological parameters i.e. heart rate, respiratory rate, and oximeter saturation (SpO2) in preterm neonates. Non-randomized, cross-over study. 60 stable preterm neonates observed without and with earmuffs for 2 hours each (control and intervention periods, respectively). The above parameters were recorded every 60 seconds. Spikes of parameters and fluctuation [by coefficient of variation (CoV)] were compared between periods. Spikes of all parameters, as a proportion of observations, were significantly less in intervention period. Median (IQR) spikes per subject were lower in intervention vs control: tachycardia [2.5 (2.5, 18) vs. 20.5 (2.2, 37.7); P<0.01]; tachypnea [11.5 (11.5, 25) vs. 18 (2, 40) vs; P=0.01] and hypoxia [0 (0, 0) vs. 0 (0, 1.75); P<0.01]. There was significantly less fluctuation of heart rate and SpO2 with earmuffs. Earmuffs improve physiological stability of preterms.

Bispectral-Based Ultrasound Image Restoration Algorithm for Neurological Disorders Analysis in Patients Anesthetized with Sevoflurane

The aim of this work was to investigate preventive effect of dexmedetomidine combined with sevoflurane on neurological disorders in liver cancer patients during postoperative recovery under the ultrasound image restoration (UIR) algorithm. A blind deconvolution medical UIR algorithm was established in this study. The patients anesthetized with sevoflurane for liver cancer surgery were rolled into an experimental group (group A) (dexmedetomidine treatment before surgery) and a control group (group B) (normal saline treatment before surgery). They were monitored routinely before, during, and after surgery, and immune and liver functions of patients were observed before and after surgery. Besides, their cognitive function and adverse reactions were assessed after surgery. Results showed that patients from group A had smaller fluctuation in average arterial blood pressure and heart rate, but their bispectral index (BIS) increased obviously after surgery in contrast to those of group B ( P &lt; 0.05 ). Moreover, changes of immune and liver functions in patients from group A decreased sharply compared with group B ( P &lt; 0.05 ). The postoperative minimental state examination (MoCA) score of patients from group A was 27.51 ± 2.02, while the score of group B was 25.79 ± 2.35. The postoperative (MoCA) score of group A was markedly higher than the score of group B, and the difference was statistically obvious ( P &lt; 0.05 ). Besides, the incidence of postoperative cognitive dysfunction (POCD) in patients from group A and B was 12.91% and 32.26% in turn. The incidence of POCD in patients from group A was sharply lower than the incidence of group B ( P &lt; 0.05 ). In addition, the total incidence of adverse reactions in patients from group A was 6.45%, which was significantly lower than the 22.58% of group B, and the difference was statistically substantial ( P &lt; 0.05 ). In summary, dexmedetomidine combined with sevoflurane could effectively reduce POCD and promote systemic circulation recovery, which had clinical application value.

Altered Relationship Between Heart Rate Variability and fMRI-Based Functional Connectivity in People With Epilepsy.

Background: Disruptions in central autonomic processes in people with epilepsy have been studied through evaluation of heart rate variability (HRV). Decreased HRV appears in epilepsy compared to healthy controls, suggesting a shift in autonomic balance toward sympathetic dominance; recent studies have associated HRV changes with seizure severity and outcome of interventions. However, the processes underlying these autonomic changes remain unclear. We examined the nature of these changes by assessing alterations in whole-brain functional connectivity, and relating those alterations to HRV.Methods: We examined regional brain activity and functional organization in 28 drug-resistant epilepsy patients and 16 healthy controls using resting-state functional magnetic resonance imaging (fMRI). We employed an HRV state-dependent functional connectivity (FC) framework with low and high HRV states derived from the following four cardiac-related variables: 1. RR interval, 2. root mean square of successive differences (RMSSD), 4. low-frequency HRV (0.04–0.15 Hz; LF-HRV) and high-frequency HRV (0.15–0.40 Hz; HF-HRV). The effect of group (epilepsy vs. controls), HRV state (low vs. high) and the interactions of group and state were assessed using a mixed analysis of variance (ANOVA). We assessed FC within and between 7 large-scale functional networks consisting of cortical regions and 4 subcortical networks, the amygdala, hippocampus, basal ganglia and thalamus networks.Results: Consistent with previous studies, decreased RR interval (increased heart rate) and decreased HF-HRV appeared in people with epilepsy compared to healthy controls. For both groups, fluctuations in heart rate were positively correlated with BOLD activity in bilateral thalamus and regions of the cerebellum, and negatively correlated with BOLD activity in the insula, putamen, superior temporal gyrus and inferior frontal gyrus. Connectivity strength in patients between right thalamus and ventral attention network (mainly insula) increased in the high LF-HRV state compared to low LF-HRV; the opposite trend appeared in healthy controls. A similar pattern emerged for connectivity between the thalamus and basal ganglia.Conclusion: The findings suggest that resting connectivity patterns between the thalamus and other structures underlying HRV expression are modified in people with drug-resistant epilepsy compared to healthy controls.