Adjacent RR Intervals Research Articles

Abstract 11419: Prognostic Value of Vagal Dysautonomia in Patients With Chagas Disease: 14-year Results of a Population Cohort of the Elderly

Introduction: The cardiac form is the main responsible for morbidity and mortality of Chagas disease (ChD), given its prevalence and unpredictable clinical evolution. A great part of ChD mortality occurs due to sudden ventricular arrhythmias, and the frequently observed autonomic dysfunction may be associated with unfavorable outcomes. We aimed to evaluate the predictive value of autonomic dysfunction indexes in ChD patients. Methods: The Bambuí Study of Aging is a prospective cohort of residents ≥60 years at study onset (1997), living in the southeastern Brazilian city of Bambuí (15,000 inhabitants). Consented participants underwent annual follow-up visits, and death certificates were tracked. For assessment of respiratory sinus arrhythmia (E:I ratio), patients were instructed to breathe deeply in a 10-second cycle (5 inhales and 5 exhales) while ECG was recorded. Heart rate variability indices (SDRR (standard deviation of adjacent RR intervals) and RMSSD (square root of the mean of the sum of squares of the differences between adjacent RR intervals)) were calculated using a computer algorithm, supervised by an independent cardiologist blinded to clinical data. Multivariable regression was performed to access the prognostic value of autonomic dysfunction indexes, expressed as tertiles, for all-cause mortality, after adjustment for demographic, clinical and ECG variables. Results: From 1,742 qualifying residents, 1,606 were enrolled, being 557 with positive ChD serology. Among these, mean age was 68 (64-74) years, and 32.5% were men. The most frequent ECG abnormality was right bundle branch block (23.2%). In 14 years, loss-to-follow-up was 7.9% and overall mortality was 51.9%. At total 321 ChD patients had valid autonomic indexes measurements. In univariate analyses, measurements of autonomic function predicted all-cause death: E:I ratio (HR: 1.20 (95% CI 1.09-1.33)), SDRR (HR: 1.26 (95% CI 1.14-1.40)) and RMSSD (HR: 1.12 (1.01-1.23)). After adjustment for sex, age and cardiovascular risk factors, none of these indexes remained as independent predictors of mortality. Conclusions: In a long-term cohort of elderly patients with ChD, abnormalities in autonomic function indexes were not independent predictors of 14-year mortality.

Does transcatheter ventricular septal defect closure affect heart rate variability in children?

BackgroundHeart rate variability (HRV) is a sign of the cardiac autonomic nervous system. Its evaluation in pediatric ventricular septal defect (VSD) cases before and after transcatheter closure contributes to an understanding of cardiac autonomic control. MethodsNineteen children with VSDs treated with transcatheter closure and 18 healthy children were enrolled in this study. A 24-h Holter rhythm monitor was applied to all patients before VSD closure and to those in the control group. Holter rhythm monitoring was repeated at three months in the patient group. HRV parameters were measured using the Cardio Scan Premier 12® program. Frequency-domain (total power; very-low-frequency, low-frequency (LF), and high-frequency (HF) indices; and the LF/HF ratio) and time-domain (standard deviation of all RR intervals (SDNN), standard deviation of 5-min averages of RR intervals (SDANN), the SDNN index, percentage of the difference between adjacent RR intervals, and the square root of the mean of the sum of square differences between adjacent filtered RR intervals) parameters were assessed. ResultsBefore the procedure, SDNN, SDANN, and total power values were lower in the patient group than in the control group; other parameters were similar in the two groups. No significant difference in the SDNN, SDANN, or total power was detected between the patient and control groups in the third month, indicating that autonomic control of patients’ hearts became normal during the third postoperative month. No correlation was detected between any hemodynamic parameters and any time-domain or frequency-domain parameters before closure. ConclusionThis study showed that transcatheter closure of VSDs changed HRV parameters in pediatric patients.

The Effects of Alpha-Glycerylphosphorylcholine on Heart Rate Variability and Hemodynamic Variables Following Sprint Interval Exercise in Overweight and Obese Women.

The current study examined the effects of Alpha-Glycerylphosphorylcholine (A-GPC) on heart rate variability (HRV) and hemodynamic responses following a sprint interval exercise (SIE) in women who were overweight or obese. Participants (n = 12, 31.0 ± 4.6 years; 29.4 ± 2.1 kg/m2) consumed 1000 mg of A-GPC or a placebo after eating breakfast in a randomized, double-blind cross-over design. After 60 min, participants performed two bouts of the SIE (30 s Wingate) interspersed with 4 min of active recovery (40 rpm). Hemodynamic variables and HRV domains were measured before and 60 min after the A-GPC consumption, immediately after SIE, and every 15 min up to 120 min during recovery. A-GPC consumption increased resting levels of both the time domain (Standard Deviation of RR wave intervals [SDNN] and percentage of interval differences of adjacent RR intervals greater than 50 ms [pNN50%]) and frequency domain (high frequency [HF] and low frequency [LF]) variables of HRV (p < 0.05). Moreover, HRV variables (except for LF/HF) decreased (p < 0.05) immediately after SIE in the A-GPC and placebo sessions. Systolic and diastolic blood pressure increased (p < 0.05) immediately after SIE in both trials. Both HRV and hemodynamic variables recovered (p < 0.05) faster in the A-GPC compared to the placebo session. We concluded that A-GPC consumption recovers HRV and blood pressure faster following strenuous exercise in overweight and obese women, and that it might favorably modify cardiac autonomic function.

Effect of SGLT-2 inhibitors on cardiac autonomic function in type 2 diabetes mellitus: a meta-analysis of randomized controlled trials.

Cardiac autonomic neuropathy (CAN) is a common complication of type 2 diabetes mellitus (T2DM). We sought to determine whether sodium-glucose co-transporter-2 (SGLT-2) inhibitors affect indices of CAN in patients with T2DM. We searched for parallel group or cross-over randomized controlled trials (RCTs) enrolling adult subjects with T2DM, assigned to a SGLT-2 inhibitor versus placebo or active comparator and addressing their effect on CAN. PubMed, Cochrane Library and gray literature sources were searched. We set as primary efficacy outcome the change in the low-frequency-to-high-frequency (LF/HF) ratio. We set as secondary efficacy outcomes: first, the change in the standard deviation of all 5min mean normal RR intervals and second, the change in the square root of the mean of the sum of the squares of differences between adjacent RR intervals (r-MSSD). Protocol has not been registered at a publicly available repository. We pooled data from four RCTs in a total of 247 subjects with T2DM. SGLT-2 inhibitor treatment did not have a significant effect on LF/HF ratio (MD = - 0.11, 95% CI - 0.35 to 0.12, I2 = 0%, p = 0.36). SGLT-2 inhibitor treatment did not have a significant impact either on SDNN (MD = - 2.83, 95% CI - 7.41 to 1.75, I2 = 31%, p = 0.23), or on r-MSSD (MD = - 0.14, 95% CI - 3.52 to 3.25, I2 = 46%, p = 0.94). Overall risk of bias was graded as low across the selected RCTs. SGLT-2 inhibitor treatment in patients with T2DM does not seem to provide any significant beneficial effect on CAN indices.

The Relationship Between Sexual Activity and Heart Rate Variability in Menopausal Women.

Background:Menopause is an important life stage for women, which can bring along sexual and cardiac problems. Increased heart rate variability is an indicator of parasympathetic activity and is associated with mental and physical health and life expectancy. This study aimed to evaluate the effect of sexual activity (only penile–vaginal intercourse but not masturbation or non-coital sex with a partner) on heart rate variability in healthy menopausal women.Methods:We evaluated 130 menopausal patients aged 45-60 years, without chronic disease. The average weekly sexual activity numbers remembered in the last 1 year were questioned. The patients were divided into 2 groups according to the presence of sexual activity. The sexually active group was divided into subgroups as 1 per week and 2 or more per week. Menopause Rating Scale was applied for menopausal symptoms. Heart rate variability was analyzed from the 24-hour electrocardiography Holter recording.Results:Heart rate variability parameters were higher in the sexually active group than in the sexually inactive group (mean of the standard deviations of all the NN intervals for each 5 min segment of a 24-hour heart rate variability recording: P = .004; root mean square of differences between adjacent normal RR intervals, expressed in ms: P = .001; number of NN intervals exceeding 50 milliseconds: P = .011; percentage of adjacent RR intervals with a difference of duration >50 ms: P = .009; low frequency: P = .011; high frequency: P = .008, low frequency/high frequency: P = .018). When assessed by multiple linear regression analysis by adjusting for age, body mass index, and menopause duration, the variables mean of the standard deviations of all the NN intervals for each 5 min segment of a 24-hour heart rate variability recording, root mean square of differences between adjacent normal RR intervals, expressed in ms, and low frequency were independently associated with the number of sexual activities per week (B = 2.89 ± 1.02, 95% CI = 0.866-4.91, P = .005; B = 4.57 ± 1.83, 95% CI = 0.94-8.2, P = .014; and B = 1174.9 ± 592.2, 95% CI = 2.9-2346.9, P = .049, respectively).Conclusion:In healthy menopausal women, continued sexual activity with penile–vaginal intercourse is associated with better health outcomes on cardiac autonomic function through higher heart rate variability, an index of parasympathetic activity.

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.

Mat Pilates training reduces blood pressure in both well-controlled hypertensive and normotensive postmenopausal women: a controlled clinical trial study

ABSTRACT Aim The aim of this study was to compare the Mat Pilates training-induced responses in resting and ambulatory blood pressure monitoring (ABPM), blood pressure variability (BPV), and heart rate variability (HRV) in well-controlled hypertensive and normotensive postmenopausal women. Methods Forty-seven postmenopausal women were allocated in well-controlled hypertensive (HT) and normotensive (NT) groups. The exercise program was performed three times a week for 12 weeks. Before and after the intervention resting, blood pressure (BP), ABPM, HRV, and BPV were analyzed. Results Student’s t-test showed no difference in baseline anthropometric and resting BP values between groups. The generalized estimation equation (GEE) showed no interactions (group*time), but time (p < .05) reductions in resting systolic, diastolic and mean BP after training in both groups. Sleep ambulatory systolic, diastolic and mean BP were higher overall in the HT group (p < .05 in group effect). We also found a time effect (p < .05) with significant increases in BPV in the mean diurnal and nocturnal deviations weighted for the duration of the daytime and nighttime interval (SDdn) in systolic, diastolic and mean BP, and in the average real variability (ARV) in diastolic and mean in both groups. In addition, HRV increases (p < .05 in time effect) through the percentage of pairs of adjacent RR intervals with a difference of at least 50 ms (pNN50) after training in both groups. Conclusion Both normotensive and well-controlled hypertensive postmenopausal women may have similar Mat Pilates exercise training-induced responses in ambulatory BP, BPV and HRV.

Effects of physical activity on heart rate variability in children and adolescents: a systematic review and meta-analysis.

The aim of the study was to investigate the effects of physical activity (PA) on heart rate variability (HRV) in children and adolescents. We conducted a research of Web of Science, PubMed, ScienceDirect, Springer-Link and EBSCO-host. The revised Newcastle-Ottawa Scale was used in an investigative analysis to assess bias risk. A total of 21 studies were included. Overall, medium-sized associations were found between PA and low frequency and high frequency in children and adolescents. High PA level had significantly higher standard deviation of RR intervals and root of the mean of the sum of the squares of differences between adjacent RR intervals in children and adolescents. The effects of PA on HRV were consistent in children and adolescents. Our systematic review and meta-analysis revealed medium-sized between PA and HRV in children and adolescents. Promoting children's and adolescents' participation in moderate-to-vigorous physical activity (MVPA) will increase parasympathetic nerve activity and decreased sympathetic nerve activity. Our findings support motivating children and adolescents to engage in more MVPA in their daily lives to improve autonomic nervous system function and promote cardiovascular safety.

Evaluation of Sympathetic and Parasympathetic Tone and Reactivity in Adolescents with Specific Learning Disorder (Dyslexia).

To evaluate the autonomic function in specific learning disorder (SLD) and comorbid SLD attention-deficit hyperactivity disorder (SLD-ADHD). A cross-sectional study was conducted in a tertiary care hospital with 20 adolescent subjects each of confirmed SLD, SLD-ADHD, and healthy control (mean age 15.32 y). Heart-rate variability and autonomic-function tests were carried out using standard protocols. Heart-rate variability parameters, viz., mean RR interval, number of RR intervals which differ by ≥ 50ms (NN50), percentage NN50, standard deviation of differences between adjacent RR intervals, root square of mean of the sum of the squares of differences between adjacent RR intervals, coefficient of variance and absolute power of high-frequency band (HF) recorded apparently lower levels in SLD and SLD-ADHD as compared to healthy control indicating lower parasympathetic tone. Whereas, higher absolute power of low- frequency band (LF) in SLD and SLD-ADHD than healthy control indicated enhanced sympathetic activity. Higher LF/HF and lower SD1/SD2 ratios in SLD and SLD-ADHD than healthy control indicated higher sympathetic tone over parasympathetic tone. Values of autonomic-function tests such as E:I ratio, change in heart rate during deep-breathing test, 30:15 ratio, and Valsalva ratio showed a decrease in SLD and SLD-ADHD as compared to healthy control implying reduction in parasympathetic reactivity. Increased values for rise in diastolic blood pressure in the isometric handgrip test and cold pressor test recorded in SLD as compared to healthy control, revealed the increased sympathetic reactivity. Overall, results of heart-rate variability and autonomic-function tests imply dysregulation of sympathetic and parasympathetic activities with sympathetic dominance in SLD and SLD-ADHD.

Low-Intensity Resistance Exercise Combined With Blood Flow Restriction is More Conducive to Regulate Blood Pressure and Autonomic Nervous System in Hypertension Patients-Compared With High-Intensity and Low-Intensity Resistance Exercise.

Background: The effect of resistance exercise on the autonomic nervous system of patients with hypertension has not been identified. Objective: To explore a suitable resistance training method for hypertension patients to regulate blood pressure (BP) and autonomic nervous system function. Method: Forty-five hypertension patients aged between 55 and 70 years were randomly equally divided into three groups: the high-intensity resistance exercise (HE) group, the low-intensity resistance exercise combined with blood flow restriction (LE-BFR) group, and the low-intensity resistance exercise (LE) group. All patients performed quadriceps femoris resistance exercise. The exercise intensity of HE, LE-BFR and LE group was 65, 30 and 30% of one repetition maximum (1RM), respectively. The LE-BFR group used pressure cuffs to provide 130% of systolic pressure to the patient’s thighs during resistance exercise. The training program was 20 times/min/set with a 1-min break after each set, and was conducted five sets/day and 3 days/week, lasting for 12 weeks. The heart rate (HR), BP, root-mean-square of difference-value of adjacent RR intervals (RMSSD), low frequency (LF) and high frequency (HF) were evaluated before and after the first training and the last training. Result: Significant differences in HR were observed in both recovery states after the first and last training (p < 0.01). After 12 weeks of training, the recovery speed of HR in the LE-BFR group increased significantly (p < 0.01). The systolic blood pressures in the HE and LE-BFR group were significantly reduced (p < 0.05 and p < 0.01), and the differences among groups were significant (p < 0.01). In the last recovery state, the RMSSD of the LE group was significantly lower than that in the first recovery state (p < 0.01). The LF/HF ratios of the HE and LE groups in the resting and recovery states were increased significantly (all p < 0.01). LF/HF ratios in the LE-BFR group in the resting and recovery state were decreased significantly (both p < 0.01). Conclusion: Compared to HE and LE, LE-BFR could effectively decrease systolic pressure and regulate the autonomic nervous system function in hypertension patients.

A Feasibility Study Exploring Measures of Autonomic Function in Patients With Failed Back Surgery Syndrome Undergoing Spinal Cord Stimulation

ObjectivesFailed back surgery syndrome (FBSS) is associated with impaired autonomic tone, characterized by sympathetic prevalence and vagal withdrawal. Although spinal cord stimulation (SCS) alleviates pain in FBSS, there is limited research investigating how SCS affects measures of autonomic function. This was a prospective, open-label, feasibility study exploring measures of autonomic function in patients with FBSS receiving SCS therapy. Materials and MethodsA total of 14 patients with FBSS were recruited for baseline measurements and underwent a trial of 10-kHz SCS. There were three failed trials, resulting in the remaining 11 participants receiving a fully implanted 10-kHz SCS system. One participant requested an explant, resulting in ten participants completing both baseline and follow-up (three to six months after SCS implant) measurements. Autonomic function was assessed using time- and frequency-domain heart rate variability (HRV), baroreceptor reflex sensitivity (BRS), and muscle sympathetic nerve activity (MSNA) using microneurography. Because this was a feasibility study, most of the analysis was descriptive. However, paired t-tests and Wilcoxon signed-rank tests tested for differences between baseline and follow-up. ResultsIn the whole (N = 14) and final (N = 10) samples, there was between-participant variation in baseline and follow-up measures. This, combined with a small sample, likely contributed to finding no statistically significant differences in any of the measures between baseline and follow-up. However, plotting baseline and follow-up scores for individual participants revealed that those who showed increases in MSNA frequency, square root of the mean of the squared differences between adjacent RR intervals (RMSSD), percentage of the number of RR intervals >50 ms (pRR50), total power, and up BRS between baseline and follow-up had distinct clustering of baseline values compared with those who showed decreases in these measures. ConclusionsFindings from this feasibility study will aid with informing hypotheses for future research. A key aspect that should be considered in future research concerns exploring the role of baseline measures of autonomic function in influencing change in autonomic function with SCS therapy.

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.

Effect of Transcranial Direct Current Stimulation associated with aerobic exercise on the autonomic modulation of hemiparetic individuals due to stroke: a study protocol for a double-blind randomized controlled trial

Background:Individuals after a stroke have an imbalance in the autonomic nervous system, which increases the risk of death or recurrent episodes of stroke. Transcranial Direct Current Stimulation (tDCS) combined with aerobic exercise has shown an effect on the modulation of this system.Objective:The Heart Rate Variability (HRV) and the distance traveled on the exercise bike will be assessed to verify the additional impact of tDCS combined with aerobic exercise on individuals with chronic stroke sequelae.Methods:The 34 adult individuals with diagnoses of chronic stroke will be randomized into two aerobic exercise intervention groups: G1 (with active tDCS) and G2 (with sham tDCS), three times a week, for 12 weeks.Procedures:tDCS will be implemented during the aerobic exercise with the anodal electrode positioned over the lateral dorsal prefrontal left cortex, and the cathodal electrode over the contralateral supraorbital region, with 2mA, for 20 minutes. Assessments will be carried out pre, immediately after the intervention, and on the 12th, 24th, 36th interventions, and 30 days later.The HRV data that are pulse interval (PI), square root of the mean of the squares of the differences between adjacent normal RR intervals (rMSSD), absolute high frequency (HF), absolute low frequency (LF), high and low frequency ratio (LF / HF) will be collected using a cardio frequency meter. The analysis of the distance traveled on the exercise bike before and after interventions will be analyzed in meters.Discussion:The autonomic control via brain networks after a stroke can be altered and can promote an increase in sympathetic tone, and a higher risk of sudden death or relapse of stroke. It is crucial to demonstrate the effectiveness of available treatments to improve the autonomic function.Trial registration:The study is registered as aBRAZILIAN CLINICAL TEST RECORD(ReBEC): U1111-1222-4588 on the 2018/10/16

Impact of shorter MDR tuberculosis regimen drugs on heart rate variability in MDR tuberculosis patients at tertiary care hospital

Background: Tuberculosis is major cause of death in India. Analysis of heart rate variability is one of the most popular methods of autonomic nervous system evaluation. Shorter MDR-TB regimen drugs affect both central nervous system as well as peripheral nervous system. Existing research suggests that active pulmonary tuberculosis causes ANS dysfunction. So, by HRV measurement impact of shorter MDR-TB regimen drugs on autonomic dysfunction can be correlated. Aim of the current investigation was to evaluate effect of shorter MDR-TB regimen drugs on cardiac autonomic regulation in MDR-TB patients with respect to heart rate variability as a parameter.Methods: Fifty newly diagnosed MDR-TB patients of either gender on shorter MDR- TB regimen were enrolled in this study after taking consent. After 20 minutes rest, ECG was taken by “physiopac digital polygraph” software for 5 minutes. Two follow-up HRV assessments were done on 2nd month and 4th or 6th month of treatment. HRV was calculated by root mean square deviation of successive differences between adjacent RR intervals (RMSSD) and low frequency and high frequency ratio.Results: Repeated measures ANOVA showed no statistically significant difference in HRV parameters between baseline, 2 months and 6 months groups. So, sympathetic and parasympathetic modulation in terms of HRV remains unchanged during treatment of MDR-TB with shorter MDR-TB regimen drugs.Conclusions: Shorter MDR-TB regimen drugs don’t have any significant impact on HRV in MDR- TB patients, No correlation was observed between HRV and heart rate in MDR-TB patients.

Circadian rhythmicity of heart rate variability and its impact on cardiac autonomic modulation in asthma

ABSTRACT The commonly observed nocturnal attack of asthma is accompanied by circadian variations in airway inflammation and other physiological variables. It is also documented to present with a significantly higher risk of adverse cardiovascular events that are associated with lower heart rate variability (HRV) and depressed sympathetic and enhanced parasympathetic modulations. However, available literature is scarce with regard to the impact of alteration in circadian rhythmicity of long-term HRV and its day–night variation in asthmatic patients. Thus, 72-h continuous recording of RR interval and oxygen saturation was done to study the circadian variability of HRV (in terms of time and frequency domain indices) and also to assess the pattern of alterations in sympathetic and parasympathetic tones at different times of the day in asthmatic patients (n = 32) and healthy control subjects (n = 31). Repeated-measure analysis of variance and independent-samples t-test revealed significantly increased parasympathetic tone [in terms of increased square root of the mean squared differences of successive NN intervals (RMSSD), percentage of number of pairs of adjacent RR interval differing by more than 50 ms (pNN50), standard deviation of NN intervals (SDNN), and high frequency (HF)] with reduced sympathetic activity [decreased low frequency (LF) and LF/HF ratio] at early morning hours (between 04:00 and 10:00 h) in the asthma patients in contrast to the healthy subjects who had opposite response. Also, significant phase delay (p<0.05) of all the HRV indices and SpO2, was evident by cosinor analysis. Therefore, disturbed circadian rhythm of HRV indices and early morning increased parasympathetic tone points toward the possible pathophysiological basis of exacerbated asthmatic symptoms at late night/early morning hours and susceptibility of future cardiovascular pathologies. This also necessitates the assessment of HRV rhythm while dealing with the therapeutic management of asthma patients.

Acute hydrogen-rich water ingestion stimulates cardiac autonomic activity in healthy females

Background: Hydrogen-rich water (HRW) has been shown to have a stimulating effect on the human body. Objective: The aim of the study was to assess the influence of acute HRW intake on autonomic cardiac regulation during 50 min of rest sitting. Methods: Fourteen healthy females (age 21.7 ± 1.2 years, body mass 67.8 ± 8.7 kg, height 167 ± 5.5 cm) took part in this double-blind, randomized, placebo-controlled trial with crossover design. Heart rate variability (HRV) was monitored in the sitting position after administration of 1260 ml of HRW or placebo. Time domain indexes of HRV as the square root of the mean of the squares of differences between adjacent RR intervals (RMSSD), the standard deviation of all RR intervals (SDNN) and the ratio of SDNN/RMSSD as an index of sympatho-vagal balance were used to assess autonomic cardiac response. The values were transformed using natural logarithm (Ln). Results: After administration of HRW, we found significantly increased ratio Ln SDNN/RMSSD when comparing it to placebo in 25 min (HRW: 0.40 ± 0.30, placebo: 0.26 ± 0.25, p = .049) and 35 min (HRW: 0.44 ± 0.30, placebo: 0.28 ± 0.28, p = .029) of rest sitting. Ln SDNN was significantly increased after HRW administration when compared to placebo in 45 min (HRW: 4.41 ± 0.42 ms, placebo: 4.28 ± 0.31 ms, p = .049) of rest sitting. Conclusions: Acute HRW ingestion induced a relative increase in sympathetic activity between 25 and 35 min post-ingestion, whereas vagal activity was not affected.

Effect of Transcranial Direct Current Stimulation associated with aerobic exercise on the autonomic modulation of hemiparetic individuals due to stroke: a study protocol for a double-blind randomized controlled trial

Background: Individuals after a stroke have an imbalance in the autonomic nervous system, which increases the risk of death or recurrent episodes of stroke. Transcranial Direct Current Stimulation (tDCS) combined with aerobic exercise has shown an effect on the modulation of this system. Objective: The Heart Rate Variability (HRV) and the distance traveled on the exercise bike will be assessed to verify the additional impact of tDCS combined with aerobic exercise on individuals with chronic stroke sequelae. Methods: The 34 adult individuals with diagnoses of chronic stroke will be randomized into two aerobic exercise intervention groups: G1 (with active tDCS) and G2 (with sham tDCS), three times a week, for 12 weeks. Procedures: tDCS will be implemented during the aerobic exercise with the anodal electrode positioned over the lateral dorsal prefrontal left cortex, and the cathodal electrode over the contralateral supraorbital region, with 2mA, for 20 minutes. Assessments will be carried out pre, immediately after the intervention, and on the 12th, 24th, 36th interventions, and 30 days later. The HRV data that are pulse interval (PI), square root of the mean of the squares of the differences between adjacent normal RR intervals (rMSSD), absolute high frequency (HF), absolute low frequency (LF), high and low frequency ratio (LF / HF) will be collected using a cardio frequency meter. The analysis of the distance traveled on the exercise bike before and after interventions will be analyzed in meters. Discussion: The autonomic control via brain networks after a stroke can be altered and can promote an increase in sympathetic tone, and a higher risk of sudden death or relapse of stroke. It is crucial to demonstrate the effectiveness of available treatments to improve the autonomic function. Trial registration: The study is registered as a BRAZILIAN CLINICAL TEST RECORD (ReBEC): U1111-1222-4588 on the 2018/10/16

Variations of Time Irreversibility of Heart Rate Variability Under Normobaric Hypoxic Exposure.

In the field of biomedicine, time irreversibility is used to describe how imbalanced and asymmetric biological signals are. As an important feature of signals, the direction of time is always ignored. To find out the variation regularity of time irreversibility of heart rate variability (HRV) in the initial stage of hypoxic exposure, the present study implemented 2 h acute normobaric hypoxic exposure on six young subjects who have no plateau or hypoxia experiences; oxygen concentration was set as 12.9%. Electrocardiogram (ECG) signals were recorded in the whole process and RR interval sequences were extracted. Mathematical operations were executed to transform the difference of adjacent RR intervals into proportion and distance with delay time to conduct time irreversibility analysis of HRV. The same calculating method was implemented on six items randomly picked out from the MIT-BIH normal sinus rhythm database as a control group. Results show that variation of time irreversibility of HRV in a hypoxic environment is different from that in a normoxic environment, time irreversibility indices of a hypoxic group decreases continually at a delay time of 1 and 2, and indices curves of time irreversibility gradually tend to be steady and gather with each other at a delay time of 3 or 4. The control group shows no consistent tendency no matter what the delay time is in the range of 1–4. Our study indicates that in short-time hypoxic exposure, as hypoxic time goes by, regulation of the cardiovascular autonomic nervous system weakens; regulation times and intensity of sympathetic and parasympathetic nerves tend to be equal.

Impact of Moderate Exercise Training on Heart Rate Variability in Obese Adults

ABSTRACT Background: Exercise has been shown to improve heart rate variability (HRV) at rest in healthy subjects. HRV response during and immediately after acute exercise in obese individuals following aerobic exercise training has not been evaluated. The purpose of this study was to examine the effect of 12 weeks of moderate intensity aerobic exercise training on HRV during acute exercise and active postexercise recovery in obese individuals. Methods: Eleven obese individuals (5 men, 6 women; body mass index = 39.2 ± 6.3 kg·m−2] underwent 12 weeks of exercise training at 60% of predicted VO2max, determined via a submaximal treadmill test. Body composition was assessed with dual-energy x-ray absorptiometry. HRV was measured during the final minute in each exercise stage and in recovery and analyzed with Kubios HRV software. Results: Predicted VO2max (baseline: 28.2 ± 3.5 mL·kg−1·min−1 and posttraining: 27.4 mL·kg−1·min−1, P &amp;gt; 0.05) was unchanged and body fat % decreased (46.2% ± 2.2 vs 45.5% ± 7.2, respectively). Initial stage heart rate and postexercise recovery heart rate was lower after training. The high frequency component was greater during the initial exercise stage after training. The low frequency component and the standard deviation of instantaneous beat-to-beat variability were greater during the final exercise stage after training. During cooldown, the root-mean-square of differences between adjacent RR intervals and high frequency normalized units were greater after training. Conclusion: HRV markers were improved during acute exercise stage and active recovery in obese individuals following 12 weeks of moderate intensity exercise training. These results suggest improvements in autonomic function can be seen with reductions in adiposity, independent of cardiorespiratory fitness changes in obese adults.

Effects of respiratory muscle training on parasympathetic activity in diabetes mellitus.

This study verified the effects of respiratory muscle training (RMT) on hemodynamics, heart rate (HR) variability, and muscle morphology in rats with streptozotocin-induced diabetes mellitus (DM). Thirty-six male Wistar rats were randomized into 4 groups and 34 completed the study: i) sham-sedentary (Sham-ST; n=9); ii) sham-RMT (Sham-RMT; n=9); iii) DM-sedentary (DM-ST; n=8); and iv) DM-RMT (DM-RMT; n=8). Hemodynamics were assessed by central cannulation, and R-R intervals were measured by electrocardiogram. In addition, the effects of RMT on the cross-sectional area of the diaphragm, anterior tibial, and soleus muscles were analyzed. The induction of DM by streptozotocin resulted in weight loss, hyperglycemia, reduced blood pressure, and attenuated left ventricular contraction and relaxation (P<0.05). We also observed a decrease in root mean square of successive differences between adjacent RR intervals (RMSSD) index and in the cross-sectional area of the muscles assessed, specifically the diaphragm, soleus, and anterior tibial muscles in diabetic rats (P<0.05). Interestingly, RMT led to an increase in RMSSD in rats with DM (P<0.05). The induction of DM produced profound deleterious changes in the diaphragmatic and peripheral muscles, as well as impairments in cardiovascular hemodynamics and autonomic control. Nevertheless, RMT may beneficially attenuate autonomic changes and improve parasympathetic modulation.