Time-domain Heart Rate Variability Parameters Research Articles

Abstract P299: Alteration of Cardiac Autonomic Function Through Inhalation of Biogenic Volatile Organic Compounds

Background: There is an inverse relationship between exposure to greenspaces and prevalence of cardiovascular disease and cardiovascular disease risk factors. More specifically, green exposure is associated with electrocardiogram (ECG) changes, suggesting a potential alteration of cardiac autonomic balance. One proposed mechanism by which cardiac autonomic balance may be altered is a direct physiologic effect of inhalable plant derived compounds, or biogenic volatile organic compounds (bVOCs), including limonene, α- and β-pinene which are commonly released from vegetation. Therefore, we examined the relationship between acute exposure of isolated bVOCs and cardiac autonomic tone. Hypothesis: We hypothesize that controlled exposure to isolated individual bVOCs will decrease cardiac sympathetic tone. Methods: Under controlled conditions after a bVOC washout period, healthy adults ages 18-70 were exposed to limonene (n=32), α-pinene (n=24), β-pinene (n=17), and a control (room air, n=9). Exposure consisted of one inhalation every 30 seconds for a total of 5 minutes (10 inhalations total). Pre- and post-exposure measurements of supine heart rate variability (HRV) were conducted following a 10-minute rest period. HRV was analyzed using a clean, 5-minute epoch with >95% effective data length. Statistical analysis was performed using paired t-tests to determine changes in HR and HRV. Significance level was set at p<0.05, a priori . Results: Our population was primarily female (56%, 18 of 32), white (53%, 17 of 32), high income (47%, 15 of 32), and had an education higher than a 4-year degree (62.5%, 20 of 32). There were significant decreases in HR when exposed to limonene (pre: 64.87±9.86bpm vs. post: 63.26±9.10bpm, p<.001) and α-pinene (pre: 63.98±9.32bpm vs. post: 61.64±9.72bpm, p=.008), along with trends seen in β-pinene (pre: 65.78±10.60bpm vs. post: 63.74±9.65bpm, p=.066). Control exposure showed no difference (pre: 65.40±8.38bpm vs. post: 64.14±9.35bpm, p=.301). Normalized low- (LF) and high-frequency (HF) HRV parameters showed no change across isolated bVOCs, however the LF/HF ratio scores decreased significantly following β-pinene exposure (pre: 1.62±1.69 vs. post: 0.96±0.96, p=.039). HRV time-domain parameters RMSSD and SDNN did not change following isolate exposure. Conclusions: Post-exposure decreases in HR and LFHF ratios indicate the potential for cardiovascular disease risk reduction from bVOC exposure leading to decreased sympathetic tone. Additional work is required to determine the mechanism of exposure-related changes.

Effect of Prenatal Yoga versus Moderate-Intensity Walking on Cardiorespiratory Adaptation to Acute Psychological Stress: Insights from Non-Invasive Beat-to-Beat Monitoring.

We recently reported enhanced parasympathetic activation at rest throughout pregnancy associated with regular yoga practice. The present study presents a secondary analysis of data collected within a prospective cohort study of 33 pregnant women practicing yoga once weekly throughout pregnancy and 36 controls not involved in formal pregnancy exercise programs. The objective was to assess the impact of prenatal yoga on the autonomic nervous system stress response. Healthy pregnant women with singleton pregnancies were recruited in the first trimester. There was no significant difference in the maternal body mass index (BMI) between the yoga group and the controls (24.06 ± 3.55 vs. 23.74 ± 3.43 kg/m2, p = 0.693). Women practicing yoga were older (28.6 ± 3.9 vs. 31.3 ± 3.5 years, p = 0.005) and more often nulliparous (26 (79%) vs. 18 (50%), p = 0.001). We studied heart rate variability (HRV) parameters in the time domain (SDNN, standard deviation of regular R-R intervals, and RMSSD, square root of mean squared differences of successive R-R intervals) and frequency domain (ln(LF/HF), natural logarithm of low-frequency to high-frequency power), as well as synchronization indices of heart rate, blood pressure and respiration during and immediately following acute psychological stress of a standardized mental challenge test. Measurements were performed once per trimester before and after yoga or a 30 min moderate-intensity walk. Statistical comparison was performed using three-way analyses of variance (p < 0.05 significant). Time domain HRV parameters during and following mental challenge in the yoga group were significantly higher compared to the controls regardless of the trimester (F = 7.22, p = 0.009 for SDNN and F = 9.57, p = 0.003 for RMSSD, respectively). We observed no significant differences in the yoga group vs. the controls in terms of ln(LF/HF) and synchronization indices. Regular prenatal yoga practice was associated with a significantly reduced sympathetic response to mental challenge and quicker recovery after acute psychological stress. These effects persisted throughout pregnancy with regular practice.

Time-domain heart rate dynamics in the prognosis of progressive atherosclerosis

Background and aimThe regular uptake of a high-fat diet (HFD) with changing lifestyle causes atherosclerosis leading to cardiovascular diseases and autonomic dysfunction. Therefore, the current study aimed to investigate the correlation of autonomic activity to lipid and atherosclerosis markers. Further, the study proposes a support vector machine (SVM) based model in the prediction of atherosclerosis severity. Methods and resultsThe Lead-II electrocardiogram and blood markers were measured from both the control and the experiment subjects each week for nine consecutive weeks. The time-domain heart rate variability (HRV) parameters were derived, and the significance level was tested using a one-way Analysis of Variance. The correlation analysis was performed to determine the relation between autonomic parameters and lipid and atherosclerosis markers. The statistically significant time-domain values were used as features of the SVM. The observed results demonstrated the reduced time domain HRV parameters with the increase in lipid and atherosclerosis index markers with the progressive atherosclerosis severity. The correlation analysis revealed a negative association between time-domain HRV parameters with lipid and atherosclerosis parameters. The percentage accuracy increases from 86.58% to 98.71% with the increase in atherosclerosis severity with regular consumption of HFD. ConclusionsAtherosclerosis causes autonomic dysfunction with reduced HRV. The negative correlation between autonomic parameters and lipid profile and atherosclerosis indexes marker revealed the potential role of vagal activity in the prognosis of atherosclerosis progression. The support vector machine presented a respectable accuracy in the prediction of atherosclerosis severity from the control group.

The Heart's Function as a Pump Assessed via Impedance Cardiography and the Autonomic System Balance in Patients with Early-Stage Acromegaly.

Acromegaly is a rare, chronic disease that involves structural and functional abnormalities of the cardiovascular system. Acromegaly likely affects interactions between the cardiovascular system and the autonomic nervous system (ANS). Therefore, assessing the relationship between sympathetic-parasympathetic balance by analyzing heart rate variability (HRV) and the hemodynamic profile via impedance cardiography (ICG) may be useful in learning the exact nature of interactions between the ANS and the cardiovascular system. The purpose of this study was to assess a possible association between HRV and ICG-based parameters of cardiac function in patients newly diagnosed with acromegaly. This observational cohort study was conducted on 33 patients (18 men, mean age of 47 years) newly diagnosed with acromegaly and no significant comorbidities. A correlation analysis (Spearman's rank coefficient R) of the parameters assessed via ICG and the HRV assessed via 24 h ambulatory electrocardiography was performed. ICG assessments included the following parameters: stroke volume index (SI), cardiac index (CI), acceleration index (ACI), velocity index (VI), and Heather index (HI). The analysis of HRV included both time-domain parameters (pNN50, SDNN, SDSD, rMSSD) and frequency-domain parameters (total power (TP) and its individual frequency bands: low-frequency (LF day/night), high-frequency (HF day/night), and the LF/HF ratio (day/night)). Frequency-domain HRV analysis showed the following correlations: (1) lower nighttime LF values with higher ACI (R = -0.38; p = 0.027) and HI (R = -0.46; p = 0.007) values; (2) higher nighttime HF values with higher ACI (R = 0.39; p = 0.027) and HI (R = 0.43; p = 0.014) values; (3) lower nighttime LF/HF values with higher ACI (R = -0.36; p = 0.037) and HI (R = -0.42; p = 0.014) values; (4) higher nighttime TP values with higher SI values (R = 0.35; p = 0.049). Time-domain parameters of HRV showed a significant correlation only between the nighttime values of SDSD and SI (R = 0.35; p = 0.049) and between the daytime and nighttime values of SDNN and HR (R = -0.50; p = 0.003 and R = -0.35; p = 0.046). In multivariate regression, only ACI was revealed to be independently related to HRV. In patients newly diagnosed with acromegaly, the relationship between the sympathetic-parasympathetic balance assessed via HRV and the hemodynamic profile assessed via ICG was revealed. Better function of the left ventricle was associated with a parasympathetic shift in the autonomic balance.

Comparison of time domain indices of heart rate variability between alcohol-dependent individuals and non-alcoholic subjects

Background: Alcohol dependence develops because of repeated alcohol intake. Alcohol damages the cardiac autonomic nerve fibers leading to autonomic imbalance, resulting in reduced heart rate variability (HRV). HRV refers to the complex beat-to-beat variation in the heart rate, produced by the interplay of sympathetic and parasympathetic neural activity at the Sino-atrial node. Our body works effectively in parasympathetic activity dominance. The time domain indices of HRV are specific markers of parasympathetic activity. A decrease in the time domain parameters indicates reduced parasympathetic activity in the heart, indicating cardiac autonomic dysfunction with vagal neuropathy. Aims and Objectives: The objectives of the study are as follows: (1) To assess the HRV in alcohol-dependent individuals using time domain indices. (2) To compare the HRV between alcoholic-dependent individuals and non-alcoholic subjects. Materials and Methods: A total of 110 individuals in the age group of 20–55 years were recruited for our study. Among them, 55 were alcohol-dependent individuals selected based on the diagnostic and statistical manual-IV, international classification of diseases-10 criteria, and 55 age and gender-matched volunteers were selected as healthy non-alcoholic controls. Short-term HRV was recorded in a supine posture, and the results were interpreted. Statistical analysis was done using the software SPSS version 21.0. Results: Our results showed a significant reduction in the time-domain parameters of HRV – SDNN, RMSSD, NN50, and pNN50 in the alcohol-dependent individuals compared to the controls, suggesting reduced parasympathetic activity in the heart indicating cardiac autonomic neuropathy. Conclusion: Alcohol affects the cardiac autonomic status leading to sudden death due to arrhythmias. HRV can be used as a non-invasive test to assess cardiac autonomic dysfunction and its biofeedback can help alcohol-dependent individuals to adopt healthy lifestyle measures.

Unveiling the acute neurophysiological responses to strength training: An exploratory study on novices performing weightlifting bouts with different motor learning models.

Currently, there is limited evidence regarding various neurophysiological responses to strength exercise and the influence of the adopted practice schedule. This study aimed to assess the acute systemic effects of snatch training bouts, employing different motor learning models, on skill efficiency, electric brain activity (EEG), heart rate variability (HRV), and perceived exertion as well as mental demand in novices. In a within-subject design, sixteen highly active males (mean age: 23.13 ± 2.09 years) randomly performed snatch learning bouts consisting of 36 trials using repetitive learning (RL), contextual interference (blocked, CIb; and serial, CIs), and differential learning (DL) models. Spontaneous resting EEG and HRV activities were recorded at PRE and POST training bouts while measuring heart rate. Perceived exertion and mental demand were assessed immediately after, and barbell kinematics were recorded during three power snatch trials performed following the POST measurement. The results showed increases in alpha, beta, and gamma frequencies from pre- to post-training bouts in the majority of the tested brain regions (p values ranging from < 0.0001 to 0.02). The CIb model exhibited increased frequencies in more regions. Resting time domain HRV parameters were altered following the snatch bouts, with increased HR (p < 0.001) and decreased RR interval (p < 0.001), SDNN, and RMSSD (p values ranging from < 0.0001 to 0.02). DL showed more pronounced pulse-related changes (p = 0.01). Significant changes in HRV frequency domain parameters were observed, with a significant increase in LFn (p = 0.03) and a decrease in HFn (p = 0.001) registered only in the DL model. Elevated HR zones (> HR zone 3) were more dominant in the DL model during the snatch bouts (effect size = 0.5). Similarly, the DL model tended to exhibit higher perceived physical (effect size = 0.5) and mental exertions (effect size = 0.6). Despite the highest psycho-physiological response, the DL group showed one of the fewest significant EEG changes. There was no significant advantage of one learning model over the other in terms of technical efficiency. These findings offer preliminary support for the acute neurophysiological benefits of coordination-strength-based exercise in novices, particularly when employing a DL model. The advantages of combining EEG and HRV measurements for comprehensive monitoring and understanding of potential adaptations are also highlighted. However, further studies encompassing a broader range of coordination-strength-based exercises are warranted to corroborate these observations.

The 24-Hour Cardiac Autonomic Activity in Patients With Allergic Rhinitis.

Definitive knowledge of the 24-hour cardiac autonomic activity in patients with allergic rhinitis (AR) is lacking. Thus, we aimed to evaluate heart rate variability (HRV), which is used to measure cardiac autonomic activity by 24-hour Holter monitoring in patients with AR. We enrolled 32 patients who visited our clinic and were diagnosed with AR. The control group was selected four-fold (n = 128) by matching (age, sex, hypertension, and diabetes) in the AR group from a Holter registry in the cardiology department. The HRV results, which were measured using 24-hour Holter monitoring, were compared between the AR and control groups. All time-domain parameters of HRV revealed no differences between the groups. However, among the frequency domain parameters of HRV, the low-frequency to high-frequency ratio and low-frequency power in normalized units were significantly lower in the AR group. Conversely, high-frequency power in normalized units was significantly higher in the AR group. In the multiple regression analysis, AR was independently associated with sympathetic withdrawal (adjusted odds ratio = 3.393, P = 0.020) after adjusting for age, sex, hypertension, diabetes mellitus, and hyperlipidemia. The present findings suggest differences in cardiac autonomic activity which are related with sympathetic withdrawal in patients with AR compared with that in the normal population over 24 hours.

Anthracycline's Effects on Heart Rate Variability in Children with Acute Lymphoblastic Leukemia: Early Toxicity Signs-Pilot Study.

Anthracycline treatments are known to cause cardiotoxic long-term side effects in cancer survivors. Recently, a decrease in heart rate variability (HRV) has been identified in these patients, signaling autonomic dysfunction and altered cardiac fitness. This study aimed at evaluating changes in HRV in children treated with anthracyclines. A total of 35 pediatric patients with acute lymphoblastic leukemia were evaluated by means of a 24 h Holter ECG, at baseline and after reaching half the total cumulative dose of doxorubicin equivalent (120 mg/m2). Parameters of HRV were assessed, as well as any arrhythmic episodes, bradycardia and tachycardia percentages. The results showed a significant decrease in both time-domain and frequency-domain HRV parameters, following anthracycline treatment. The low-frequency (LF) to high-frequency (HF) parameters' ratio also displayed a significant difference (p = 0.035), suggestive of early cardiac autonomic dysfunction. Of note, none of the patients presented symptoms of heart disease or elevated troponins, and only two patients presented echocardiographic signs of diastolic dysfunction. The present study showed that cardiac autonomic nervous system regulation is compromised in children treated with anthracyclines even before reaching the total cumulative dose. Therefore, HRV parameters could be the first indicators of subclinical cardiac toxicity, making Holter ECG monitoring of the oncological patient a necessity.

Wrist-Worn Sensor Validation for Heart Rate Variability and Electrodermal Activity Detection in a Stressful Driving Environment.

Wearable sensors are widely used to gather psychophysiological data in the laboratory and real-world applications. However, the accuracy of these devices should be carefully assessed. The study focused on testing the accuracy of the Empatica 4 (E4) wristband for the detection of heart rate variability (HRV) and electrodermal activity (EDA) metrics in stress-inducing conditions and growing-risk driving scenarios. Fourteen healthy subjects were recruited for the experimental campaign, where HRV and EDA were recorded over six experimental conditions (Baseline, Video Clip, Scream, No-Risk Driving, Low-Risk Driving, and High-Risk Driving) and by means of two measurement systems: the E4 device and a gold standard system. The overall quality of the E4 data was investigated; agreement and reliability were assessed by performing a Bland-Altman analysis and by computing the Spearman's correlation coefficient. HRV time-domain parameters reported high reliability levels in Baseline (r > 0.72), Video Clip (r > 0.71), and No-Risk Driving (r > 0.67), while HRV frequency domain parameters were sufficient in Baseline (r > 0.58), Video Clip (r > 0.59), No-Risk (r > 0.51), and Low-Risk Driving (r > 0.52). As for the EDA parameters, no correlation was found. Further studies could enhance the HRV and EDA quality through further optimizations of the acquisition protocol and improvement of the processing algorithms.

Best Parameters of Heart Rate Variability for Assessing Autonomic Responses to Brief Rectal Distention in Patients with Irritable Bowel Syndrome.

Heart rate variability (HRV) has been used to measure autonomic nervous system (ANS) activity noninvasively. The purpose of this study was to identify the most suitable HRV parameters for ANS activity in response to brief rectal distension (RD) in patients with Irritable Bowel Syndrome (IBS). IBS patients participated in a five-session study. During each visit, an ECG was recorded for 15 min for baseline values and during rectal distension. For rectal distension, a balloon was inflated in the rectum and the pressure was increased in steps of 5 mmHg for 30 s; each distension was followed by a 30 s rest period when the balloon was fully deflated (0 mmHg) until either the maximum tolerance of each patient was reached or up to 60 mmHg. The time-domain, frequency-domain and nonlinear HRV parameters were calculated to assess the ANS activity. The values of each HRV parameter were compared between baseline and RD for each of the five visits as well as for all five visits combined. The sensitivity and robustness/reproducibility of each HRV parameter were also assessed. The parameters included the Sympathetic Index (SI); Root Mean Square of Successive Differences (RMSSD); High-Frequency Power (HF); Low-Frequency Power (LF); Normalized HF Power (HFn); Normalized LF Power (LFn); LF/HF; Respiratory Sinus Arrhythmia (RSA); the Poincare Plot's SD1, SD2 and their ratio; and the pNN50, SDSD, SDNN and SDNN Index. Data from 17 patients were analyzed and compared between baseline and FD and among five sessions. The SI was found to be the most sensitive and robust HRV parameter in detecting the ANS response to RD. Out of nine parasympathetic parameters, only the SDNN and SDNN Index were sensitive enough to detect the parasympathetic modulation to RD during the first visit. The frequency-domain parameters did not show any change in response to RD. It was also observed that the repetitive RD in IBS patients resulted in a decreased autonomic response due to habituation because the amount of change in the HRV parameters was the highest during the first visit but diminished during subsequent visits. In conclusion, the SI and SDNN/SDNN Index are most sensitive at assessing the autonomic response to rectal distention. The autonomic response to rectal distention diminishes in repetitive sessions, demonstrating the necessity of randomization for repetitive tests.

A Serious Game to Self-Regulate Heart Rate Variability as a Technique to Manage Arousal Level Through Cardiorespiratory Biofeedback: Development and Pilot Evaluation Study.

Heart rate variability biofeedback (HRVB) is an established intervention for increasing heart rate variability (HRV) in the clinical context. Using this technique, participants become aware of their HRV through real-time feedback and can self-regulate it. The aim of this study was 2-fold: first, to develop a serious game that applies the HRVB technique to teach participants to self-regulate HRV and, second, to test the app with participants in a pilot study. An HRVB app called the FitLab Game was developed for this study. To play the game, users must move the main character up and down the screen, avoiding collisions with obstacles. The wavelength that users must follow to avoid these obstacles is based on the user's basal heart rate and changes in instantaneous heart rate. To test the FitLab Game, a total of 16 participants (mean age 23, SD 0.69 years) were divided into a control group (n=8) and an experimental group (n=8). A 2 × 2 factorial design was used in each session. Participants in the experimental condition were trained in breathing techniques. Changes in the frequency and time domain parameters of HRV and the game's performance features were evaluated. Significant changes in the average RR intervals and root mean square of differences between adjacent RR intervals (RMSSD) were found between the groups (P=.02 and P=.04, respectively). Regarding performance, both groups showed a tendency to increase the evaluated outcomes from baseline to the test condition. The results may indicate that playing different levels leads to an improvement in the game's final score by repeated training. The tendency of changes in HRV may reflect a higher activation of the mental system of attention and control in the experimental group versus the control group. In this context, learning simple, voluntary strategies through a serious game can aid the improvement of self-control and arousal management. The FitLab Game appears to be a promising serious game owing to its ease of use, high engagement, and enjoyability provided by the instantaneous feedback.

Effects of high intensity interval-based inspiratory muscle training in patients with heart failure: A single-blind randomized controlled trial

BackgroundGiven the promising effects of inspiratory muscle training (IMT), determining the most appropriate IMT protocol will optimize the training benefits. ObjectivesThe objective of this study was to determine the effects of high intensity interval-based inspiratory muscle training (H-IMT) on cardiovascular, pulmonary, physical, and psychosocial functions in patients with heart failure and reduced ejection fraction (HFrEF). MethodsThirty-four patients with HFrEF were randomly assigned to the H-IMT or control group for 3 days/week, 8 weeks training period. The H-IMT group performed IMT at least 70% of the maximal inspiratory pressure, whereas the control group performed unloaded IMT. Each session occurred 7 sets with a total of 21 min consisting of 2-min training and 1-min interval. Heart rate variability (HRV), arterial stiffness, respiratory muscle strength and endurance, diaphragm thickness, quadriceps strength, functional capacity, frailty, dyspnea, fatigue, disease-specific health-related quality of life (HRQoL), and generic HRQoL were evaluated at baseline and after 8 weeks training period by blinded assessors. ResultsStatistically significant between-group differences were observed in the time domain parameters of HRV, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific HRQoL in favor of the H-IMT group (p<0.05). ConclusionsH-IMT is an effective protocol for improving cardiac autonomic function, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific quality of life in patients with HFrEF. Clinical trial registrationNCT04839211

Effects of Three-Hour Wearing Personal Protective Equipment on Heart Rate Variability in Healthcare Workers for the Treatment of COVID-19 Patients.

Personal protective equipment (PPE), an essential shield to protect healthcare workers (HCWs) during the COVID-19 pandemic, has been reported to affect their heart rate variability (HRV). To investigate the changes of very short-term heart rate variability in HCWs after three hours of wearing PPE to treat COVID-19 patients at different working times and intensities, and related factors. Sixty-five healthy HCWs were enrolled at the Number 2 Infectious Field Hospital (formed by Military Hospital 103), Vietnam. Two-minute 12-lead electrocardiograms were recorded before wearing and after removing PPE. After three hours of wearing PPE, the mean heart rate of HCWs increased (p = 0.048) meanwhile, the oxygen saturation decreased significantly (p = 0.035). Standard deviation of all normal to normal intervals (SDNN), mean intervals RR (mean NN), and root mean square successive difference (rMSSD) after wearing PPE was also reduced significantly. SDNN, Mean NN, and rMSSD decreased as the working intensity increased (as in mild, moderate, and severe patient departments). In univariate regression analysis, logSDNN, logmean NN and logrMSSD were positively correlated with SpO2 and QT interval (r = 0.14, r = 0.31, r = 0.25; r = 0.39, r = 0.77, r = 0.73, respectively) and were negatively correlated with ambient temperature inside PPE (r = -0.41, r = -0.405, r = -0.25, respectively) while logmean NN and log rMSSD were negatively correlated with diastolic blood pressure (r = -0.43, r = -0.39, respectively). In multivariable regression analysis, logSDNN and logmean NN were negatively correlated to ambient temperature inside PPE (r = -0.34, r = -0.18, respectively). Time-domain heart rate variability decreased after wearing PPE. Time-domain HRV parameters were related to ambient temperature inside PPE, diastolic blood pressure, QT interval, and SpO2.

HEART RATE VARIABILITY PARAMETERS WERE NOT ASSOCIATED WITH 30-DAY ALL-CAUSE MORTALITY IN INTENSIVE CARE UNIT PATIENTS WITH OR WITHOUT ATRIAL FIBRILLATION: A RETROSPECTIVE STUDY OF THE MIMIC-IV DATABASE.

Objective: Our study aims to evaluate the association between heart rate variability (HRV) and short- and long-term prognosis in patients admitted to intensive care unit (ICU). Methods and Results: Adult patients continuously monitored for over 24 h in ICUs from the the American Medical Information Mart for Intensive Care (MIMIC)-IV Waveform Database were recruited in our study. Twenty HRV-related variables (8 time domain, 6 frequency domain, and 6 nonlinear variables) were calculated based on RR intervals. The association between HRV and all-cause mortality was assessed. Ninety-three patients met the inclusion criteria and were classified into atrial fibrillation (AF) and sinus rhythm (SR) groups, which were further divided into 30-day survivor group and nonsurvivor\groups based on their survival status. The 30-day all-cause mortality rates in AF and SR groups were 36.3% and 14.6%, respectively. All the time domain, frequency domain, and nonlinear HRV parameters did not differ significantly between survivors and nonsurvivors with or without AF (all P > 0.05). Presence of renal failure, malignancy, and elevated blood urea nitrogen level were associated with increased 30-day all-cause mortality in SR patients, while presence of sepsis, infection, higher platelet count, and magnesium level were associated with increased 30-day all-cause mortality in AF patients. Conclusions: Heart rate variability variables were not associated with increased 30-day all-cause mortality in ICU patients with or without AF.

Heart Rate Variability in Patients with Spontaneous Intracerebral Hemorrhage and its Relationship with Clinical Outcomes.

Although abnormal heart rate variability (HRV) is frequently observed in patients with spontaneous intracerebral hemorrhage (ICH), its time course and presentation of different indices remain unclear, and few studies have focused on its association with clinical outcomes. We prospectively recruited consecutive patients with spontaneous ICH between June 2014 and June 2021. HRV was evaluated twice during hospitalization (within 7days and 10-14days after stroke). Time and frequency domain indices were calculated. A modified Rankin Scale score ≥ 3 at 3months was defined as a poor outcome. Finally, 122 patients with ICH and 122 age- and sex-matched volunteers were included. Compared with controls, time domain and absolute frequency domain HRV parameters (total power, low frequency [LF], and high frequency [HF]) in the ICH group were significantly decreased within 7days and 10-14days. For relative values, normalized LF (LF%) and LF/HF were significantly higher, whereas normalized HF (HF%) was significantly lower, in the patient group than in the control group. Furthermore, LF% and HF% measured at 10-14days were independently associated with 3-month outcomes. HRV values were impaired significantly within 14days after ICH. Furthermore, HRV indices measured 10-14days after ICH were independently associated with 3-month outcomes.

Heart rate and heart rate variability during diagnostic and interventional neuroendovascular procedures.

Heart rate variability (HRV) reflects the activity of the autonomic nervous system (ANS) and can be used as a potential predictor of stress-related cardiovascular diseases. This study aimed to assess whether physical and mental strain during the performance of cerebral endovascular procedure influence time-domain HRV parameters in operating surgeon. Heart rate (HR) and HRV metrics were measured using a HR sensor chest strap before, during, and after neuroendovascular interventions performed by a single neurosurgeon. Three consecutive data series were reported by recording time domain: before procedure, during and after performing endovascular procedures. HR and HRV parameters were recorded during diagnostic and interventional neuroendovascular procedures. HR and HRV measures were analyzed by procedure type and recording time domain. HRV measures of a single endovascular neurosurgeon were recorded during 50 procedures. The median intraprocedural HRV score was the lowest and the median HR was the highest (HRV: 52, HR: 89 bpm) compared to preprocedural (HRV: 59, HR: 70 bpm) and postprocedural cardiovascular measures (HRV: 53, HR: 79, bpm, p < 0.001). On univariate linear regression, a negative association of interventional procedures with lower intraprocedural (β = -0.905, p = 0.001) and postprocedural (β = -1.12, p < 0.001) HRV scores compared to the diagnostic procedures was noted. HRV is a reliable tool to measure cardiovascular and mental stress. Interventional neuro-endovascular procedures seem to negatively impact the cardiovascular measures of neurointerventionalists. Further longitudinal studies utilizing HRV are warranted to address their long-term effects on the mental health of physicians.

Diabetic cardiac autonomic neuropathy: Omega-3 polyunsaturated fatty acids and heart rate variability

The aim of the study was to analyze the effect of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) on the heart rate variability (HRV) parameters in patients with type 2 diabetes mellitus (T2DM) and advanced stage of cardiovascular autonomic neuropathy (CAN). We have examined 36 patients with T2DM and definite stage of CAN, aged between 50-59 years with disease duration 1-6 years and median glycated hemoglobin A1c 7.1%±0.12%. Patients were divided into 2 groups. The first group received traditional antihyperglycemic therapy (n=15, control) for three months; patients in group 2 (n=21) received in addition 1 g/day of the ω-3 PUFAs for three months. Results. Prescription of the ω-3 PUFAs to the patients with T2DM and definite stage of СAN was accompanied by a statistically significant increase of the time-domain HRV parameters; the spectral HRV parameters during the active and passive periods compared to the control group. Conclusion. Obtained results suggest that the efficacy of ω-3 PUFAs is the result of a direct effect of the ω-3 PUFAs on the investigated indexes.

Heart Rate Variability Impairment Is Associated with Right Ventricular Overload and Early Mortality Risk in Patients with Acute Pulmonary Embolism.

The association between heart rate variability (HRV) and mortality risk of acute pulmonary embolism (APE), as well as its association with right ventricular (RV) overload is not well established. We performed an observational study on consecutive patients with confirmed APE. In the first 48 h after admission, 24 h Holter monitoring with assessment of time-domain HRV, echocardiography and NT-proBNP (N-terminal pro-B-type natriuretic peptide) measurement were performed in all participants. We pre-examined 166 patients: 32 (20%) with low risk of early mortality, 65 (40%) with intermediate-low, 65 (40%) with intermediate-high, and 4 (0.02%) in the high risk category. The last group was excluded from further analysis due to sample size, and finally, 162 patients aged 56.3 ± 18.5 years were examined. We observed significant correlations between HRV parameters and echocardiographic signs of RV overload. SDNN (standard deviation of intervals of all normal beats) correlated with echocardiography-derived RVSP (right ventricular systolic pressure; r = -0.31, p = 0.001), TAPSE (tricuspid annulus plane systolic excursion; r = 0.21, p = 0.033), IVC (inferior vena cava diameter; r = -0.27, p = 0.002) and also with NT-proBNP concentration (r = -0.30, p = 0.004). HRV indices were also associated with APE risk stratification, especially in the low-risk category (r = 0.30, p = 0.004 for SDNN). Univariate and multivariate analyses confirmed that SDNN values were associated with signs of RV overload. In conclusion, we observed a significant association between time-domain HRV parameters and echocardiographic and biochemical signs of RV overload. Impaired HRV parameters were also associated with worse a clinical risk status of APE.

HEART RATE VARIABILITY IS AFFECTED IN YOUNG ADULT CELIAC PATIENTS, INDICATING AUTONOMIC DYSFUNCTION AND INCREASED CARDIOVASCULAR RISK

Aim: Celiac Disease (CD) is a common autoimmune disease that can present at any age with varied symptoms. Cardiac involvement including vascular and arrhythmic disturbances has an important prognostic value in patients with autoimmune disorders. The aim of this study was to evaluate the effects of CD on cardiovascular autonomic functions by measuring the indices of heart rate variability (HRV).&#x0D; Materials and Methods: Ninety-one CD patients and the ninety-three healthy volunteers were included in the study. We examined both time domain and frequency domain indices of HRV measured by 24-hour ambulatory electrocardiography.&#x0D; Results: All of the time domain and frequency domain HRV parameters, with the exceptions of low frequency power and low frequency to high frequency ratio, were significantly lower in patients with CD compared to the control (p &lt; 0.01). This difference retained for most of the HRV parameters when daytime and nighttime HRV parameters were compared separately. Correlation analysis revealed significant associations of HRV parameters with hemoglobin and ferritin levels and with duration of CD (p &lt; 0.01). No correlation was found between HRV parameters and anti-tissue transglutaminase IgA and IgG levels which indicate the activity of the disease.&#x0D; Conclusion: The study confirmed that patients with CD have reduced HRV, indicating the presence of objective autonomic dysfunction and increased cardiovascular risk.

Effect of slow breathing exercise on heart rate variability in tension-type headache female patients: A time domain analysis

Background: Tension-type headache (TTH), the most frequently occurring primary headache is associated with autonomic dysfunction. Time domain analysis of heart rate variability (HRV) is a popular tool to detect changes in cardiac autonomic nerve function (CANF) in TTH patients. Slow breathing exercise (SBE) can significantly improve HRV in patients with cardiovascular disorders. Objective: To observe the effect of SBE on HRV by time domain analysis in TTH female patients. Methods: This quasi-experimental study was conducted from March 2021 to February 2022 in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka on 60 female TTH patients aged 20-45 years. Thirty patients performed SBE every morning and evening for 30 minutes in addition to receiving conventional treatment and 30 patients continued only conventional treatment without any exercise for 90 days. Thirty age, sex and BMI matched apparently healthy control were enrolled who did not perform SBE or any other exercise. All subjects were assessed at baseline and also after 90 days. Time domain HRV parameters were recorded by Power Lab 8/35 AD Instruments, Australia. One way ANOVA followed by post-hoc test and Paired sample t-test were performed for statistical analysis and p&lt;0.05 was considered as statistical significance. Results: Mean heart rate (HR) was significantly higher (p&lt;0.001) and SDRR (Standard deviation of all RR interval); CVRR (Coefficient variation of RR interval); SDSD (Standard deviation of successive RR interval differences between adjacent RR intervals); RMSSD (Square root of mean of squared differences of successive RR interval) and pRR50% (Proportion of RR interval with duration &gt; 50ms) were significantly lower (p&lt;0.001) in TTH female patients compared to control at baseline. Significant decrement of mean HR (p&lt;0.001) and increment of all other time domain parameters (p&lt;0.001) was observed after 90 days of SBE. Again, significantly decreased SDRR, CVRR, SDSD, RMSSD and pRR50% (p&lt;0.001, p&lt;0.01) was observed in the patients who did not perform SBE. Conclusion: SBE may effectively improve cardiac autonomic dysfunction in TTH female patients. J Bangladesh Soc Physiol. 2022, June; 17(1): 56-63