Short-term Heart Rate Variability Research Articles

Chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality. About 80% of SHS-related deaths are due to cardiovascular causes. Reducing SHS exposure with smoking bans is associated with improved cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a great candidate for combating SHS exposure-induced cardiovascular outcomes. The goals of this study were to determine 1) the time course of environmentally relevant SHS exposure effects on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of a soluble epoxide hydrolase inhibitor (TPPU) can protect against SHS-induced autonomic and cardiovascular dysregulation. Methods: Male C57BL/6J mice (11 wk) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to 12 wks of either filtered air (FA, n=19) or 3 mg/m3 of SHS (6 hr/d, 5 d/wk, n=18), followed by 4 weeks recovery window (SHS substituted with FA). Separate mice were randomly assigned to one of the 3 groups: FA (n=12), FA+TPPU (n=12), and SHS+TPPU (n=22). TPPU (15 mg/l) was given by drinking water during the 12 weeks of exposure period (estimated dose = 3.75 ug/g/day). BP and ECG were recorded continuously for 36 hours every month when mice were not exposed. Data were stratified by 12-hour circadian window: The dark cycle (dark 1) immediately after the 5th day of exposure and the following light and dark (dark 2) cycles. Baroreflex sensitivity (BRS) was determined with the sequence method. Standard time domain heart rate variability (HRV) parameters were obtained from normal-to-normal R-R intervals. Results: SHS-exposed mice had significantly higher physical activity levels (~ 50% higher, p<0.05), an effect that persisted 4 wks after cessation of SHS exposure. SHS exposure significantly decreased 1) short-term HRV (RMSSD) by ~20% as early as after 4 wks of exposure; 2) overall HRV (SDNN) with maximum effect at 12 wks (-15%, p<0.05); 3) pulse pressure (-8%, p<0.05) as early as week 4; and 4) BRS with maximum effect at 12 wks (-11%, p<0.05). All SHS-induced changes in cardiovascular regulation were ameliorated by 4 weeks of recovery. Treatment with TPPU in drinking water eliminated SHS exposure-induced decreases in HRV, PP and BRS. However, SHS-induced increase in activity persisted (30% higher, p<0.05) even with TPPU treatment. Conclusions: These data suggest that 1) Three months of environmentally relevant SHS significantly reduces cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be rescued by removing from SHS exposure; and 3) oral TPPU can prevent SHS-induced cardiovascular dysregulation. R01 ES025229, T32 HL086350, T32 ES007059, R35ES030443 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

PO-05-133 PROLONGED NEUROMODULATION EFFECTS AFTER PULMONARY VEIN ISOLATION IN PATIENTS WITH PAROXYSMAL ATRIAL FIBRILLATION: INSIGHT FROM THE NONLINEAR HEART RATE DYNAMICS

Heart rate variability (HRV) reveals information undetected by direct electrocardiogram morphology evaluation. Prior research indicated that patients with paroxysmal atrial fibrillation (PAF) had altered a short-term linear HRV after pulmonary vein isolation (PVI). However, the long-term changes in the nonlinear heart rate dynamics before and after PVI remain unclear. The objective was to investigate the long-term nonlinear HRV changes before and after PVI in PAF patients. We enrolled 42 drug-refractory symptomatic PAF patients who underwent PVI. Holter monitoring were done less than 1 year before, 1∼3, and 6∼12 months after PVI, respectively. The nonlinear HRV variables, including sample entropy (SampEn), multi-scale entropy (MSE), detrended fluctuation analysis (DFA), and Poincaré Plot analysis, were analyzed. Significant reductions in SD1, SD1/SD2, MSE 1∼5, MSE 6∼20, and SampEn occurred 6∼12 months after when compared to those before PVI, respectively. SD2, MSE slope 5, DFA slope 1 decreased 1∼3 months after PVI when compared to those before PVI, respectively, whereas increased significantly 6∼12 months after PVI when compared to those 1∼3 months after PVI, respectively. DFA slope2 increased significantly after PVI when compared to that before PVI. Detailed parameters are shown in the Table 1. As measured by DFA slope2, fractal correlation properties increased significantly following PVI. Heart rate complexity (MSE 1∼5, MSE 6∼20, and SampEn) and unpredictability of an RR time series (SD1/SD2) decreased significantly after PVI, whereas long-term RR interval (SD2) and short-term complexity (MSE slope 5) decreased in the 1∼3 months after PVI and then increased in 6∼12 months after PVI. These results indicated that the neuromodulation effects from PVI was far more prolonged and extensively than expected.Tabled 1Table 1. Serial changes in the HRV parametersPatients with PAF who underwent PVI (n = 42)< 1 year pre-PVI1∼3 months post-PVI6∼12 months post-PVISD121.16 ± 8.416.31 ± 11.08∗14.19 ± 8.63∗SD2177.58 ± 44.38134.92 ± 37∗146.46 ± 37.52∗+SD1/SD20.12 ± 0.060.12 ± 0.090.1 ± 0.06∗+DFA slope11.11 ± 0.240.8 ± 0.31∗0.94 ± 0.31∗+DFA slope21.07 ± 0.11.16 ± 0.13∗1.15 ± 0.11∗MSE 1∼55.62 ± 1.824.76 ± 1.74∗4.72 ± 1.59∗MSE 6∼2019.81 ± 5.6716.01 ± 5.6∗17.3 ± 4.75∗MSE slope50.06 ± 0.07-0.01 ± 0.09∗0.03 ± 0.07+SampEn1 ± 0.321.01 ± 0.290.9 ± 0.26∗+Data are expressed as (mean ± SD); DFA slope1: Detrended fluctuation analysis slope 1; DFA slope2: Detrended fluctuation analysis slope 2; MSE 1∼5, the summation of entropy values of scales 1 to 5; MSE 6∼20, the summation of entropy values of scales 6 to 20; MSE slope 5, the linear-fitted slope of scales 1 to 5; SD1, Poincaré plot standard deviation perpendicular the line of identity; SD2, Poincaré plot standard deviation along the line of identity; SD1/SD2, SD1-to-SD2 ratio; SampEn, sample entropy; *: p < 0.05 versus < 1 year pre-PVI; +: p < 0.05 versus 1∼3 months post-PVI Open table in a new tab

PO-04-206 THE TRANSFERABLE ARTIFICIAL INTELLIGENT MODEL BASED ON ELECTROCARDIOGRAM: A PROSPECTIVE OBSERVATIONAL STUDY TOWARD HOME-BASED APPLICATION OF SINGLE-LEAD ECG IN IDENTIFYING HEART FAILURE WITH LOW LEFT VENTRICULAR EJECTION FRACTION

Although heart failure with reduced ejection fraction (HFrEF) can benefit from treatment, it remains underdiagnosed due to the limited accessibility of echocardiography. Several studies have shown that artificial intelligent (AI) models of 12 leads ECG can successfully identify ventricular dysfunction. However, such models are hard to deploy for frequent surveillance of the left ventricular ejection fraction (LVEF), especially under the home-based scenario. We aimed to design a prospective study that used a single-lead 30-second ECG recorded and operated by patients to transfer and test an AI model constructed with convolutional neural network (CNN) analysis of standard 12-lead ECG from a retrospective single medical center cohort. In addition, we also try to leverage the short-term heart rate variability (HRV) to improve the sensitivity and specificity of the model. The 12-lead ECGs of sinus rhythm with LVEF measuring within 90 days of the recording date were included. The dataset was split into training and validation sets at a ratio of 7:3 without patient overlapping. To select feasible models of single-lead ECG for identifying LVEF of 45% or lower, we trained the CNN models using single-lead ECG recorded from each lead placement as input. The models with the top 3 performances were transferred to the corresponding lead of the single-lead ECG datasets acquired prospectively to validate their generalizability. Among all single-lead ECG models trained from 56479 recordings of 33010 patients, the AUC of the top 3 ranked models (lead aVR, I, and V5) were 0.89, 0.88, and 0.88, respectively. While aVR is impossible to derive from single-lead placement, we applied the models of lead I, V5, and lead II instead. For the prospective single-lead ECG datasets, 144 patients with an average age of 64 years old were recruited, and the models were tested. No significant drop in the performance of the lead I model was shown (AUC=0.88). Furthermore, adding HRV to the lead I model can improve overall accuracy (AUC=0.92) and sensitivity and specificity of the optimal cutting threshold. With the assistance of AI algorithm, single-lead ECG recorded and operated by patients from a wristband performed well in detecting low LVEF of 45% or lower. This simple approach can provide an inexpensive and convenient tool for the home-based monitoring of LVEF, and the tool's effectiveness warrants further study.

Effect of ageing on the cardiac activity of the small primate Microcebus murinus

Age is an important factor of comorbidity in the development of cardiovascular diseases. Regardless of lifestyle, aged people suffer from maximal heart rate (HR) and HR variability (HRV) decrease that could impair blood circulation, tissue oxygenation and consequently self-sufficiency. Given the increase of old people in modern societies it is important to study the effect of ageing on the heart to treat the related consequence on the body physiology. To study the effect of aging on HR dynamics it is important to use appropriate animal models that could replicate the cardiac physiology, but also the neural environment that modulates HR in aged patients. The small primate Microcebus murinus, also known as gray mouse lemur (ML), responds to these criteria. Indeed, differently from mice it spontaneously develops neurodegenerative diseases. In addition, although ML lies in between the size of mice and rats, it can live up to 12 years in captivity, generating about 3 billion heartbeats in a lifetime. Thus, ML generates as many heartbeats as humans in a lifetime and about three times more than mice. To study HR and HRV in ML, we used a mini Holter and we developed a jacket to record surface electrocardiograms (ECGs) in young (1–5 years) and aged (6–10 years) animals of both genders. These experiments showed HR decrease in correlation with age in male MLs, but not in females. To get insights on the sympathetic tone of ML, we measured the coefficient of variability of the interval between two heartbeats (CVRR). Under handling stress, we found higher CVRR in aged versus young ML males, indicative of lower sympathetic tone. Conversely, the index of short-term HRV, related to parasympathetic modulation (RMSSD), showed no difference in response to stress in young and aged MLs of both genders. Next, we measured the concentration of adrenaline and noradrenaline in the urines of ML of different age and both genders. Accordingly, with our measurements of HRV we found a tendency of decrease in the urine concentration of noradrenaline in aged versus young ML males. Our preliminary results suggest that age impairs the autonomic regulation of HR, but this effect is evident in aged ML males and not in females.

Electromagnetic Fields - Do They Pose a Cardiovascular Risk?

Mobile wireless communication technologies have now become an everyday part of our lives, 24 hours a day, 7 days a week. Monitoring the autonomous system under exposition to electromagnetic fields may play an important role in broading of our still limited knowledge on their effect on human body. Thus, we studied the interaction of the high frequency electromagnetic field (HF EMF) with living body and its effect on the autonomic control of heart rate using Heart Rate Variability (HRV) linear and nonlinear analyses in healthy volunteers. A group of young healthy probands (n=30, age mean: 24.2 ± 3.5 years) without any symptoms of disease was exposed to EMF with f=2400 MHz (Wi Fi), and f=2600 MHz (4G) for 5 minutes applied on the chest area. The short-term heart rate variability (HRV) metrics were used as an indicator of complex cardiac autonomic control. The evaluated HRV parameters: RR interval (ms), high frequency spectral power (HF-HRV in [ln(ms2)]) as an index of cardiovagal control, and a symbolic dynamic index of 0V %, indicating cardiac sympathetic activity. The cardiac-linked parasympathetic index HF-HRV was significantly reduced (p =0.036) and sympathetically mediated HRV index 0V % was significantly higher (p=0.002) during EMF exposure at 2400 MHz (Wi-Fi), compared to simulated 4G frequency 2600 MHz. No significant differences were found in the RR intervals. Our results revealed a shift in cardiac autonomic regulation towards sympathetic overactivity and parasympathetic underactivity indexed by HRV parameters during EMF exposure in young healthy persons. It seems that HF EMF exposure results in abnormal complex cardiac autonomic regulatory integrity which may be associated with higher risk of later cardiovascular complications already in healthy probands.

Cardiac Rhythms and Variation in Hibernating Arctic Ground Squirrels.

AbstractThe dramatic decrease in heart rate (HR) during entrance into hibernation is not a mere response to the lowering of core body temperature (Tb) but a highly regulated fall, as the decrease in HR precedes the drop in Tb. This regulated fall in HR is thought to be mediated by increased cardiac parasympathetic activity. Conversely, the sympathetic nervous system is thought to drive the increase of HR during arousal. Despite this general understanding, we lack temporal information on cardiac parasympathetic regulation throughout a complete hibernation bout. The goal of this study was to fill this gap in knowledge by using Arctic ground squirrels implanted with electrocardiogram/temperature telemetry transmitters. Short-term HR variability (root mean square of successive differences [RMSSD]), an indirect measure of cardiac parasympathetic regulation, was calculated in 11 Arctic ground squirrels. RMSSD, normalized as RMSSD/RR interval (RRI), increased fourfold during early entrance (from to , ). RMSSD/RRI peaked after HR dropped by over 90% and Tb fell by 70%. Late entrance was delineated by a decline in RMSSD/RRI while Tb continued to decrease. During arousal, HR started to increase 2 h before Tb, with a concurrent decrease in RMSSD/RRI to a new minimum. As Tb increased to a maximum during interbout arousal, HR declined, and RMSSD/RRI increased. These data suggest that activation of the parasympathetic nervous system initiates and regulates the HR decrease during entrance into hibernation and that withdrawal of parasympathetic activation initiates arousal. We conclude that cardiac parasympathetic regulation persists throughout all phases of a hibernation bout-a feature of the autonomic nervous system's regulation of hibernation that was not appreciated previously.

CONSEQUENCES OF BRISK WALK, MODERATE INTENSITY CONTINUOUS AND HIGH INTENSITY INTERVAL TRAINING ON SHORT-TERM HEART RATE VARIABILITY IN HEALTHY YOUNG ADULTS

Background: Short term heart rate variability is a time saving non-invasive measure of autonomic nervous system dysfunction. This study was conducted to assess and compare the effect of walking, medium intensity continuous and high-intensity interval training exercise modalities on short-term heart rate variability. Methods: This experimental study was conducted at the Department of Physiology, Islamic International Medical College, Rawalpindi, from August 2018 to August 2019. A total of 31 non-obese, healthy young individuals, free of comorbidities were included in the study. Participants were assigned through randomization to walk for 30 minutes intervention (n=10), medium intensity continuous training (MICT) intervention (n=11) and high-intensity interval training (HIIT) intervention (n=10). Intervention groups completed a total of 24 sessions in 7 weeks. Heart rate variability (HRV) analysis was performed by a 15-minute ECG recording before and after 24 sessions of intervention. ECGs were recorded by using the PowerLab® model 4/25T and the data were analysed using the software LabChart® Pro-8.0 with HRV 2.0 module installed. Results: After 24 sessions of 30-minute brisk walking exercise of 3,000 steps in an open area revealed a significant improvement in some HRV components when compared with pre-intervention levels of mean R-R interval (p=0.02), LFms2 (p=0.02) and LF/HF ratio (p=0.03). No significant differences were recorded after MICT and HIIT interventions among the groups. Conclusion: Compared to MICT and HIIT, a brisk walk in an open area was found to be effective mode of physical activity for improvement of HRV. Pak J Physiol 2023;19(1):21–5

Heart rate variability in patients presenting with anginal symptoms in absence of cardiac and other diseases

Objectives: Angina is a symptom of coronary artery disease (CAD). Modulation of cardiac autonomic tone as assessed by heart rate (HR) variability (HRV) is found reduced in patients with CAD; myocardial ischemia, myocardial infarction and some other cardiovascular diseases. Reduced HRV has been found associated with sudden cardiac death in these CAD patients. Several patients present with anginal symptoms clinically in absence of CAD or other diseases. The status of HRV is not much clear in these patients. Thus, we aimed to assess HRV in patients with angina with and without myocardial ischemia and compare it with HRV of healthy subjects of similar age groups and follow-up patients for 1 year for cardiac/health events. Materials and Methods: The study included 61 consecutive male patients clinically presenting with angina and 30 healthy subjects. Based on Thallium-201 myocardial perfusion Single-photon emission computerized tomography (SPECT) imaging, patients were divided into two groups; patients with myocardial perfusion defects (MPD), (n = 33, age 54.91 ± 7.43 years) and patients with no MPD (NMPD), NMPD (n = 28, age 53.04 ± 8.50 years). Short-term HRV was assessed in all patients and subjects in resting supine position following standard protocol. All MPD and 25 NMPD patients could be followed up for 1 year for cardiac/health events. Results: Surprisingly, the NMPD patients showed significantly reduced HRV, Standard deviation of the N-N intervals, The square root of the mean squared differences of successive N-N intervals, Percentage of the number of interval differences of successive N-N intervals greater than &gt;50 ms divided by total number of R-R intervals, low frequency (LF) power, High Frequency (HF) power and total power as compared to both MPD patients and healthy subjects. (Total power [NMPD vs. MPD]: 610.1 [379.9–1072.8] vs. 1508.0 [748.4–2339.4] millisecond squares (ms2), P = 0.001), healthy subjects (Total power: 1414.6 [1104.6-2141.5] ms2, P = 0.001). The markers of sympathetic tone; LF (normalised unit) and LF/HF ratio were higher in NMPD patients as compared to MPD patients resulting in an altered sympathovagal balance. During a 1-year follow-up, sudden death was seen in one MPD patient (3.1%) and two NMPD patients (8%). Conclusion: The NMPD patients showed significantly reduced HRV as compared to both MPD patients and Healthy subjects with an altered sympathovagal balance. Sudden death was also seen in NMPD patients as MPD patients.

Heart rate variability modifications in adult patients with early versus late-onset temporal lobe epilepsy: A comparative observational study

ObjectivesTemporal lobe epilepsy (TLE) is the most frequent form of focal epilepsy. TLE is associated with cardio-autonomic dysfunction and increased cardiovascular (CV) risk in patients over the fifth decade of age. In these subjects, TLE can be classified as early-onset (EOTLE; i.e., patients who had developed epilepsy in their youth) and late-onset (LOTLE; i.e., patients who developed epilepsy in adulthood). Heart rate variability (HRV) analysis is useful for assessing cardio-autonomic function and identifying patients with increased CV risk. This study compared changes in HRV occurring in patients over the age of 50, with EOTLE or LOTLE. MethodsWe enrolled twenty-seven adults with LOTLE and 23 with EOTLE. Each patient underwent a EEG and EKG recording during 20-minutes of resting state and a 5-minutes hyperventilation (HV). Short-term HRV analysis was performed both in time and frequency domains. Linear Mixed Models (LMM) were used to analyze HRV parameters according to the condition (baseline and HV) and group (LOTLE and EOTLE groups). ResultsCompared to the LOTLE group, the EOTLE group showed significantly decreased LnRMSSD (natural logarithm of the root mean square of the difference between contiguous RR intervals) (p-value=0.05), LnHF ms2 (natural logarithm of high frequency absolute power) (p-value=0.05), HF n.u. (high frequency power expressed in normalized units) (p-value=0.008) and HF% (high frequency power expressed in percentage) (p-value=0.01). In addition, EOTLE patients exhibited increased LF n.u. (low frequency power expressed in normalized units) (p-value=0.008) and LF/HF (low frequency/high frequency) ratio (p-value=0.007). During HV, the LOTLE group exhibited a multiplicative effect for the interaction between group and condition with increased LF n.u. (p = 0.003) and LF% (low frequency expressed in percentage) (p = 0.05) values. ConclusionsEOTLE is associated with reduced vagal tone compared to LOTLE. Patients with EOTLE may have a higher risk of developing cardiac dysfunction or cardiac arrhythmia than LOTLE patients.

Performance of heart rate adjusted heart rate variability for risk stratification of sudden cardiac death

PurposeAs a non-invasive tool for the assessment of cardiovascular autonomic function, the predictive value of heart rate variability (HRV) for sudden cardiac death (SCD) risk stratification remains unclear. In this study, we investigated the performance of the individualized heart rate (HR) adjusted HRV (HRVI) for SCD risk stratification in subjects with diverse risks.MethodsA total of 11 commonly used HRV metrics were analyzed in 192 subjects, including 88 healthy controls (low risk group), 82 hypertrophic cardiomyopathy (HCM) patients (medium risk group), and 22 SCD victims (high risk group). The relationship between HRV metrics and HR was examined with long-term and short-term analysis. The performance HRVI was evaluated by area under the receiver operating characteristic curve (AUC) and covariance of variation (CV).ResultsMost of the HRV metrics were exponentially decayed with the increase of HR, while the exponential power coefficients were significantly different among groups. The HRVI metrics discriminated low, medium and high risk subjects with a median AUC of 0.72[0.11], which was considerably higher than that of the traditional long-term (0.63[0.04]) and short-term (0.58[0.05]) HRV without adjustment. The average CV of the HRVI metrics was also significantly lower than traditional short-term HRV metrics (0.09 ± 0.02 vs. 0.24 ± 0.13, p < 0.01).ConclusionsSubjects with diverse risks of SCD had similar exponential decay relationship between HRV metrics and HR, but with different decaying rates. HRVI provides reliable and robust estimation for risk stratification of SCD.

ECG-Based Semi-Supervised Anomaly Detection for Early Detection and Monitoring of Epileptic Seizures

Epilepsy is one of the most common brain diseases, characterized by frequent recurrent seizures or "ictal" states. A patient experiences uncontrollable muscular contractions, inducing loss of mobility and balance, which may result in injury or even death during these ictal states. Extensive investigation is vital to establish a systematic approach for predicting and informing patients about oncoming seizures ahead of time. Most methodologies developed are focused on the detection of abnormalities using mostly electroencephalogram (EEG) recordings. In this regard, research has indicated that certain pre-ictal alterations in the Autonomic Nervous System (ANS) can be detected in patient electrocardiogram (ECG) signals. The latter could potentially provide the basis for a robust seizure prediction approach. The recently proposed ECG-based seizure warning systems utilize machine learning models to classify a patient's condition. Such approaches require the incorporation of large, diverse, and thoroughly annotated ECG datasets, limiting their application potential. In this work, we investigate anomaly detection models in a patient-specific context with low supervision requirements. Specifically, we consider One-Class SVM (OCSVM), Minimum Covariance Determinant (MCD) Estimator, and Local Outlier Factor (LOF) models to quantify the novelty or abnormality of pre-ictal short-term (2-3 min) Heart Rate Variability (HRV) features of patients, trained on a reference interval considered to contain stable heart rate as the only form of supervision. Our models are evaluated against labels that were either hand-picked or automatically generated (weak labels) by a two-phase clustering procedure for samples of the "Post-Ictal Heart Rate Oscillations in Partial Epilepsy" (PIHROPE) dataset recorded by the Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, achieving detection in 9 out of 10 cases, with average AUCs of over 93% across all models and warning times ranging from 6 to 30 min prior to seizure. The proposed anomaly detection and monitoring approach can potentially pave the way for early detection and warning of seizure incidents based on body sensor inputs.

Validity and Reliability of Short-Term Heart Rate Variability Parameters in Older People in Response to Physical Exercise.

Currently, and to the best of our knowledge, there is no standardized protocol to measure the effect of low- to moderate-intensity physical exercise on autonomic modulation focused in older people. Validate a test-retest short-term exercise protocol for measuring the autonomic response through HRV in older people. A test-retest study design was used. The participants were selected through intentional non-probabilistic sampling. A total of 105 older people (male: 21.9%; female: 78.1%) were recruited from a local community. The assessment protocol evaluated HRV before and immediately after the 2-min step test. It was performed twice on the same day, considering a time of three chronological hours between the two measurements. The posterior distribution of estimated responses in the Bayesian framework suggests moderate to strong evidence favoring a null effect between measurements. In addition, there was moderate to robust agreement between heart rate variability (HRV) indices and assessments, except for low frequency and very low frequency, which showed weak agreement. Our results provide moderate to strong evidence for using HRV to measure cardiac autonomic response to moderate exercise, suggesting that it is sufficiently reliable to show similar results to those shown in this test-retest protocol.

Alterations in heart rate variability and pro-inflammatory cytokine TNF-alpha in individuals with panic disorder

Based on the autonomic flexibility–neurovisceral integration model, panic disorder (PD) has been associated with a generalized proinflammatory state and lower cardiac vagal tone. The heart rate variability (HRV) provides an index of cardiac autonomic function and reflects the parasympathetic innervation to the heart regulated by the vagus nerve. The aim of this study was to explore the heart rate variability, pro-inflammatory cytokines and their associations in individuals with PD. Short-term HRV with time and frequency domain indices as well as pro-inflammatory cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha) were assessed in seventy individuals with PD (mean age: 35.64 ± 14.21 years) and thirty-three healthy controls (mean age: 38.33 ± 14.14 years). Individuals with PD showed significantly lower HRV in the time and frequency domain parameters during a short-term resting condition. A lower TNF-alpha concentration could be observed in individuals with PD in comparison to healthy controls, but no differences in IL-6. Furthermore, the HRV parameter absolute power in the low-frequency band 0.04–0.15 Hz (LF) predicted TNF-alpha concentrations. In conclusion, a lower cardiac vagal tone, decreased adaptive autonomic nervous system (ANS), and higher pro-inflammatory cytokine state could be observed in individuals with PD compared to healthy controls.

Heart Rate Asymmetry in Healthy Children.

Heart rate asymmetry (HRA) is a physiological phenomenon characterized by an unequal contribution of heart rate decelerations and accelerations to different heart rate variability (HRV) features. While HRA has been demonstrated in adults' ECGs of different duration, a similar investigation in healthy children has not been conducted. This study investigated the variance- and number-based HRA features in 96 healthy children (50 girls and 46 boys, aged 3-18 years) using 24-h ECGs. Additionally, we studied sex differences in HRA. To quantify HRA, variance-based and relative contributions of heart rate decelerations to short-term (C1d), long-term (C2d), and total (CTd) HRV, and the number of all heartbeats (Nd) were computed. Heart rate decelerations contributed more to C1d, but less to C2d and CTd, and were less frequent than heart rate accelerations. Short-term HRA was better expressed in boys. The majority of children (93.7%) had short-term HRA, 88.5% had long-term HRA, 88.5% had total HRA, and 99.0% had more accelerations than decelerations. No sex differences were observed for the rate of various HRA features. Heart rate asymmetry is a common phenomenon in healthy children, as observed in 24-h ECGs. Our findings can be used as reference data for future clinical studies on HRA in children.

Altered baroreflex sensitivity at rest and during Valsalva maneuver in healthy male offspring of hypertensive patients

A family history of hypertension puts young adults at a higher risk of developing hypertension, that too, at an earlier age than their parents. Recent studies suggest that the baroreflex mechanism, which takes care of the short-term regulation of blood pressure (BP), also plays a role in the long-term regulation of BP. Studies have reported decreased baroreflex sensitivity (BRS) in hypertensives. Reduced BRS is shown to herald the future occurrence of cardiovascular diseases (CVD) and helps in risk stratification AIM: Toassess BRS at rest and during the Valsalva maneuver among apparently healthy male offspring (age 18-35 years) of hypertensive patients. We recruited 37 participants whose parents (either/both) were hypertensive in the study group and whose parents (both) were not hypertensive in the control group. We measured basic anthropometric parameters (height, weight, waist circumference), cardiovascular parameters (heart rate and BP), short-term heart rate variability, and BRS (at rest and during Valsalva). We found that BRS at rest and BRS during the Valsalva maneuver were reduced among healthy male offspring of hypertensive parents than in healthy male offspring of non-hypertensive parents. Further, HRV indices and Valsalva ratio showed a sympathovagal imbalance in the form of decreased vagal and increased sympathetic activity. The reduced BRS and sympathovagal imbalance in male offspring of hypertensive parents reveal the early risk of developing hypertension in the future.

Heart Rate Variability at Rest Predicts Heart Response to Simulated Diving.

A characteristic feature of the cardiac response to diving is the uncertainty in predicting individual course. The aim of the study was to determine whether resting regulatory heart rate determinants assessed before diving may be predictors of cardiac response in a simulated diving test. The research was conducted with 65 healthy volunteers (37 women and 28 men) with an average age of 21.13 years (20-27 years) and a BMI of 21.49 kg/m2 (16.60-28.98). The simulated diving test consisted of stopping breathing after maximum inhaling and voluntarily immersing the face in water (8-10 °C) for as long as possible. The measurements included heart rate variability (HRV) analysis before diving and determination of the course of the cardiac response to diving-minimum and maximum heart rate (HR). The results indicate that minimum HR during diving (MIN_div) is dependent on the short-term HRV measures, which proves the strong influence of the parasympathetic system on the MIN_div. The lack of dependence of MIN_div on short-term HRV in women may be associated with differences in neurogenic HR regulation in women and men. In conclusion, cardiac response to simulated diving is strictly dependent on the autonomic regulation of the heart rhythm under resting conditions. The course of the cardiac response to diving and its relationship with resting HRV appears to be gender dependent.

Normative values of resting heart rate variability in young male contact sport athletes: Reference values for the assessment and treatment of concussion.

The objective of this study was to identify the main determinants of heart rate variability (HRV) in male athletes aged 14 to 21 years who practice competitive contact sports and to integrate these determinants with the aim of defining normative values of short-term HRV in the time and frequency domains. Participants (n = 369) were aged 14 to 21 years and included 221 football players and 148 ice hockey players. HRV was measured for 5 min at rest, and standard HRV parameters in the time and frequency domains were calculated. Heart rate (HR), age, body mass index (BMI), number of sports weekly practices (WSP) and concussion history (mTBI) were considered determinants potentially able to influence HRV. Multiple regression analysis revealed that HR was the primary determinant of standard HRV parameters. The models accounted for 13% to 55% of the total variance of HRV and the contribution of HR to this model was the strongest (β ranged from -0.34 to -0.75). HR was the only determinant that significantly contributes to all HRV parameters. To counteract this dependence, we calculated HRV corrected by the mean RR interval (RRm). Such corrections do not remove any physiological differences in HRV; they simply remove the mathematical bias. HRV parameters were therefore normalized, and their normative limits were developed relative to the mean heart rate. After correction, the correlation coefficients between HR and all corrected HRV parameters were not statistically significant and ranged from -0.001 to 0.045 (p > 0.40 for all). The automatically corrected HRV calculator, which recalculates standard HRV parameters and converts them into corrected parameters in addition to determining whether a given value is within normal limits, facilitates clinical interpretation. This study provides for the first time corrected normative values of short-term and resting state HRV parameters in competitive contact sport athletes aged 14 to 21 years. These values were developed independently of the major determinants of HRV. The baseline values for HRV parameters given here could be used in clinical practice when assessing and monitoring cerebral concussions. They may assist in decision making for a safe return to play.

Assessment of soundscapes using self-report and physiological measures

Soundscape studies evaluate the subjective and objective qualities of an environment and attempt to develop a holistic view of the interplay between the acoustic scene and the listener’s experience. Descriptors are used to express the perception of the acoustic environment, while further subjective and quantitative measures are used as indicators that represent features of the acoustic environment. The relationships between descriptors and indicators for a particular soundscape study are often identified by developing linear statistical models. This work describes an experiment to assess heart rate measures, including ultra short term heart rate variability, within the context of the predictor descriptor framework of a soundscape study. The aim of this work is to provide evidence in support of the psychophysiological basis of measures of affect in soundscape evaluation. In this study 15 participants evaluated a randomly ordered set of 8 soundscape recordings in a repeated measures directed listening experiment. Subjective evaluation of the soundscapes was performed using the self-assessment manikin and a sound classification survey. Participants’ heart rate was measured throughout the experiment with a Polar H10 ECG heart rate monitor. Statistically significant relationships were identified between indicators and descriptors that reflect results present in the literature. However, there were no significant interactions between heart rate measures and self-reported affect or classification scores. Future studies should focus on improving the selection of stimuli and the experiment methodology to boost the sensitivity of the experiment in light of small effect sizes.

Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice.

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality with an estimated 80% of SHS-related deaths attributed to cardiovascular causes. Public health measures and smoking bans have been successful both in reducing SHS exposure and improving cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a promising target for mitigating SHS exposure-induced cardiovascular outcomes. Objectives: The objectives of this study were to determine 1) effects of environmentally relevant SHS exposure on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of an sEH inhibitor (TPPU) can reduce the adverse cardiovascular effects of SHS exposure. Methods: Male C57BL/6J mice (11weeks old) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to filtered air or 3mg/m3 of SHS (6hr/d, 5d/wk) for 12weeks, followed by 4weeks of recovery in filtered air. Some mice received TPPU in drinking water (15mg/L) throughout SHS exposure. BP, heart rate (HR), HR variability (HRV), baroreflex sensitivity (BRS), and BP variability were determined monthly. Results: SHS exposure significantly decreased 1) short-term HRV by ∼20% (p < 0.05) within 4weeks; 2) overall HRV with maximum effect at 12weeks (-15%, p < 0.05); 3) pulse pressure (-8%, p < 0.05) as early as week 4; and 4) BRS with maximum effect at 12weeks (-11%, p < 0.05). Four weeks of recovery following 12weeks of SHS ameliorated all SHS-induced cardiovascular detriments. Importantly, mice exposed to TPPU in drinking water during SHS-related exposure were protected from SHS cardiovascular consequences. Discussion: The data suggest that 1) environmental relevant SHS exposure significantly alters cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be reversed by discontinuing SHS exposure; and 3) inhibiting sEH can prevent SHS-induced cardiovascular consequences.

Cardiac Autonomic Impacts of Bushfire Smoke - A Prospective Panel Study.

Air pollution is associated with cardiovascular disease and mortality. Most studies have focussed on urban or traffic-related pollution, and less is known about the impacts from bushfire smoke on cardiovascular autonomic function, although it is associated with increased sudden cardiac death and mortality. We sought to investigate its instantaneous and short-term impacts on heart rate variability (HRV). Twenty-four (24)-hour Holter electrocardiography (ECG) was repeated twice (during bushfire [Phase 1] and then clean air [Phase 2]) in 32 participants from two Australian towns (Warburton and Traralgon, Victoria) surrounding planned burning areas. This was compared with 10 control participants in another town (Maffra, Victoria) with two clean air assessments during the same periods. The primary HRV parameters assessed were those assessing overall HRV (Standard Deviation of Normal-to-Normal intervals [SDNN]), long-term HRV (Standard Deviation of the Average of Normal Sinus-to-Normal Sinus intervals for each 5-minutes [SDANN]), low frequency [LF]) and short-term HRV (Root Mean Square of Successive Differences between N-N intervals [RMSSD], High Frequency [HF], LF:HF ratio). Average concentrations of particulate matter <2.5 μm in diameter (PM2.5) were measured at fixed site monitors in each location. Mean PM2.5 levels were significantly elevated during bushfire exposure in Warburton (96.5±57.7 μg/m3 vs 4.0±1.9 μg/m3, p<0.001) and Traralgon (12.6±4.9 μg/m3 vs 3.4±3.1 μg/m3, p<0.001), while it remained low in the control town, Maffra, in each phase (4.3±3.2 μg/m3 and 3.9±3.6 μg/m3, p=0.70). Although SDANN remained stable in controls, the exposed cohort showed significant worsening in SDANN during bushfire smoke exposure by 9.6±25.7ms (p=0.039). In univariable analysis, smoke exposure was significantly associated with higher ΔSDNN and ΔSDANN (p=0.03, p=0.01 exposed vs control). The association remained significant in ΔSDANN after adjusting for age, sex and cigarette smoking (p=0.02) and of borderline significance in ΔSDNN (p=0.06). Exposure to the bushfire smoke was independently associated with reduced overall and long-term HRV. Our findings suggest that imbalance in cardiac autonomic function is a key mechanism of adverse cardiovascular effects of bushfire smoke.