Standard Deviation Of NN Intervals Research Articles

Measurement of Trauma Caregiver Stress: Validation of Heart rate variability in a Real-World Surgical Setting

BackgroundAcute stress is a potentially modifiable risk-factor that contributes to errors in trauma care. Research on stress mitigation is limited by the lack of a validated objective measure of surgeon stress. We sought to validate HRV in a real-world surgical setting by comparison to the Subjective Units of Distress Score (SUDS), and correlation with self-reported peak stress moments. MethodsAttending and resident surgeons on the trauma team at a Level I Trauma Center wore armbands to measure HRV. Stress-associated blunting of HRV was analyzed using the standard deviation of N-N intervals (SDNN) and the root mean square of successive differences . Perceived stress was measured with the SUDS at random intervals and at perceived stress peaks. SUDS and HRV metrics were compared with a mixed effect regression model. Correlation between binned SUDS quartiles and HRV was evaluated. HRV at reported peak-stress moments were compared to shift baseline values. ResultsTwelve participants were monitored for 340 h, producing 135 SUDS responses and 65 peak-stress time points. Regression analysis demonstrated no correlation between HRV and SUDS. With a binned approach, decreased SDNN was associated with an elevated SUDS (P = 0.03). The self-identified peak-stress moments correlated with decreases in both SDNN and root mean square of successive differences (P = 0.02; P < 0.01). ConclusionsHRV by SDNN analysis correlated with heightened perceived stress, supporting its validity as a measure. However, the wide, frequent variation of HRV tracings within subjects, the sensitivity of HRV to of analytic technique, and the impact of confounders may limit its utility as an education or research tool. Level of EvidenceV Diagnostic test.

89 Learning ability and physiological stress response of horses (Equus caballus) undergoing discrimination and reversal learning tasks using a touch screen

The objective of this study was to evaluate the cognitive abilities and physiological stress responses of horses ( Equus caballus ) undergoing discrimination and reversal learning tasks using a touch screen powered by a computer. Utilizing such technology to present stimuli and collect data points provided standardization across all test subjects, and removed human error and bias from the experimentation. The study population consisted of 9 horses and ponies, all managed similarly at the same facility. The horses, 5 mares and 4 geldings, were aged 10–23 years (mean 14.8, ± 3.03). These 9 subjects were tested on discrimination learning based on their ability to select a pre-determined 2-dimensional shape (black circle or triangle) and their performance measured as a percentage of correct responses within a given session. Latency to touch the screen was also recorded, in seconds. Once this task was acquired, as determined by completing 2 consecutive sessions at ≥ 80% performance, the horses were then tested on reversal learning by switching the previously-rewarded shape to the unrewarded one, and the previously-unrewarded shape to the rewarded one. Before any experimentation began, horses were habituated to the experimental environment and shaped to touch the screen with their muzzles. Positive reward in the form of food was the only reinforcement method used throughout the study. The following physiological stress variables were recorded during all sessions by Polar H10 Heart Rate Sensors: standard deviation of NN intervals (SDNN), root mean square of successive rr-interval differences (RMSSD), and the ratio of low frequency to high frequency (LF/HF). Statistical analysis was performed using Spearman rank correlation coefficients to assess the potential relationships between performance, latency, and any of the stress variables. Results showed that performance and latency were positively correlated in both discrimination and reversal learning ( P < 0.001, Spearman's rho = 0.358, α = 0.05 and P < 0.001, and Spearman's rho = 0.512, α = 0.05, respectively). No significant correlation was found between either performance or latency and SDNN, RMSSD, or LF/HF. These results suggest that making comparatively slow, deliberate choices were linked to a higher performance.

Effect of moderate intensity aerobic training on cardiac autonomic system function and nitric oxide levels in middle-aged males with metabolic syndrome

Background and Aims: The sedentary lifestyle in individuals with metabolic syndrome is a main threatening risk for their health. This study aimed to investigate the effects of aerobic exercise with 65% of maximal oxygen consumption on heart rate variability and vascular nitric oxide levels in middle-aged males with metabolic syndrome. Materials and Methods: In total, 30 middle-aged men with metabolic syndrome were randomly divided into control and aerobic training groups. At the pretest and posttest, the values ​​of metabolic risk indices, heart rate variability, and nitric oxide were measured in both groups. The aerobic training group performed aerobic exercise for eight weeks at 65% of maximal oxygen consumption. The data were analyzed using the independent and paired t-tests. Results: According to the results, after comparing the values obtained from the posttest and pretest, there was a significant difference between the training and control groups regarding the fasting blood glucose, triglyceride, metabolic Z score, Standard deviation of NN intervals (SDNN), Square root of the mean squared differences of successive NN intervals (rMSSD), very-low-frequency (VLF), High frequency (HF), and vascular nitric oxide levels. Total cholesterol and low-density lipoprotein levels were significantly different in the aerobic training group, compared to those of the control group and LF as well as LF/HF at the pretest (P=0.01). However, despite slight changes in high lipoprotein and blood pressure levels, there was no significant difference in the aerobic training group, compared to the control group and pre-test. Conclusion: Regular moderate-intensity aerobic exercise can be used as an appropriate exercise protocol to improve cardiovascular function for males with metabolic syndrome.

Characterization of cardiac autonomic function in COVID-19 using heart rate variability: a hospital based preliminary observational study.

The novel corona virus disease, which was initially reported in China in late 2019, has become a global pandemic affecting 330 million cases. COVID-19 affects predominantly the respiratory system, in addition to other organ systems, mainly the cardiovascular system. One of the hypotheses is that virus entering the target cells by binding to angiotensin converting enzyme 2 affecting hypothalamic pituitary axis could lead to dysautonomia which is measured by heart rate variability (HRV). HRV is a non-invasive measure of autonomic function that facilitates identification of COVID-19 patients at the risk of developing cardiovascular complications. So, we aimed to assess HRV in COVID patients and compare between COVID patients and normal controls. In a case control design, we compared 63 COVID-19 infected patients with 43 healthy controls matched for age and gender. Along with clinical characterization, heart rate variability was evaluated using ambulatory 5min ECG in lead II and expressed in frequency and time domain measures. Statistical analysis was performed using SPSS 17.0. Mean age of the study population was 49.1±14.2years and 71 (66.9%) were males. Frequency domain measures high (HF) and low (LF) frequency powers were significantly decreased in COVID-19 patients compared to controls. HF/LF and LF/HF ratios were not different between groups. Time domain measures rMSSD (root mean square of successive RR interval differences) and SDNN (standard deviation of NN intervals) were significantly increased among COVID-19 subjects. COVID-19 infection was associated with increased parasympathetic activity as defined by rMSSD>40 {adjusted odds ratio 7.609 (95% CI 1.61-35.94); p=0.01} and SDNN>60 {adjusted odds ratio 2.620 (95% CI 1.070-6.44); p=0.035} after adjusting for age, gender and comorbidities. Our study results showed increased parasympathetic tone in COVID patients. Early diagnosis of autonomic imbalance in COVID patients is needed to plan management and limit progression of disease.

Phasic heart rate variability and the association with cognitive performance: A cross-sectional study in a healthy population setting.

IntroductionSympathovagal balance measured by heart rate variability is a core component of psychophysiological research. Through the close link of physiological and psychological aspects, often a reduced heart rate variability is associated with impaired cognitive function. A better understanding of the associations between cognitive and cardiovascular dysfunctions is necessary to prevent the manifestation of diseases. Therefore, this study investigated phasic heart rate variability using rest, anticipatory, stress, and recovery periods and the association with high and low cognitive performance in a generally healthy population setting.Methods114 healthy individuals (40 males, 74 females) aged 20 to 70 participated in the cross-sectional study. The heart rate variability based on standard deviation of NN intervals (SDNN), and the root means square of successive differences (RMSSD), low frequency (LF), high frequency (HF) and LF/HF ratio and its association with high and low cognitive performance measured by the California Verbal Learning Task II were examined.ResultsThe results of this study indicate that the paradigm was successful in producing stress and showed a significant association between phasic heart rate variability (SDNN) and verbal episodic memory performance, irrespective of age and sex.DiscussionThe results of this study suggest that a reduced heart rate variability is associated with reduced cognitive function regardless of age and sex and seem to be an early indicator of sympathovagal disbalance.ConclusionThis leads to the conclusion that differences between high and low cognitive performance might show differences in heart rate variability at an early stage, where no diseases are yet manifest.

Integrating Breathing Techniques Into Psychotherapy to Improve HRV: Which Approach Is Best?

IntroductionApproaches to improve heart rate variability and reduce stress such as breathing retraining are more frequently being integrated into psychotherapy but little research on their effectiveness has been done to date. Specifically, no studies to date have directly compared using a breathing pacer at 6 breaths per minute with compassion focused soothing rhythm breathing.Current StudyIn this randomized controlled experiment, 6 breaths per minute breathing using a pacer was compared with compassion focused soothing rhythm breathing, with a nature video being used as a control group condition.MethodsHeart rate variability (HRV) measures were assessed via electrocardiogram (ECG) and respiration belt, and an automated blood pressure machine was used to measure systolic diastolic blood pressure, and heart rate (HR). A total of 96 participants were randomized into the three conditions. Following a 5-min baseline, participants engaged in either 6 breath per minute breathing, soothing rhythm breathing, or watched a nature video for 10 min. To induce a stressful state, participants then wrote for 5 min about a time they felt intensely self-critical. Participants then wrote for 5 min about a time they felt self-compassionate, and the experiment ended with a 10-min recovery period.ResultsConditions did not significantly differ at baseline. Overall, HRV, as measured by standard deviation of NN intervals (SDNN), low frequency HRV (LF HRV), and LF/HF ratio, increased during the intervention period, decreased during self-critical writing, and then returned to baseline levels during the recovery period. High frequency HRV (HF HRV) was not impacted by any of the interventions. The participants in the 6 breath per minute pacer condition were unable to consistently breathe at that rate and averaged about 12 breaths per minute. Time by Condition analyses revealed that both the 6 breaths per minute pacer and soothing breathing rhythm conditions lead to significantly higher SDNN than the nature video condition during breathing practice but there were no significant differences between conditions in response to the self-critical and self-compassionate writing or recovery periods. The 6 breath per minute pacer condition demonstrated a higher LF HRV and LF/HF ratio than the soothing rhythm breathing condition, and both intervention conditions had a higher LF HRV and LF/HF ratio than the nature video.ConclusionsAlthough the 6 breath per minute pacer condition participants were not able to breath consistently at the low pace, both the participants attempting to breathe at 6 breaths per minute as well as those in the soothing rhythm breathing condition effectively increased HR variability as measured by SDNN, and attempting to breathe at 6 breaths per minute led to the highest LF HRV and LF/HF ratio. Both breathing approaches impacted HRV more than watching a relaxing nature video and can potentially be used as key adjuncts in psychotherapy to aid in regulating physiological functioning, although it appears that consistent breathing practice would be needed.

Fast breathing facilitates reaction time and movement time of a memory-guided force pulse

Slow controlled breathing can be beneficial for performance of continuous and serial motor tasks. However, how controlled breathing influences discrete motor task performance remains unclear. We sought to determine the impact of paced breathing frequency on measures of movement initiation (reaction time: RT), accuracy (absolute endpoint error: AE; constant error: CE), and variability (trial-to-trial variability: V), in a goal-directed discrete motor task. We hypothesized slow breathing would be accompanied by faster RT, reduced AE and CE, and less V compared to faster breathing rates. Participants (N=47) performed a memory-guided force pulse pinch task targeted at 10% of their maximum voluntary contraction while breathing at metronome-paced slow, normal, and fast frequencies. During each breathing condition, heart rate variability (HRV) as indexed by the standard deviation of 'NN' intervals (SDNN) was measured to ensure objective manipulation check of participants breathing at their set pace. Following each breathing condition, participants provided subjective ratings using the Affect Grid and Visual Analog Scales for arousal, hindrance, and dyspnea. Manipulation check results indicated participants correctly breathed at metronome paces, as indexed by increased HRV for slow breathing and decreased HRV for fast breathing. Results indicated that fast breathing reduced reaction time and movement time, and increased ratings of arousal, hindrance, and dyspnea. In contrast, slow breathing increased reaction time, and levels of hindrance and dyspnea were similar to normal breathing. Breathing frequency did not differentially impact accuracy or variability across conditions. Findings provide evidence that breathing frequency affects fundamental movement parameters, potentially mediated by factors other than arousal.

Experimental Study of Thermal Comfort Based on Driver Physiological Signals in Cooling Mode under Summer Conditions

In this study, electroencephalogram (EEG), photo-plethysmography (PPG), and surface temperature measurements of subjects were taken while performing a driving simulation when the cabin and vent discharge air temperature in summer were changed from discomfort to comfort conditions. Additionally, subjective questionnaires were used to analyze the subject’s thermal comfort under the various driving environments. As a result, the surface temperatures of the forehead, left hand, right hand, and abdomen of the subject during driving were reduced by 2, 0.97, 2.18, and 5.86 °C, respectively, by operating a 12.5 °C vent cooling function at a cabin temperature of 35 °C. As a comprehensive analysis of the subjective survey, PPG, and EEG results, total power (TP), the standard deviation of N-N interval (SDNN), and the root mean square of successive differences (RMSSD) of subjects increased and stress index decreased at cabin and vent discharge air temperatures of 30–27.5 °C and 16.5–18.5 °C, respectively. Furthermore, the relative sensory motor rhythm (SMR) wave and concentration index (CI) of the frontal lobe tended to increase under the same temperature conditions. Accordingly, it was confirmed that these temperature conditions provided a pleasant driving environment for the driver and increased concentration on driving.

Autonomic nervous system abnormalities predict cardiovascular changes after initiation of siponimod in secondary progressive multiple sclerosis

ObjectiveThe aim of this study was to identify whether autonomic nervous system (ANS) dysfunction identified prior to treatment initiation can predict siponimod related decrease in heart rate (HR) after treatment initiation. MethodsIn 26 people with secondary progressive multiple sclerosis (SPMS) the following ANS testing protocol was applied: 10-min supine resting position, Valsalva maneuver, deep breathing test, 10 min tilt-up table test, 5-min supine resting period, ingestion of siponimod, followed by 180-min supine resting period recordings. Heart rate variability (HRV) parameters were investigated as possible predictors of decrease in HR (ΔHR) after treatment initiation. ResultsAfter treatment initiation, there was a statistically significant drop in HR (71.1 ± 9.2 to 66.3 ± 8.1, p < 0.001) and elevation of systolic blood pressure (sBP) (113.2 ± 12.4 to 117.1 ± 10.8, p = 0.04). Values of the diastolic BP (dBP) followed similar trend as did sBP, however not reaching statistical significance (72.8 ± 9.6 to 74.9 ± 8.3, p = 0.13). In a multivariable regression model, disease duration and standard deviation of NN intervals (SDNN) were identified as independent predictors for ΔHR, where increase in SDNN and longer disease duration predict smaller ΔHR. ConclusionANS abnormalities may predict cardiovascular abnormalities associated with treatment initiation with siponimod. SignificanceResults of this study may help mitigate risks associated with siponimod treatment.

Long-Term Influence of Concussion on Cardio-Autonomic Function in Adolescent Hockey Players.

Concussion may negatively influence cardiovascular function and the autonomic nervous system, defined by alteration in heart rate variability (HRV). Differences in HRV most commonly emerge during a physical challenge, such as the final steps of the return-to-sport progression. To assess the effect of concussion history on aspects of cardio-autonomic function during recovery from a bout of submaximal exercise in adolescent male hockey athletes. Case-control study. Research laboratory. Thirty-three male athletes participating in Midget-AAA hockey were divided into those with (n = 15; age = 16 ± 1 years, height = 1.78 ± 0.06 m, mass = 73.9 ± 7.4 kg, 10.5 ± 1.6 years of sport experience, 25.2 ± 18.3 months since last injury) or without (n = 18; age = 16 ± 1 years, height = 1.78 ± 0.05 m, mass = 74.8 ± 7.6 kg, 10.6 ± 1.9 years of sport experience) a concussion history. Those with a concussion history were binned on total count: 1 concussion or 2 or more concussions. All athletes underwent 5 minutes of resting HRV assessment, followed by 20 minutes of aerobic exercise at 60% to 70% of their maximal target heart rate and a 9-minute, postexercise HRV assessment. Heart rate variability measures of mean NN interval, root mean square of successive differences, and standard deviation of NN interval (SDNN). Group demographic characteristics were not different. When the control and concussed groups were compared, group and time main effects for heart rate recovery, root mean square of successive differences, and SDNN (P values < .01), and an interaction effect for SDNN (P < .05) were demonstrated. Recovery trends for each group indicated that a history of 2 or more concussions may negatively affect cardio-autonomic recovery postexercise. Our findings suggest that those with more than 1 previous concussion may be associated with a greater risk for long-term dysautonomia. Future use of HRV may provide clinicians with objective guidelines for concussion-management and safe return-to-participation protocols.

Majmaah Bölgesi'nde (Suudi Arabistan Krallığı) Kardiyovasküler Hastalığı Olan Hastalarda Kardiyak Otonom Fonksiyon ile Metabolik Sendrom Arasındaki İlişki: Vaka Kontrol Gözlem Çalışması

Objective: Lacunae in literature persist regarding the mechanisms connected with the progression from metabolic syndrome (MetS) to Type 2 diabetes and cardiovascular disease (CVD). To validate heart rate variability (HRV), as a tool for progression of CVD in patients visiting cardiovascular outpatient clinic. Material and Methods: This crosssectional study involved screening of 126 patients for the presence of one or more cardiometabolic risk factors and followed with HRV measurement after categorizing them as MetS+ or control MetS-. Results: Time domain analysis showed a significant reduction between male and female of MetS- and MetS+ While frequency domain analysis in MetS+ male showed no difference, MetS+ female showed significant difference in TP and HF indices. With increasing number of metabolic components, the MetS+ males exhibited significant decrease in the time domain and increase in frequency domain indices of HRV. Body mass index (BMI), waist circumference (WC), high-density lipoprotein (HDL), and triglyceride (TG) were associated with time and frequency domain of HRV among MetS+ and MetS- males and females. Low density lipoprotein (LDL) was a significant predictor of SDNN, RRSSD, and NN50 in patients with MetS+ while HDL was a significant predictor of Standard deviation of normal-to-normal intervals (SDNN) and pNN50. BMI was significant predictor of SDNN and pNN50 in MetS- patients and NN50 in MetS+ patients. In MetS+, the significant predictor of HF was WC, TG, HDL and LDL and that of LF were TG and LDL while in MetS-, WC was significant predictor of LF and HDL of LF/HF. Conclusion: MetS+ females showed lower vagal activity and decreased sympathetic predominance as compared to MetS males suggesting greater cardiovascular risk.

Sympatho-vagal activity in the mothers of pediatric cancer and non-cancer patients

Aim: Pediatric diseases affect both the children and their families psychologically. Parents may experience stress with the development of these diseases. The autonomic nervous system is one of the systems activated in response to stress. The current study aimed to investigate the activity of sympatho-vagal axis in mothers of children with pediatric diseases. Materials and Methods: Following ethical consent, the study was carried out on the mothers of healthy children (healthy, n=25) and children with cancer (cancer, n=25), and children with non-cancer disease (non-cancer, n=25). Heart rate variability was used to assess autonomic nervous system’s activity by taking a 5 min electrocardiogram recording. Heart rate variability (HRV) parameters such as standard deviation of RR intervals, mean square of successive RR interval differences, and low frequency/high frequency band were calculated by special software. Results: Standard deviation of NN intervals (healthy 37±2, non-cancer 35±2, cancer 35±3), root mean square of successive RR interval differences (healthy 33±3, non-cancer 30±3, cancer36±5), LF/HF (healthy 1.69±0.21, non-cancer 1.40±0.17, cancer 1.30±0.16) and other HRV findings (p>0.05) were not different among the mothers. Systolic blood pressures were higher (p=0.000) in the mothers of healthy children (115±2) than in mothers of children with non-cancer diseases (102±2) and with cancer (109±2). Diastolic blood pressures were higher (p=0.022) in mothers of healthy children (79±2) compared to mothers of children with non-cancer disease (73±1), but not from those mothers of children with cancer (78±2). Conclusion: Mothers did not differ in terms of HRV parameters, suggesting that children, whether healthy or sick, are always perceived as a great responsibility by the mothers.

Pre-Emption of Affliction Severity Using HRV Measurements from a Smart Wearable; Case-Study on SARS-Cov-2 Symptoms.

Smart wristbands and watches have become an important accessory to fitness, but their application to healthcare is still in a fledgling state. Their long-term wear facilitates extensive data collection and evolving sensitivity of smart wristbands allows them to read various body vitals. In this paper, we hypothesized the use of heart rate variability (HRV) measurements to drive an algorithm that can pre-empt the onset or worsening of an affliction. Due to its significance during the time of the study, SARS-Cov-2 was taken as the case study, and a hidden Markov model (HMM) was trained over its observed symptoms. The data used for the analysis was the outcome of a study hosted by Welltory. It involved the collection of SAR-Cov-2 symptoms and reading of body vitals using Apple Watch, Fitbit, and Garmin smart bands. The internal states of the HMM were made up of the absence and presence of a consistent decline in standard deviation of NN intervals (SSDN), the root mean square of the successive differences (rMSSD) in R-R intervals, and low frequency (LF), high frequency (HF), and very low frequency (VLF) components of the HRV measurements. The emission probabilities of the trained HMM instance confirmed that the onset or worsening of the symptoms had a higher probability if the HRV components displayed a consistent decline state. The results were further confirmed through the generation of probable hidden states sequences using the Viterbi algorithm. The ability to pre-empt the exigent state of an affliction would not only lower the chances of complications and mortality but may also help in curbing its spread through intelligence-backed decisions.

Supplementation of Kaempferia parviflora Extract Enhances Physical Fitness and Modulates Parameters of Heart Rate Variability in Adolescent Student-Athletes: A Randomized, Double-Blind, Placebo-Controlled Clinical Study

This randomized double-blind controlled study aimed to investigate the effects of a standardized Kaempferia parviflora (KP) extract on the physical fitness and heart rate variability (HRV) parameters in adolescent sport school students. 194 male students were recruited and randomized into two groups (n = 97), matched by age and sports. The KP-treated group received KP extract capsules at a dose of 360 mg/day and the control group received placebo capsules, continuously for 12 weeks. Physical fitness performance and HRV parameters were monitored with blood biochemical analysis for product safety. KP extract significantly increased the right-hand grip strength, the back-leg strength and maximal oxygen consumption (VO2 max) and decreased the time used for 50-meter sprint test without changing the sit-and-reach test and the 40 yard technical test. For HRV parameters, KP extract significantly increased standard deviation of normal to normal intervals (SDNN), square root of the mean of square of successive normal to normal interval differences (RMSSD) and high frequency (HF) norm, without changing low frequency (LF) norm and LF/HF ratio. The increase in stress resistance and decrease in stress index were found in the KP-treated group, without changing the autonomic nervous system (ANS) activity and balance. Blood biochemical analysis showed normal values of all participants. This data indicates the safety and positive effects of KP on muscle strength, endurance and speed, but not on the flexibility and agility. The modulatory effects of KP extract on HRV parameters suggest its anti-stress effects and would encourage the application in a sport training and exercise.

Abstract 15203: Acute Electronic Cigarette Exposure Decreases Heart Rate Variability in C57BL/6 Mice

Background: Despite a lack of empirical data, an unprecedented rise in electronic cigarettes (ECs) has been widely perceived as safe. Multiple studies support a causal link between tobacco cigarette (TC) use and a decline in cardiovascular (CV) health; however, there is a paucity of data with EC use. A study showed EC use decreased HRV in humans via increased sympathetic activation- a known mechanism predictive of CV disease from TC use. We aimed to develop a mouse model to determine if acute EC exposure modifies HRV in mice. Methods: Telemetry devices were implanted in the abdomen of 6 eight-week-old C57BL/6 mice to monitor ECG activity continuously. Mice underwent a 1-hr acclimation phase in exposure chambers followed by a 1-hour exposure to air (control). EC exposures consisted of two 15-min sessions (4-sec puff/26-sec air) to BluPlus® 2.4% nicotine (Classic Tobacco) with a 15-min period of aerosolized PBS added as a secondary control. For each exposure episode, a 45-min post-exposure event followed. Ponemah v6.20 software was used for HRV analysis of the time domain. A linear mixed-effects model with a robust estimator was used to determine the relationship between air vs. combined EC events and PBS (n = 1,109). R (Version R3.6.3) was utilized to test for statistical significance at α = 0.05. Results: EC exposures significantly decreased the standard deviation of NN intervals (SDNN) and root mean square of successive differences (RMSSD) by 5.00 and 9.34 units as compared to air exposures, suggesting reductions in total and short-term autonomic variability (Table 1). Both parameters increased in the post-EC periods as compared with the EC exposures. Conversely, PBS vs. air exposure showed a marked increase in SDNN and RMSSD. Conclusion: Short-term exposures to ECs decreased HRV in mice, consistent with similar results in human studies, suggesting that ECs could increase cardiovascular risk in an acute manner.

Abstract 13369: Sympathovagal Imbalance Decades After Atrial Septal Defect Repair

Introduction: Heart rate variability (HRV), a measure of the autonomic nervous system activity, is a morbidity and mortality predictor. HRV is decreased in children with atrial septal defects (ASD) indicating parasympathetic withdrawal and sympathetic predominance, and increased right atrial end-diastolic pressure is believed to influence the sympathovagal balance. Despite the belief of a benign long-term outcome after closure, ASD patients have increased mortality rates after the age of 30 yrs. This may correlate to HRV, why we study HRV in adults after closure. Hypothesis: ASD patients have impaired HRV after closure when compared with controls. Methods: Surgically closed ASD patients (n=17, mean age 32±9 yrs., mean time since closure 19±8 yrs.), percutaneously closed ASD patients (n=18, mean age 28±7 yrs., mean time since closure 15±5 yrs.) and age- and gender-matched controls (n=15, mean age 30±9 yrs.) underwent a 48-hr Holter monitoring. Inclusion criteria were an age of minimum 2 yrs. at the time of diagnosis and minimum 3 yrs. must have passed since ASD closure. The following time-domain HRV measures were analyzed: SD of NN intervals (SDNN), SD of the average NN interval for each 5-minute segment, mean of the SDs of all NN intervals for each 5-minute (SDNNi), root mean square of successive RR interval differences (RMSSD), percentage of successive RR intervals that differ by &gt;50 ms (pNN50), and triangular index. Results: Surgically closed ASD patients have an impairment of all time-domain parameters, while transcatheter closed patients have an impairment of half the parameters. Conclusion: These novel findings demonstrate a cardiac sympathovagal imbalance in adult patients several yrs. after ASD closure and may potentially explain why we observe a long-term morbidity and mortality increase in ASD patients.

Impaired heart rate variability triangular index to identify clinically silent strokes in patients with atrial fibrillation

Abstract Introduction The identification of clinically silent strokes in patients with atrial fibrillation (AF) is of high clinical relevance as they have been linked to cognitive impairment. Overt strokes have been associated with disturbances of the autonomic nervous system. Purpose We therefore hypothesize that impaired heart rate variability (HRV) can identify AF patients with clinically silent strokes. Methods We enrolled 1358 patients with AF without a history of stroke or transient ischemic attack from the multicenter SWISS-AF cohort study who were in sinus rhythm (SR-group, n=816) or AF (AF-group, n=542) on a 5 minute resting ECG recording. HRV triangular index (HRVI), the standard deviation of normal-to-normal intervals (SDNN) and the mean heart rate (MHR) were calculated. Brain MRI was performed at baseline to assess the presence of large non-cortical or cortical infarcts, which were considered silent strokes without history of stroke or transient ischemic attack. We constructed binary logistic regression models to analyze the association between HRV parameters and silent strokes. Results At baseline, silent strokes were detected in 10.5% in the SR group and 19.9% in the AF group. In the SR-group, HRVI &amp;lt;15 was the only parameter independently associated with the presence of silent strokes (odds ratio (OR) 1.69; 95% confidence interval (CI): 1.04–2.72; p=0.033) after adjustment for various clinical covariates (age, sex, systolic blood pressure, history of hypertension, history of diabetes, history of heart failure, prior myocardial infarction, prior major bleeding, intake of oral anticoagulation, antiarrhythmics or betablockers). Similarly, in the AF-group, HRVI&amp;lt;15 was independently associated with the presence of silent strokes (OR 1.65, 95% CI: 1.05–2.57; p=0.028). SDNN&amp;lt;70ms and MHR&amp;lt;80 were not associated with silent strokes, neither in the SR group, nor in the AF group (Figure). Conclusions Reduced HRVI is independently associated with the presence of clinically silent strokes in an AF population, both when assessed during SR and during AF. Our data suggest that a short-term measurement of HRV in routine ECG recordings might contribute to identifying AF patients with clinically silent strokes. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Swiss National Science Foundation

Heart rate variability as a potential diagnostic tool to predict compensatory hyperhidrosis after sympathectomy in patients with primary focal hyperhidrosis.

BackgroundPrimary focal hyperhidrosis (PFH) is associated with autonomic nervous activity, and studies investigating this association in patients with PFH are very important. Heart rate variability (HRV) is a simple and noninvasive electrocardiographic test showing activity and balance in the autonomic nervous system, which consists of sympathetic and parasympathetic components. The aims of this study are to investigate associations between autonomic nervous activity and hyperhidrosis characteristics using HRV and to investigate the association between HRV findings and compensatory hyperhidrosis (CH) after sympathectomy.MethodsFrom March 2017 to March 2020, 105 subjects with PFH who underwent preoperative HRV tests and sympathectomy were analyzed. All subjects underwent bilateral thoracoscopic sympathectomy. T2 sympathectomy was conducted for craniofacial hyperhidrosis, and T3 sympathectomy was conducted for palmar hyperhidrosis. The following HRV parameters chosen to investigate the association between hyperhidrosis and autonomic nervous activity were measured by time and frequency domain spectral analysis: (I) time domain: standard deviation of normal-to-normal interval (SDNN) and square root of mean squared differences of successive normal-to-normal intervals (RMSSD), (II) frequency domain: total power (TP) of power spectral density, very low frequency (VLF), low frequency (LF), and high frequency (HF). HRV parameters were analyzed according to hyperhidrosis type (craniofacial vs. palmar type), sweat reduction, and CH after sympathectomy. In addition, the independent HRV parameters influencing CH after sympathectomy were investigated with multivariate analysis.ResultsCraniofacial hyperhidrosis was significantly more prevalent in the old age group (P<0.001). Sweat reduction after sympathectomy was significantly more prominent in palmar hyperhidrosis (P=0.037), and CH after sympathectomy was more prominent in craniofacial hyperhidrosis (P<0.001). Palmar type patients exhibited significantly larger SDNN, RMSSD, TP, LF, and HF than craniofacial type patients (all P<0.001). There were no significant differences in any HRV parameters according to sweat reduction after sympathectomy. Low-degree CH was associated with significantly larger SDNN, RMSSD, TP, LF, and HF than high-degree CH (P<0.001, P<0.001, P=0.002, P=0.001, and P<0.001, respectively). Multivariate analysis showed that HF and age group were associated with CH after sympathectomy (P=0.007 and P=0.010, respectively).ConclusionsThis study shows that HRV can provide useful insight into the pathophysiology of PFH and enhance preoperative risk stratification of CH. Large-scale, prospective studies are required to determine the predictive value of HRV in patients at risk for subsequent CH after sympathectomy.

Epigenetic mechanisms affecting heart rate variability

Background: Heart rate variability (HRV) is a reliable indicator of the many physiological factors affecting the heart. So our research aim was to investigate factors affecting HRV and their epigenetic mechanisms.Methods: We recruited 23 non-smoking female elders. Their HRVs were repeatedly measured using an automated HRV analyzer. Total RNA was isolated from blood samples collected every visits and used for epigenome-wide miRNA measurements. We evaluated relationships between miRNA levels and two HRV indicators, standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive differences (RMSSD). Results: Three miRNAs (miR-1255b-5p, miR-155-5p, and miR-411-5p) were positively associated with both SDNN and RMSSD. (p&lt;0.05 for relations with all 3 miRNAs). The predicted target genes of 3 miRNAs were found to be related with various disease classes including metabolic, cardiovascular and chemdependency. Furthermore, KEGG pathways on pathways in cancer (hsa05200), PI3K-Akt signaling pathway (hsa04151) and HTLV-I infection (hsa05166) in order of precedence were related with HRV. Conclusions: Our study results suggest a potential that HRV modifies epigenetic mechanisms, resulting in a variety of diseases.

QT interval abnormalities and heart rate variability in patients with cirrhosis

Background and study aimsWe aimed to assess the relationship of the QT interval and heart rate variability with the severity and aetiology of cirrhosis and determine the effect of propranolol on them. Patients and methodsThis prospective study included 44 patients with cirrhosis categorised into three groups based on the Child–Pugh score: groups 1, 2 and 3 (with 12, 15 and 15 patients, respectively). Demographic characteristics, propranolol administration, severity of cirrhosis evaluated by the Child–Pugh score, aetiology of cirrhosis, and serum sodium, potassium and calcium levels were evaluated. All patients underwent 24 h-Holter monitoring. Corrected QT interval (QTc), average heart rate, standard deviation of normal-to-normal intervals (SDNN) and corrected SDNN (cSDNN) were evaluated. ResultsThe average QTc was significantly longer in group 3 than in groups 1 and 2 (453.4 ± 17.4 vs 422.8 ± 18.6 and 428.9 ± 17.24 ms, p < 0.001). The median SDNN was 70 ms and was significantly lower in group 3 vs groups 1 and 2 (77; interquartile range [IQR], 67–89.5 vs 57; IQR, 38–68 and 75 ms; IQR, 61–81 ms, p = 0.003). cSDNN was significantly lower in group 3 vs groups 1 and 2 (200.0 ± 42.6 vs 254.5 ± 75.3 and 277.8 ± 110.6 ms, p = 0.022). Propranolol administration resulted in a significant increase in the average SDNN value but had no effect on cSDNN or QTc. QTc was associated with the Child–Pugh class (p < 0.001), viral aetiology (p = 0.009) and sex (p = 0.010); SDNN was associated with the mean heart rate (p = 0.015) and Child–Pugh class (p = 0.024). ConclusionQTc interval prolongation and decreased SDNN are common in cirrhosis. Their prevalence is closely associated with disease severity. Propranolol has no effects on cSDNN or QTc.