Standard Deviation Of The RR Intervals Research Articles

The effect of breathing hypoxic gas (15% FIO2 ) on physiological and behavioral outcomes during simulated driving in healthy subjects.

Hypoxia is mainly caused by cardiopulmonary disease or high-altitude exposure. We used a driving simulator to investigate whether breathing hypoxic gas influences driving behaviors in healthy subjects. Fifty-two healthy subjects were recruited in this study, approved by the Science and Engineering Ethical Committee. During simulated driving experiments, driving behaviors, breathing frequency, oxygen saturation (SpO2 ), and heart rate variability (HRV) were analyzed. Each subject had four driving sessions; a 10-min practice and three 20-min randomized interventions: normoxic room air (21% FIO2 ) and medical air (21% FIO2 ) and hypoxic air (equal to 15% FIO2 ), analyzed by repeated measures ANOVA. Driving behaviors and HRV frequency domains showed no significant change. Heart rate (HR; p < 0.0001), standard deviation of the RR interval (SDRR; p = 0.03), short-term HRV (SD1; p < 0.0001), breathing rate (p = 0.01), and SpO2 (p < 0.0001) were all significantly different over the three gas interventions. Pairwise comparisons showed HR increased during hypoxic gas exposure compared to both normoxic interventions, while SDRR, SD1, breathing rate, and SpO2 were lower. Breathing hypoxic gas (15% FiO2 , equivalent to 2710 m altitude) may not have a significant impact on driving behavior in healthy subjects. Furthermore, HRV was negatively affected by hypoxic gas exposure while driving suggesting further research to investigate the impact of breathing hypoxic gas on driving performance for patients with autonomic dysfunction.

Abstract 11632: Altered Autonomic Balance Linked to Arrhythmogenicity in Chronic Myocardial Infarction Ovine Model

Background: Increased sympathetic drive resulting in decreased heart rate variability (HRV), has been linked to cardiovascular diseases such as heart failure and myocardial infarction (MI). Dynamic electrophysiological changes due to acute ischemia and chronic MI are known to be pro-arrhythmic. Objective: Evaluate the changes in autonomic tone resulting from substrate remodeling during the development of chronic MI in an in-vivo ovine model. Methods: ECG recordings were collected at baseline, post occlusion and 6 weeks post MI, in young adult sheep (n=16). Time domain, frequency domain and non-linear measures of HRV were evaluated from 10 minutes of ECG data at the 3 time points. RR interval, heart rate, SDRR (standard deviation of the RR intervals), RMSSD (root mean square of successive differences between normal heartbeats), QTc interval, pNN 50 , LF/HF ratio and SD1/SD2 ratio were calculated and compared between baseline, post acute coronary artery occlusion and after 6 weeks of chronic MI. 24-hour telemetry was also performed in an ambulatory animal for 6 weeks to monitor the progression of alterations in the T-wave morphology or duration, i.e. T-wave alternans, a known marker of ventricular tachyarrhythmias, with chronic MI. Results: Chronic MI led to significantly decreased RR interval (Fig.1A) and increased heart rate (Fig.1B), along with a significant prolongation of the QTc interval (Fig.1C). Significant rise was also observed in the SDRR (Fig1D) and LF/HF ratio (Fig1E) indicating a shift towards increased sympathetic tone and reduced parasympathetic drive. In addition to the autonomic changes, a significant rise in T-wave alternans burden (Fig1F) and localized action potential alternans inducibility was observed with progression of MI indicating increased arrhythmogenicity. Conclusion: Skewed autonomic balance is evident in chronic MI and may be closely linked to increased arrhythmogenicity.

Effects of Cognitive Demand Levels for Various Horticultural Activities on Psychophysiological Responses in Adults

We compared the effects of horticultural activities according to cognitive demand levels on psychophysiological responses in adults. Thirty-two adults in their 20s were included. Participants performed 10 horticultural activities (raking, planting transplants, fertilizing, tying plants to stakes, harvesting, sowing, conducting cuttage, planting potted plants, cutting and washing, arranging flowers) for 150 seconds at two levels of cognitive demand. Electroencephalographic (EEG) and electrocardiographic measurements were acquired during the activity. After each activity, the participants’ emotional states were evaluated using the semantic differential method (SDM). The EEG results, according to comparison by activity, showed that for nine activities, excluding raking, relative theta decreased when performing tasks at a level of high cognitive difficulty (HCD) compared with those with a low cognitive difficulty (LCD), and relative beta, relative gamma, fast alpha, and relative low beta increased, indicating activation of the prefrontal cortex. In the relative theta power spectra, the cuttage activity was found to be the lowest when performing tasks at a high level high cognitive difficulty, and the working memory function was activated the most compared with other activities. When sowing at a low level of cognitive demand, participants’ heart rate decreased and stabilized. When potted plants were harvested at a high level of cognitive difficulty, the ratio of low frequency to high frequency increased, and the sympathetic nervous system was activated. In addition, when planting transplants, and cutting and washing were performed at a high level of cognitive difficulty, and the standard deviation of the RR interval was high, indicating a high ability of the autonomic nervous system to resist stress. As a result of the SDM, the emotional state according to task difficulty was found to be more stable and relaxed than high cognitive difficulty, but a significant increase in comfort, relaxation, and naturalness was achieved when nine gardening tasks with low cognitive difficulty were performed, with the exception of sowing. The results of this study show that tasks with high cognitive difficulty activate working memory, whereas those with low cognitive difficulty stabilize and relax brain activation. Therefore, this study confirmed that an intervention in horticultural activities with an appropriate level of cognitive difficulty could have a significant effect on psychophysiological changes in adults.

Heart Rate Variability in Unexplained Syncope Patients Versus Healthy Controls: A Comparative Study.

Background Syncope or fainting is the sudden and transient loss of consciousness. This could lead to an increase in mortality due to sudden cardiac death or comorbidity in these patients. Heart rate variability (HRV) is a noninvasive bedside procedure for assessing the cardiovascular autonomic function. There may be an abnormal alteration in the HRV parameters in syncope patients. This can be used for looking into cardiovascular autonomic changes in syncope. This would help in early diagnosis and intervention. Objective The aim of this present study was to compare the HRV parameters betweenunexplained syncope patients andage-matched healthy controls and to find a correlation between HRV parameters and cardiovascular parameters like pulse and mean blood pressure. Materials and methods A five-minute continuous electrocardiogram (ECG) was recorded and HRV analysis was done by ADInstruments' PowerLab (Oxford, United Kingdom) for 25 cases and 25 controls. Results The mean standard deviation of the RR interval (SDRR) in millisecondswas found to be significantly lower in the cases (21.93 ± 3.53) as compared to controls (71.27 ± 27.40). The mean value of the low-frequency to high-frequency ratio (LF/HF) was significantly higher in cases (1.43 ± 0.40) as compared to controls (0.98 ± 1.07). However, there was no significant correlation between the pulse, blood pressure, and HRV measures. Conclusion The findings suggest a sympathetic predominance in the cases of unexplained syncope as compared to the controls.

The Validity of Heart Rate Variability Obtained from Electrocardiography and Blood Pressure in Rats Subjected to Isoproterenol-Induced Heart Ischemia.

Heart rate variability (HRV) is calculated by electrocardiography (ECG-HRV) or blood pressure (BP-HRV). The purpose of this study was to determine the validity of the above methods in rats with normal and ischemic hearts during the baroreflex maneuver. The study was conducted at Shiraz University of Medical Sciences, Shiraz, Iran, in 2021. Sprague-Dawley rats were divided into a sham group and an isoproterenol-mediated cardiac ischemia (ISO) group. Saline and isoproterenol (150 mg/kg) injected subcutaneously for 2 consecutive days in the sham and ISO groups, respectively. Then, the animals were anesthetized with an intraperitoneal injection of sodium thiopental (60 mg/kg), and the femoral artery and vein were cannulated. Baroreflex was activated using an intravenous injection of phenylephrine (10 μg/100 μL saline). ECG, BP, and heart rate (HR) were recorded, and the time domain of HRV and baroreflex gain were calculated. Baroreflex gain in the ISO group (male, weight=275.8±2.8 g, n=8) was lower than that in the sham group (male, weight=258±2.3 g, n=8) (P<0.05). ECG-HRV indicated an increase in the standard deviation of the RR interval (SDRR), the index of overall HRV, and the parasympathetic index of the root mean square of successive differences (RMSSD) in both groups. However, the rise in SDRR and RMSSD in the ISO group was less than that in the sham group (P<0.05). SDRR and RMSSD obtained from BP did not show a difference between the sham and ISO groups, nor did they correspond with the results seen in baroreflex gain. BP-HRV was not as valuable as ECG-HRV in assessing cardiac ischemia.

Heart rate variability modification as a predictive factor of sudden unexpected death in epilepsy: How far are we? A systematic review and meta-analysis.

Sudden unexpected death in epilepsy (SUDEP) is a sudden, unexpected death in people with epilepsy, with or without evidence of an epileptic seizure. The pathophysiological mechanism underlying SUDEP appears to be partly associated with an autonomic nervous system (ANS) dysfunction. Heart rate variability (HRV) analysis is a reliable, non-invasive method for detecting fluctuations in the ANS. In this systematic review we analyzed the data available in the literature on changes in HRV parameters in patients with SUDEP. We carried out a systematic search of the literature to identify the quantitative variations of HRV in epileptic patients with SUDEP. The following databases were used: Pubmed, Google Scholar, EMBASE, and CrossRef. A pooled analysis was carried out, and the results obtained were compared using mean difference (MD). The review was registered on the PROSPERO platform (CRD42021291586). Seven articles were included, with a total of 72 SUDEP cases associated with altered HRV parameters. Generally, a reduction of SDNN (standard deviation of the RR intervals) and RMSSD (root mean square differences of successive RR intervals) was reported in most SUDEP patients. According to MD, the SUDEP patients showed no differences in time and frequency domain parameters compared to controls. However, a trend toward increased low frequency and high frequency ratio (LF/HF) was observed in the SUDEP patients. HRV analysis is a valuable method for assessing cardiovascular risk and cardioautonomic impairment. Although a possible association between HRV variation and SUDEP has been reported, further studies are needed to assess the potential role of HRV modifications as a SUDEP biomarker.

Effects of levetiracetam treatment on autonomic nervous system functions in pediatric epilepsy patients.

This study investigated the effects of levetiracetam (LEV) treatment on cardiac rhythm and heart rate variability. The study included two groups of patients diagnosed with non-lesional epilepsy who had not yet been treated and who presented to the outpatient pediatric neurology clinic at Van Training and Research Hospital, Van, Turkey, between 2019 and 2020. The heart rate variability (HRV) of 47 patients in the first group, before and at the 3rd month of treatment, and intravenous (IV) LEV loading in 13 patients in the second group was evaluated by Holter electrocardiography (ECG). It was determined that the values of triangular index, standard deviation of the RR intervals over a 24-hour period (SDNN), standard deviation of all 5-minute mean RR intervals (SDANN), mean of standard deviations of all normal RR intervals (SDNNI), the percentage of RR intervals with >50-millisecond variation (PNN50), and the square root of mean squared differences of successive RR intervals (RMSSD). HRV of 47 patients under LEV treatment significantly increased in the 3rd month of treatment compared to baseline (p < 0.05). No difference was found in HRV between the intravenous loading and the control group (p > 0.05). Our study suggests that the sympathovagal balance before treatment in the patient group is in favor of the sympathetic nervous system and that the sympathovagal imbalance improves after treatment. Our results show that LEV monotherapy and loading have no negative effect on HRV and potential cardiac arrhythmia risk in children with epilepsy.

Proposal for a fuzzy logic-based system to determine cardiovascular risk

&lt;span lang="EN-US"&gt;One of the key variables to determine the level of cardiovascular risk is the heart rate variability, which associates different metrics such as average of the RR intervals (average RR), standard deviation of the RR intervals (SDRR) and percentage of differences greater than 50 ms in RR intervals (pRR50). Given that these metrics make use of different measurement units, scales, and ranges, it is necessary to determine an output risk level in intelligible terms, taking as input the values of each one of them. Thus, this article proposes the development of a system based on fuzzy logic to determine the percentage or cardiovascular risk level. The fuzzy system is connected to an Arduino board with a heart rate sensor where the heart rate and heart rate variability values are obtained, so they are used to calculate the risk level metrics. Using the input values of each metric, as well as the 3 membership functions of the inputs, the output membership function, and a total of 18 inference rules defined from the inputs and outputs, the system obtains the output cardiovascular risk level. The fuzzy system was implemented using free hardware and software tools, making it available in medical campaigns for the early identification of heart conditions.&lt;/span&gt;

Autonomic nervous system responses of dogs to human-dog interaction videos

We examined whether dogs show emotional response to social stimuli played on videos. Secondary, we hypothesized that if dogs recognize themselves in videos, they will show a different emotional response to videos of self and other dogs. We compared heart rate variability among four video stimuli: a video of the owner ignoring another dog (OW-A-IGN), a video of a non-owner interacting with another dog (NOW-A-INT), a video of the owner interacting with another dog (OW-A-INT), and a video of the owner interacting with the dog subject (OW-S-INT). The results showed that root mean square of the difference between adjacent R-R Intervals (RMSSD) and standard deviation of the R-R Interval (SDNN) were lower in NOW-A-INT and OW-S-INT than in OW-A-IGN. There was no statistical difference in the responses to OW-S-INT and OW-A-INT, suggesting that dogs did not distinguish themselves and other dogs in videos. On the other hand, the difference in mean R-R Interval between OW-S-INT and OW-A-INT showed positive correlation with the score of attachment or attention-seeking behavior. Therefore, this study does not completely rule out self-recognition in dogs and there remains the possibility that the more attached a dog to its owner, the more distinct the dog's emotional response to the difference between the self-video stimulus and the video stimulus of another dog. Further studies are needed to clarify this possibility.

Psychophysiological Responses of Adults According to Cognitive Demand Levels for Horticultural Activities

We aimed to compare psychophysiological responses in adults according to cognitive demand levels for horticultural activities to confirm the feasibility of horticultural activity for improving attention and emotional states. A total of 60 adults in their 20s were included in this crossover design study. Participants performed soil-mixing activities with 2 cognitive demand levels for 2 min each. Electroencephalography (EEG) and electrocardiography (ECG) were performed during these activities. After each activity, the semantic differential method (SDM) was used to evaluate the emotional states of the participants. EEG results revealed that relative fast alpha and low beta power spectrums in the frontal lobes were high during the activity with high cognitive demand compared to those during the low demand activity, which indicates activation in the prefrontal cortex. ECG results showed that during the high cognitive demand activity, the standard deviation of the RR intervals of male adults was high, indicating a high-stress resistance ability of the autonomic nervous system. However, as a result of the SDM, there were no significant differences in emotional states according to the level of activity difficulty. Therefore, this study confirmed the possibility that the intervention of horticultural activities of an appropriate difficulty did not negatively affect subjective emotional changes and could have a positive effect on the improvement of attention levels and emotional stability in adults.

Cardiac Autonomic Dysfunction Is Associated With Risk of Diabetic Kidney Disease Progression in Type 2 Diabetes Mellitus.

BackgroundEvidence on the relationship between heart rate variability (HRV) and albumin-to-creatinine ratio (ACR) combined with estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes mellitus (T2DM) is rare. Thus, this study aimed to investigate the relationship between heart rate variability and the risk of diabetic kidney disease (DKD) progression in diabetes patients.MethodOverall, 747 T2DM patients who were admitted to the Second Affiliated Hospital of Nanchang University underwent 24-hour dynamic electrocardiograms for HRV analysis. Time-domain HRV measures included mean heart rate, standard deviation of the R-R interval (SDNN), SDNN index, root mean squared difference of successive RR intervals (RMSSD), and percent of adjacent RR intervals with a difference greater than 50 ms (PNN50). Frequency-domain measures included low frequency (LF), very low frequency (VLF), high frequency (HF) components and LF-to-HF ratio. The risk of DKD progression was determined by combining ACR and eGFR and stratified as low risk (Group A), moderately increased risk (Group B), high risk (Group C), and very high risk (Group D) based on the Kidney Disease: Improving Global Outcomes guidelines.ResultThere were significant differences in HRV parameters among the four risk groups (SDNN: 113 ms vs 109 ms vs 101 ms vs 81 ms, P<0.01; LF: 240.2 ms2 vs 241.1 ms2 vs 155.2 ms2 vs 141.9 ms2, P<0.01; LF-to-HF ratio: 1.70 vs 1.24 vs 1.12 vs 0.93, P<0.01; VLF: 723.7 ms2 vs 601.1 ms2 vs 446.4 ms2 vs 356.3 ms2, P<0.01). A very high risk of DKD progression was significantly associated with a lower SDNN (β=-19.5, 95% CI: -30.0 to -10.0, P<0.01), and moderately increased, high, and very high risks were associated with lower LF-to-HF ratio and VLF (P<0.05). Logistic regression analysis showed that group D had a higher risk of reduced SDNN, LF-to-HF ratio, and VLF compared with group A after adjusting for systolic blood pressure, glycated haemoglobin, haemoglobin, high-density lipoprotein cholesterol, and age (odds ratio (95% CI): 0.989 (0. 983–0.996), 0.674 (0.498–0.913), and 0.999 (0.999–1.000), respectively).ConclusionCardiac autonomic dysfunction is associated with a risk of DKD progression in adults with T2DM, and reduced heart rate variability increased such risk. Thus, HRV screening may be necessary in patients with T2DM, especially those with high proteinuria.

Complement activation mainly mediates the association of heart rate variability and cognitive impairment in adults with obstructive sleep apnea without dementia.

The relationship between autonomic nervous system dysfunction measured by heart rate variability (HRV) and cognitive impairment in obstructive sleep apnea (OSA) patients is complex and still not well understood. We aimed to analyze the role of complement activation, Alzheimer's disease (AD) biomarkers, and white matter hyperintensity (WMH) in modulating the association of HRV with cognitive performance. There were 199 subjects without dementia, including 42 healthy controls, 80 OSA patients with mild cognitive impairment (MCI), and 77 OSA patients without cognitive impairment. All participants who completed polysomnography, cognition, WMH volume, and 5-min HRV analysis were recorded during wakefulness and sleep periods. Neuron-derived exosome and astrocyte-derived exosome proteins were measured by ELISA kits. The OSA with MCI group were associated with a lower mean of standard deviations of R-R intervals for 5-min intervals (SDANN index) during wakefulness, standard deviation of the R-R interval (SDNN) during sleep stage and percentage of adjacent R-R intervals differing by more than 50 ms (PNN50) in each stage compared with OSA without MCI. The influence of HRV on cognition was partially mediated by complement activation (C5b-9 mediated a maximum of 51.21%), AD biomarkers, and WMH. Lower SDANN index and PNN50 during wakefulness and SDNN and PNN50 during sleep periods were found in OSA patients with MCI, suggesting potential vulnerability to autonomic and parasympathetic dysfunction. Complement activation, AD biomarkers, and WMH might partially mediate and interact with the influence of HRV on cognitive impairment in OSA patients. ChiCTR1900021544.

The Comparative Effect of Reduced Mindfulness-Based Stress on Heart Rate Variability among Patients with Breast Cancer.

Heart rate variability (HRV) is a powerful tool for observing interactions between the sympathetic and parasympathetic nervous systems. This study evaluated HRV during a mindfulness-based stress reduction (MBSR) program among women with breast cancer after receiving treatment. A quasi-experimental, nonrandomized design was used. Patients were allocated to usual care (n = 25) and MBSR (n = 25) groups. HRV was measured using recognized methods to assess the autonomic nervous system. Two-way ANOVA and t-tests were used to examine HRV changes between and within groups, respectively. A significant interaction effect of time with group was observed on heart rate (F (1, 96) = 4.92, p = 0.029, η2 = 0.049). A significant difference was also observed within the MBSR group preintervention and postintervention with regard to heart rate (t (24) = −3.80, p = 0.001), standard deviation of the RR interval (t (24) = 5.40, p < 0.001), root-mean-square difference in the RR interval (t (24) = 2.23, p = 0.035), and high-frequency power (t (24) = 7.73, p < 0.001). Large effect sizes for heart rate and SDNN of 0.94 and 0.85, respectively, were observed between the MBSR and usual care groups. This study provides preliminary evidence that an MBSR program may be clinically useful for facilitating parasympathetic activity associated with feelings of relaxation in treated breast cancer survivors.

Cardiac baroreflex sensitivity and heart rate variability are lower in humans with high affinity hemoglobin compared to typical affinity hemoglobin

BackgroundHumans with high O2 affinity hemoglobin (HAH) have a markedly lower partial pressure of O2at which 50% of hemoglobin is saturated (P50) and a leftward shift of the oxy‐hemoglobin dissociation curve. Humans with HAH have attenuated heart rate responses during both acute and chronic hypoxic exposure relative to humans with typical P50. Despite the attenuated heart rate responses to hypoxia, there are typically no blood pressure differences found in humans with HAH relative to humans with typical P50. Due to the blunted heart rate and normal blood pressure responses to hypoxia in humans with HAH, this study aimed to investigate the impact of HAH on cardiac autonomic function during normoxia and hypoxia. We hypothesized that humans with HAH would have lower cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV) during normoxia and hypoxia relative to individuals with typical P50.MethodsNine humans with a HAH mutation (6 female, Age: 40±12yrs, P50: 16±1 mmHg) and 12 controls with typical affinity hemoglobin (6 female, Age: 40±10yrs, P50: 26±1 mmHg) laid supine for 10‐minutes prior to 20‐minutes of isocapnic hypoxia, titrated to reduce arterial O2 pressure to ~50 mmHg (Avg. FiO2 = 11.9±0.0%). Beat‐to‐beat arterial pressures (arterial catheter) and heart rate (electrocardiogram) were continuously recorded. Data were averaged in five‐minute segments starting with the last five minutes of supine normoxic rest. Spontaneous cBRS was quantified using the sequence method. HRV was measured in time and frequency domains. Standard deviation of the RR interval (SDRR) was calculated as the standard deviation of all RR intervals in a data segment. Low frequency (LF) HRV was calculated using Fast Fourier Transformation and assessed as absolute spectral intensity in the LF band (0.04‐0.15Hz).ResultsArterial oxygen (PaO2) and carbon dioxide (PaCO2) pressures were not different between humans with HAH and controls during normoxia or isocapnic hypoxia [PaO2: (HAH vs. Control): 48±3 vs. 47±2 mmHg, p=0.612; PaCO2: (HAH vs. Control): 40±3 vs. 39±1 mmHg, p=0.328] exposure. cBRS was lower in humans with HAH compared to controls in normoxia and throughout isocapnic hypoxia [normoxia (HAH vs. Control): 7±4 vs. 16±10 ms/mmHg; hypoxia minutes 15‐20 (HAH vs. Control): 4±3 vs. 14±11 ms/mmHg; Hb type, p=0.024]. Several metrics of HRV were lower in humans with HAH relative to control (SDRR: Hb type, p≤0.001; LF: Hb type, p=0.030) and HRV was blunted to a similar extent in both groups with hypoxia (SDRR: time effect, p=0.009).ConclusionThe findings of this study are twofold. Compared to controls, humans with HAH have: 1) attenuated cardiac baroreflex sensitivity and 2) lower heart rate variability in both normoxia and isocapnic hypoxia.

Cardiac autonomic modulation in children with severe liver disease, before and after liver transplantation.

The cardiovascular system is directly influenced by the autonomic nervous system (ANS); its changes affect heart rate variability (HRV) and are sensitive indicators of physiological changes. Autonomic dysfunction (AD) is manifested in up to 60% of patients with cirrhosis. Therefore, we aim to analyze the indexes of HRV pre- and post-surgery of children submitted for liver transplantation (LT). HRV, in children of both genders from 6 months of age to 10 years, that attended at the pediatric surgery clinic in the queue for LT at the Children's Institute were analyzed. To access HRV we analyzed indexes such as standard deviation of the RR intervals (SDNN), root-mean-square of the successive normal sinus RR interval difference (RMSSD), low frequency (LF), high frequency (HF), and LF/HF. The analysis of the behavior of cardiac autonomic modulation, in the period prior to LT and after surgery, showed an increase in HRV linear parameters SDNN, TINN (triangular interpolation of NN interval histogram), HFms2. In the time domain, there was also an increase in the HFms2 index. The analysis of the period preceding LT and two months after surgery showed an increase in the HRV linear parameters representing a global HRV improvement. In the time domain, there was also an increase in the HFms2 index, parasympathetic tone of the HRV.

Evaluating mental workload during multitasking in simulated flight.

BackgroundPilots must process multiple streams of information simultaneously. Mental workload is one of the main issues in man–machine interactive mode when dealing with multiple tasks. This study aimed to combine functional near‐infrared spectroscopy (fNIRS) and electrocardiogram (ECG) to detect changes in mental workload during multitasking in a simulated flight.MethodsTwenty‐six participants performed three multitasking tasks at different mental workload levels. These mental workload levels were set by varying the number of subtasks. fNIRS and ECG signals were recorded during tasks. Participants filled in the national aeronautics and space administration task load index (NASA‐TLX) scale after each task. The effects of mental workload on scores of NASA‐TLX, performance of tasks, heart rate (HR), heart rate variability (HRV), and the prefrontal cortex (PFC) activation were analyzed.ResultsCompared to multitasking in lower mental workload conditions, participants exhibited higher scores of NASA‐TLX, HR, and PFC activation when multitasking in high mental workload conditions. Their performance was worse during the high mental workload multitasking condition, as evidenced by the higher average tracking distance, smaller number of response times, and longer response time of the meter. The standard deviation of the RR intervals (SDNN) was negatively correlated with subjective mental workload in the low task load condition and PFC activation was positively correlated with HR and subjective mental workload in the medium task load condition.ConclusionHR and PFC activation can be used to detect changes in mental workload during simulated flight multitasking tasks.

Cardiovascular Autonomic Function Tests in Patients of Obsessive-Compulsive Disorder: A Cross-Sectional Study.

Background:Patients with psychiatric disorders are at an increased risk of developing cardiovascular disease, reducing life expectancy. Autonomic dysfunction has been linked to this increased risk; many studies have found reductions in heart rate variability (HRV). Only a few studies have systematically explored the relationship between obsessive–compulsive disorder (OCD) and autonomic function, and they have found contradicting results. The present study is intended to explore comprehensive autonomic functions in OCD patients and compare them with healthy controls.Methods:A total of 18 OCD patients meeting Diagnostic and Statistical Manual of Mental Disorders - 5 (DSM-5) criteria were enrolled to undergo comprehensive autonomic function testing, and the results were compared with 25 age- and sex-matched healthy controls.Results:Time-domain parameters of HRV such as standard deviation of the RR intervals, coefficient of variance of RR intervals, standard deviation of differences between adjacent RR intervals, root square of the mean of the sum of the squares of differences between adjacent RR intervals, and percentage of number of RR interval differences ≥ 50 ms were significantly lower in OCD patients, indicating lesser parasympathetic tone. Frequency-domain parameters such as total power and very low frequency were significantly lower in OCD patients, indicating a significant decrease in autonomic tone. Nonlinear parameters such as dispersion of points perpendicular to the line of identity and dispersion of points along the line of identity were significantly lower in OCD patients, indicating altered vagal and sympathetic tone. In autonomic reactivity tests, the fall in systolic blood pressure during the lying to standing test and change in diastolic blood pressure during the cold pressor test were significantly altered in OCD patients, indicating abnormal sympathetic reactivity. There was no significant correlation between autonomic parameters and the severity of OCD.Conclusion:OCD is characterized by a decreased parasympathetic tone and abnormal sympathetic reactivity compared to normal controls.

Heart Rate Variability during Wake and Sleep in Huntington’s Disease Patients: An Observational, Cross-Sectional, Cohort Study

Introduction: Autonomic dysfunction has been reported as one of nonmotor manifestations of both presymptomatic and manifest Huntington’s disease (HD). The aim of our study was to evaluate heart rate variability (HRV) during wake and sleep in a cohort of patients with manifest HD. Methods: Thirty consecutive patients with manifest HD were enrolled, 14 men and 16 women, mean age 57.3 ± 12.2 years. All patients underwent full-night attended video polysomnography. HRV was analyzed during wake, NREM sleep, and REM sleep, in time and frequency domain. Results were compared with a control group of healthy volunteers matched for age and sex. Results: During wake, HD patients presented significantly higher mean heart rate than controls (72.4 ± 9.6 vs. 58.1 ± 7.3 bpm; p < 0.001). During NREM sleep, HD patients showed higher mean heart rate (65.6 ± 11.1 vs. 48.8 ± 4.6 bpm; p < 0.001) and greater low frequency (LF) component of HRV (52.9 ± 22.6 vs. 35.5 ± 17.3 n.u.; p = 0.004). During REM sleep, we observed lower standard deviation of the RR interval in HD subjects (3.4 ± 2.2 vs. 3.7 ± 1.3 ms; p = 0.015). Conclusion: Our results show that HD patients have higher heart rate than controls, during wake and NREM, but not during REM sleep. Among HRV parameters, the most relevant difference regarded the LF component, which reflects, at least partially, the ortho-sympathetic output. Our results confirm the involvement of autonomic nervous system in HD and demonstrate that it is evident during both wake and sleep.

Cardiovascular risk associated with long-term anabolic-androgenic steroid abuse: an observational study from Norway

Abstract Background The use of anabolic-androgenic steroids (AAS) has become highly prevalent among recreational weightlifters. Numerous case reports have suggested an association between AAS use and a vast range of different cardiovascular diseases, including sudden cardiac death (SCD) and coronary artery disease (CAD). Few clinical studies have evaluated the risk of SCD and the prevalence of CAD in individuals with long-term AAS use. Purpose To evaluate the risk of ventricular arrhythmias and the prevalence of CAD among men with long-term AAS use. Methods Strength-trained men with at least three years of cumulative AAS use were recruited from recreational gyms. The control group consisted of strength-trained competing athletes who self-reported never using any performance enhancing drugs (non-users). AAS use was verified by sophisticated blood and urine analyses. Study participants went through a comprehensive cardiovascular evaluation including exercise ECG, 24 h ECG, heart rate variability (HRV) measures, signal averaged ECG (SAECG) and QT dispersion (QTd). Coronary computed tomography angiography (CCTA) was performed in AAS users. Not all participants had all tests. Results We included 51 AAS users and 21 non-users. Median age (25th-75th percentile) was 33 (29–37) years in the user group and 33 (29–42) years in the non-user group. Forty-eight (94%) of the users had been using AAS for five years or more. Characteristics are presented in the table. AAS users had significantly lower HDL values compared to non-users (p&amp;lt;0.001). No signs of ischemia or arrhythmias were detected during exercise ECG, however maximal exercise capacity was lower than in the control group and also compared to age-standardized values. A considerable, but statistically non-significant reduction was seen in overall HRV estimated as the standard deviation of the RR intervals for normal sinus beats (SDNN) (p=0.05). No difference was seen regarding left ventricular late potentials or QTd (table). Eight (19%) of the forty-two AAS users undergoing CCTA had at least a mild degree of CAD, and four of them three-vessel disease. Conclusion No ECG-findings indicated an increased risk of ventricular arrhythmias among the long-term AAS users. However, their maximal exercise capacity was lower than in controls, and one fifth of the long-term AAS users had verified CAD on CT coronary angiography. Funding Acknowledgement Type of funding sources: None. Table 1

Alteration of Autonomic Nervous System Is Associated With Severity and Outcomes in Patients With COVID-19.

BackgroundPrevious studies suggest that coronavirus disease 2019 (COVID-19) is a systemic infection involving multiple systems, and may cause autonomic dysfunction.ObjectiveTo assess autonomic function and relate the findings to the severity and outcomes in COVID-19 patients.MethodsWe included consecutive patients with COVID-19 admitted to the 21st COVID-19 Department of the east campus of Renmin Hospital of Wuhan University from February 6 to March 7, 2020. Clinical data were collected. Heart rate variability (HRV), N-terminal pro-B-type natriuretic peptide (NT-proBNP), D-dimer, and lymphocytes and subsets counts were analysed at two time points: nucleic-acid test positive and negative. Psychological symptoms were assessed after discharge.ResultsAll patients were divided into a mild group (13) and a severe group (21). The latter was further divided into two categories according to the trend of HRV. Severe patients had a significantly lower standard deviation of the RR intervals (SDNN) (P < 0.001), standard deviation of the averages of NN intervals (SDANN) (P < 0.001), and a higher ratio of low- to high-frequency power (LF/HF) (P = 0.016). Linear correlations were shown among SDNN, SDANN, LF/HF, and laboratory indices (P < 0.05). Immune function, D-dimer, and NT-proBNP showed a consistent trend with HRV in severe patients (P < 0.05), and severe patients without improved HRV parameters needed a longer time to clear the virus and recover (P < 0.05).ConclusionHRV was associated with the severity of COVID-19. The changing trend of HRV was related to the prognosis, indicating that HRV measurements can be used as a non-invasive predictor for clinical outcome.