Normal-to-normal Research Articles

Data Analysis of Heart Rate Variability and Arrhythmia in Patients with Paroxysmal Atrial Fibrillation.

Atrial fibrillation (AF) is the most common type of arrhythmia. Heart rate variability (HRV) may be associated with AF risk. The aim of this study was to test HRV indices and arrhythmias as predictors of paroxysmal AF based on 24-hour dynamic electrocardiogram recordings of patients. A total of 199 patients with paroxysmal AF (AF group) and 204 elderly volunteers over 60 years old (Control group) who underwent a 24-hour dynamic electrocardiogram from August 2022 to March 2023 were included. Time-domain indices, frequency-domain indices, and arrhythmia data of the two groups were classified and measured. Binary logistic regression analysis was performed on variables with significant differences to identify independent risk factors. A nomogram prediction model was established, and the sum of individual scores of each variable was calculated. Gender, age, body mass index and low-density lipoprotein (LDL) did not differ significantly between AF and Control groups (p > 0.05), whereas significant group differences were found for smoking, hypertension, diabetes, and high-density lipoprotein (HDL) (p < 0.05). The standard deviation of all normal to normal (NN) R-R intervals (SDNN), standard deviation of 5-minute average NN intervals (SDANN), root mean square of successive NN interval differences (rMSSD), 50 ms from the preceding interval (pNN50), low-frequency/high-frequency (LF/HF), LF, premature atrial contractions (PACs), atrial tachycardia (AT), T-wave index, and ST-segment index differed significantly between the two groups. Logistic regression analysis identified rMSSD, PACs, and AT as independent predictors of AF. For each unit increase in rMSSD and PACs, the odds of developing AF increased by 1.0357 and 1.0005 times, respectively. For each unit increase in AT, the odds of developing AF decreased by 0.9976 times. The total score of the nomogram prediction model ranged from 0 to 110. The autonomic nervous system (ANS) plays a pivotal role in the occurrence and development of AF. The individualized nomogram prediction model of AF occurrence contributes to the early identification of high-risk patients with AF.

P040 Comparisons of Heart Rate Variability Indices Derived from the Sheet-type Device beneath the Mattress with those from the Electrocardiogram

Abstract Introduction A sheet-type device beneath the mattress was developed for non-invasive monitoring of cardiac rhythm during sleep and in bedridden end-of-life elderly patients, enabling the acquisition of ballistocardiography (BCG) signals. BCG represents minute vibrations in the body associated with cardiac ejection of blood and has recently been utilized to estimate heart rate variability (HRV) indices. This study aimed to compare HRV indices derived from BCG with those obtained from simultaneously measured electrocardiogram (ECG) and assess their agreement. Methods Healthy subjects (14 males, 11 females; age 40.6±12.8 yrs.) were recruited between August 2022 and April 2023. Subjects laid on a bed with the device placed under their pillow, while ECG was recorded for 20 minutes. Time-domain indices (mean normal-to-normal (NN) interval) and frequency-domain indices (low frequency (LF) and high frequency (HF)) were calculated, and linear associations were examined by correlation analysis. Bland-Altman analysis was employed to evaluate the agreement between the indices. Results Significant positive associations were observed between BCG and ECG indices in mean NN interval (r=0.994, p&amp;lt;0.001) and LF (r=0.685, p&amp;lt;0.001) and HF (r=0.687, p&amp;lt;0.001). Bland-Altman analysis demonstrated good agreement in mean NN (mean of pairwise difference (MPD): 1.07; limits of agreement (LA): -12.57-14.70; ratio: 0.01), but poor agreement in LF (MPD: -4.32; LA: -30.42-21.78; ratio: 0.63) and HF (MPD: 4.29; LA: -21.70-30.28; ratio: 0.45) based on the ratios (&amp;gt; 0.2). Conclusion The high correlation and good agreement between mean NN intervals suggest that the BCG device can serve as an alternative to HRV for estimating NN interval.

Investigating autonomic nervous system dysfunction among patients with post-COVID condition and prolonged cardiovascular symptoms.

Heart Rate Variability (HRV) and arterial pressure (AP) variability and their responses to head-up tilt test (HUTT) were investigated in Post-COVID-19 syndrome (PCS) patients reporting tachycardia and/or postural hypotension. Besides tachycardia, PCS patients also showed attenuation of the following HRV parameters: RMSSD [square root of the mean of the sum of the squares of differences between adjacent normal-to-normal (NN) intervals] from statistical measures; the power of RR (beat-to-beat interval) spectra at HF (high frequency) from the linear method spectral analysis; occurrence of 2UV (two unlike variation) pattern of RR from the nonlinear method symbolic analysis; and the new family of statistics named sample entropy, when compared to control subjects. Basal AP and LF (low frequency) power of systolic AP were similar between PCS patients and control subjects, while 0 V (zero variation) patterns of AP from the nonlinear method symbolic analysis were exacerbated in PCS patients. Despite tachycardia and a decrease in RMSSD, no parameter of HRV changed during HUTT in PCS patients compared to control subjects. PCS patients reassessed after 6 months showed higher HF power of RR spectra and a higher percentage of 2UV pattern of RR. Moreover, the reassessed PCS patients showed a lower occurrence of 0 V patterns of AP, while the HUTT elicited HR (heart rate) and AP responses identical to control subjects. The HRV and AP variability suggest an autonomic dysfunction with sympathetic predominance in PCS patients. In contrast, the lack of responses of HRV and AP variability indices during HUTT indicates a marked impairment of autonomic control. Of note, the reassessment of PCS patients showed that the noxious effect of COVID-19 on autonomic control tended to fade over time.

Clinical Effect Analysis of Small and Medium Doses of Betaloc Combined with Amiodarone in the Treatment of Ventricular Arrhythmia

Objective: To explore and analyze the clinical effect of small and medium doses of Betaloc combined withamiodarone in the treatment of ventricular arrhythmia. Methods: 60 patients with ventricular arrhythmia that were treated in the Department of Cardiology of our hospital from May 2018–May 2023 were selected for this study, and they were divided into a research group (n = 30) and a reference group (n = 30). The study group was treated with small doses of Betaloc and amiodarone, while the reference group was treated with conventional treatment. The total efficacy of medication, QRS interval, standard deviation of normal-to-normal (NN) intervals (SDNN), root mean square of successive differences between normal heartbeats (RMSSD), standard deviation of the average NN intervals (SDANN), and incidence of adverse reactions were compared between the groups. Results: The effectiveness of medication in the study group was significantly higher than that in the reference group (P &lt; 0.05). Besides, there was no statistically significant difference (P &gt; 0.05) in the QRS interval and SDNN between the two groups before treatment. After treatment, the QRS interval and SDNN of the study group were significantly lower than those of the reference group (P &lt; 0.05). Before treatment, there was no significant difference in RMSSD and SDANN between groups (P &gt; 0.05). After treatment, RMSSD and SDANN in the study group were significantly better than those in the reference group (P &lt; 0.05), and the difference was statisticallysignificant. The incidence of adverse reactions in the study group was significantly lower than that in the reference group (P &lt; 0.05), and the difference was statistically significant. Conclusion: Small doses of Betoprolol and amiodarone is more effective in the treatment of ventricular arrhythmia, which has the value of popularization and application.

Changes in Heart Rate after Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation and Sinus Bradycardia.

This study aimed to evaluate the effect of circumferential pulmonary vein isolation (CPVI) on autonomic nervous function and prognosis in patients with paroxysmal atrial fibrillation (AF) with or without sinus bradycardia.A total of 66 patients with paroxysmal AF accompanied by sinus bradycardia and who underwent CPVI were recruited as the sinus bradycardia group. A total of 91 patients with paroxysmal AF but without sinus bradycardia and who underwent catheter ablation were selected as the control group. After surgical contraindications were eliminated, CPVI was performed by three-dimensional mapping system. 24-hour dynamic electrocardiogram was used to observe the changes of heart rate before and 2 days after surgery.A total of 45 (68%) and 51 (56%) patients in the sinus bradycardia and control groups, respectively, maintained sinus rhythm. There was an increase in heart rate after CPVI in both groups. The standard deviation of normal-to-normal (NN) intervals (SDNN), standard deviation of the average NN intervals (SDANN), low frequency (LF), and LF/high frequency (HF) in the sinus bradycardia and control groups decreased after CPVI (P < 0.01). Moreover, SDANN was higher in patients with sinus bradycardia treated by successful ablation than in those with recurrence (P < 0.01), while SDNN, a standard statistical measure of heart rate variability (rMSSD), LF, and HF were significantly lower in patients with sinus bradycardia (P < 0.05).CPVI was able to produce a significant reduction effect on vagal nerve and sympathetic activity regardless of whether patients with paroxysmal AF had sinus bradycardia. Moreover, CPVI exerted a certain influence on the success rate of AF catheter ablation.

Smartwatch-derived heart rate variability: a head-to-head comparison with the gold standard in cardiovascular disease.

We aimed to investigate the concordance between heart rate variability (HRV) derived from the photoplethysmographic (PPG) signal of a commercially available smartwatch compared with the gold-standard high-resolution electrocardiogram (ECG)-derived HRV in patients with cardiovascular disease. We prospectively enrolled 104 survivors of acute ST-elevation myocardial infarction, 129 patients after an ischaemic stroke, and 30 controls. All subjects underwent simultaneous recording of a smartwatch (Garmin vivoactive 4; Garmin Ltd, Olathe, KS, USA)-derived PPG signal and a high-resolution (1000 Hz) ECG for 30 min under standardized conditions. HRV measures in time and frequency domain, non-linear measures, as well as deceleration capacity (DC) were calculated according to previously published technologies from both signals. Lin's concordance correlation coefficient (ρc) between smartwatch-derived and ECG-based HRV markers was used as a measure of diagnostic accuracy. A very high concordance within the whole study cohort was observed for the mean heart rate (ρc = 0.9998), standard deviation of the averages of normal-to-normal (NN) intervals in all 5min segments (SDANN; ρc = 0.9617), and very low frequency power (VLF power; ρc = 0.9613). In contrast, detrended fluctuation analysis (DF-α1; ρc = 0.5919) and the square mean root of the sum of squares of adjacent NN-interval differences (rMSSD; ρc = 0.6617) showed only moderate concordance. Smartwatch-derived HRV provides a practical alternative with excellent accuracy compared with ECG-based HRV for global markers and those characterizing lower frequency components. However, caution is warranted with HRV markers that predominantly assess short-term variability.

Oxidative stress associated with impaired autonomic control and severity of lung function in chronic obstructive pulmonary disease patients.

Oxidative stress has been suggested to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to investigate a link between malondialdehyde (MDA) levels, pulmonary function, and cardiac autonomic control in patients with COPD. Plasma levels of MDA, heart rate variability, and pulmonary function were measured in 50 clinically stable COPD patients and 50 normal male controls. COPD patients exhibited lower means of the standard deviations of all normal to normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), and high frequency (HF). Nevertheless, they presented greater low frequency (LF) and low frequency/high frequency ratio (LF/HF ratio) in supine and head-up tilt positions than controls (P<0.001). More-over, a negative correlation between MDA levels with SDNN (P<0.001) and a positive correlation with LF (P<0.01) and LF/HF ratio (P<0.05) were observed in both positions. In COPD patients, plasma MDA levels were 2.3 times greater than controls (4.33±2.03 μM vs. 1.89±0.39 μM, P<0.001), and they were inversely correlated with forced vital capacity, forced expiratory volume in 1 sec, midexpiratory flow, and peak expiratory flow (P<0.001). Our findings suggest a potential role for oxidative stress in impaired cardiac autonomic control and clinical relevance of plasma MDA levels as a predictor of severity of COPD in COPD patients.

A Systematic Review of Heart Rate Variability as a Measure of Stress in Medical Professionals.

Understanding the physiological effects of responding to crises is a critical component in understanding how to manage and prepare medical professionals to be crisis responders. Heart rate variability (HRV) is the variation in rate between a succession of R-R intervals. This variation is not only affected by physiological processes such as respiration or metabolic rate but is also directly controlledby the autonomic nervous system. As such, heart rate variability has been proposed as a noninvasive tool to measure the physiological stress response. The aim of this systematic review is to consolidate heart rate variability literature in the context of medical emergencies to determine if heart rate variability changes predictably from baseline when responding to medical crises. This may demonstrate utility as an objective, noninvasive measure of stress response. A systematic literature review of six databases yielded 413 articles, 17 of which met our inclusion criteria of being written in English, measuring HRV in healthcare providers, and measuring HRV in real or simulated medical resuscitations or procedures. Articles were then analyzed using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) scoring system. Out of the 17 articles reviewed, 11 demonstrated statistically significant results showing heart rate variability responding in a predictable manner to stress. Three articles utilized a medical simulation as the stressor, six used medical procedures, and eight used medical emergencies encountered during clinical work. Overall, a predictable trend in heart rate variability metrics of standard deviation from the mean value of normal-to-normal(N-N) intervals (SDNN), root mean square of the successive differences (RMSSD),mean number of times per time interval in which the change in successive normal sinus (N-N) intervals exceeds 50 ms (PNN50), low frequency % (LF%), and low-frequency-to-high-frequency ratio (LF/HF) was observed when responding to stress. This systematic literature review showed that heart rate variability among healthcare providers responding to stressful scenarios follows a predictable pattern of change and expands our understanding of the physiology of stress in healthcare providers. This review supports the use of HRV to monitor stress during high-fidelity simulation to ensure that appropriate physiological arousal is achieved during the training of medical personnel.

Autonomic dysfunction in COVID-19 patients receiving mechanical ventilation: A cross-sectional study

Coronavirus disease 2019 (COVID-19) can damage cardiac tissue by increasing troponin levels and inducing arrhythmias, myocarditis, and acute coronary syndrome. To analyze the impact of COVID-19 on cardiac autonomic control in mechanically ventilated intensive care unit (ICU) patients. This cross-sectional analytical study of ICU patients of both sexes receiving mechanical ventilation was conducted in a tertiary hospital. Patients were divided into COVID-19-positive (COVID(+)) and COVID-19-negative (COVID(-)) groups. Clinical data were collected and heart rate variability (HRV) records obtained using a heart rate monitor. The study sample comprised 82 subjects: 36 (44%) in the COVID(-) group (58.3% female; median age, 64.5 years) and 46 (56%) in the COVID(+) group (39.1% females; median age, 57.5 years). The HRV indices were lower than the reference values. An intergroup comparison identified no statistically significant differences in the mean normal-to-normal (NN) interval, standard deviation of the NN interval, or root mean square of successive differences in NN intervals. The COVID(+) group had an increased low frequency (P = 0.05), reduced high frequency (P = 0.045), and increased low frequency/high frequency (LF/HF) ratio (P = 0.048). There was a weak positive correlation between LF/HF and length of stay in the COVID(+) group. Patients who received mechanical ventilation had lower overall HRV indices. COVID(+) patients who received mechanical ventilation had lower vagal HRV components. These findings likely indicate clinical applicability, as autonomic control impairments are associated with a greater risk of cardiac death.

Effect of Algorithmic Music Listening on Cardiac Autonomic Nervous System Activity: An Exploratory, Randomized Crossover Study.

It is proven that music listening can have a therapeutic impact in many clinical fields. However, to assume a curative value, musical stimuli should have a therapeutic logic. This study aimed at assessing short-term effects of algorithmic music on cardiac autonomic nervous system activity. Twenty-two healthy subjects underwent a crossover study including random listening to relaxing and activating algorithmic music. Electrocardiogram (ECG) and non-invasive arterial blood pressure were continuously recorded and were later analyzed to measure Heart Rate (HR) mean, HR variability and baroreflex sensitivity (BRS). Statistical analysis was performed using a general linear model, testing for carryover, period and treatment effects. Relaxing tracks decreased HR and increased root mean square of successive squared differences of normal-to-normal (NN) intervals, proportion of interval differences of successive NN intervals greater than 50 ms, low-frequency (LF) and high-frequency (HF) power and BRS. Activating tracks caused almost no change or an opposite effect in the same variables. The difference between the effects of the two stimuli was statistically significant in all these variables. No difference was found in the standard deviation of normal-to-normal RR intervals, LFpower in normalized units and LFpower/HFpower variables. The study suggests that algorithmic relaxing music increases cardiac vagal modulation and tone. These results open interesting perspectives in various clinical areas.

Association between Short-Term Exposure to Ozone and Heart Rate Variability: A Systematic Review and Meta-Analysis.

At present, ambient air pollution poses a significant threat to patients with cardiovascular disease (CVD). The heart rate variability (HRV) is a marker of the cardiac autonomic nervous system, and it is related to air pollution and cardiovascular disease. There is, however, considerable disagreement in the literature regarding the association between ozone (O3) and HRV. To further investigate the effects of short-term exposure to O3 on HRV, we conducted the first meta-analysis of relevant studies. The percentage change of HRV indicator(s) is the effect estimate extracted for the quantitative analysis in this study. In our meta-analysis, per 10 ppb increase in O3 was significantly associated with decreases in the time-domain measurements, for standard deviation of the normal-to-normal (NN) interval (SDNN) −1.11% (95%CI: −1.35%, −0.87%) and for root mean square of successive differences (RMSSD) −3.26% (95%CI: −5.42%, −1.09%); in the frequency-domain measurements, for high frequency (HF) −3.01% (95%CI: −4.66%, −1.35%) and for low frequency (LF) −2.14% (95%CI: −3.83%, −0.45%). This study showed short-term exposure to O3 was associated with reduced HRV indicators in adults, which suggested that the cardiac autonomic nervous system might be affected after O3 exposure, contributing to the association between O3 exposure and CVD risk.

Postnatal Protein Intake as a Determinant of Skeletal Muscle Structure and Function in Mice-A Pilot Study.

Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.

Ecg Features of Cardiac Autonomic Neuropathy In Patients With Type 2 Diabetes Mellitus

IntroductionCardiac autonomic neuropathy (CAD) is associated with a poor cardiac prognosis, particularly with an increased risk of sudden death in diabetic patients. A lengthening of the QT interval and alteration of the QT dispersion have been reported in patients with diabetic CAD as well as increased sympathetic activity confirmed by the heart rate variability (HRV) assessment. Material and MethodsWe conducted a randomized study: 77 patients were enrolled in the Sumy Region Affair Hospital, among them 46 had type 2 diabetes mellitus (DM) for 5 years and longer (group A), 31 had normal glucose profile, history of DM was absent (group B). Our patients have been subjected to physical examination, blood tests (glucose, HbA1c, lipid profile), 12-lead ECG with HRV measure. The authors had full access and take responsibility for the integrity of the data. ResultsIt was detected that in patients with DM QTc interval values were close to the upper limits (461.5±26.61ms). The QTc averages of normal-to-normal (NN) intervals (SDANN), root mean square differences of successive NN intervals (RMSSD) and low-frequency (LF) – high-frequency (HF) power ratio were significantly higher in patients with DM (p<0.05). LF/HF was statistically linked to the increase of HbA1c and decrease of magnesium level. It was detected that changes could be improved by the glucose level control and treatment with magnesium supplements 100 mg per day for 30 days (p<0.05). ConclusionCAD is associated with QT prolongation and HRV disturbances. Further research of possible long-term consequences and approaches to their correction is required.

Relationship between heart rate variability, low grade inflammation and glycated hemoglobin. A sugary sweet story

Abstract Background Low grade inflammation (LGI) is significantly associated with microvascular complications in diabetes mellitus (DM). Reduced and impaired Heart rate variability (HRV) is a strong marker of autonomic dysfunction and neuropathy and strongly associated with microvascular disease in DM. New studies and observations indicate that the diabetic neuropathic process starts early during pre-diabetes. On the other hand, HRV and LGI are closely interrelated. Our aim was to evaluate whether LGI or hyperglycemia (i.e. high HbA1c) is associated with the autonomic dysfunction or reduced HRV among people with diabetes and pre-diabetes. Methods and materials This study is based on The Copenhagen Holter Study, in which 678 community dwelling subjects aged 55 – 75 years who were free of previous cardiovascular disease, except from well controlled hypertension, and who underwent a 48-hours Holter recording. Analysis of HRV including night-time HRV were available for 653 participants and this population included 133 people with well-controlled and newly recognized T2DM (mean HbA1c 55 mmol/mol (7.2%)) and 386 people with pre-diabetes defined as HbA1c between 39 mmol/mol (5.7%) and 47 mmol/mol (6.4%). We selected high-sensitive CRP, as markers of LGI. As measures of HRV we used the standard deviation of normal-to-normal (N-N) beats (SDNN), the root mean square of N-N beats (RMSSD) which has been acknowledged to be best linked to vagal parasympathetic tone, and the mean time between N-N complexes (meanNN) which represents the average 24-hour heart rate (60.000/meanNN = average 24-hour HR in beats/min) Results Measures of HRV were associated with HgbA1c among both people with T2DM and pre-diabetes. Among people with pre-diabetes HbA1c was inversely associated with 24-hour RMSSD (r=−0.11, p=0.03) and night-time SDNN (r=−0,13, p&amp;gt;0.01), while among T2DM HgbA1c was only associated with 24-hour RMSSD (r=−0.21, p=0.02). These association stayed significant when adjusted for sex, age, BMI, smoking, HOMA-ir, hs-CRP and systolic blood pressure in multiple linear regression (Table 1). LGI was only associated with HRV in diabetes. HbA1c was not associated with any measures of HRV or LGI among people with normal glucose metabolism. Conclusion HRV is closely and inversely associated with HbA1c in both diabetes and prediabetes, but only in diabetes LGI is associated with HRV. This indicates that the process of autonomic dysfunction/neuropathy starts at an early phase during pre-diabetes and probably provoked by postprandial hyperglycemia, while in diabetes both HbA1c and LGI are associated with HRV showing that LGI is activated later in the disease process probably provoked by long-term postprandial hyperglycemia, indicating treatment of hyperglycemia and postprandial hyperglycemia in the prediabetes state may be helpful. Funding Acknowledgement Type of funding sources: None.

Cardiac Arrhythmias and Impaired Heart Rate Variability in Older Patients With Ventricular Septal Defects.

BackgroundCongenital ventricular septal defects (VSDs) are considered to have benign long‐term outcome when treated correctly in childhood. However, abnormal parameters are described in younger adults, including impaired heart rate variability (HRV). It is not known whether such abnormalities will deteriorate with age. Therefore, HRV and cardiac events, such as premature ventricular contraction, were evaluated in patients aged >40 years with congenital VSDs and compared with healthy peers.Methods and ResultsA total of 30 surgically closed VSDs (51±8 years, repair at median age 6.3 years with total range 1.4–54 years) with 30 healthy controls (52±9 years) and 30 small, unrepaired VSDs (55±12 years) with 30 controls (55±10 years) were all equipped with a Holter monitor for 24 hours. Compared with healthy peers, surgically closed patients had lower SD of the normal‐to‐normal (NN) interbeat interval (129±37 versus 168±38 ms; P<0.01), SD of the average NN intervals for each 5‐minute segment of a 24‐hour HRV recording (116±35 versus 149±35 ms; P<0.01) and 24‐hour triangular index (31±9 versus 44±11; P<0.01). SD of the NN intervals, SD of the average NN intervals for each 5‐minute segment of a 24‐hour HRV recording, and triangular index were comparable between unrepaired VSDs and healthy peers. SD of the NN intervals was <100 ms in 22% of surgically closed and 10% of unrepaired VSDs, whereas controls were within normal ranges. A high number of premature ventricular contractions (>200 events) was registered in 57% of surgical patients compared with 3% of controls (P<0.01), and 53% of unrepaired VSDs compared with 10% in controls (P<0.01).ConclusionsAdults aged >40 with congenital VSDs demonstrate impaired HRV, mainly among surgically closed VSDs. More than half demonstrated a high number of premature ventricular contractions. These novel findings could indicate long‐term cardiovascular disturbances. This necessitates continuous follow‐up of VSDs throughout adulthood.

Effects of exercise training on heart rate variability in children and adolescents with pulmonary arterial hypertension: a pilot study.

Pulmonary arterial hypertension (PAH) is often associated with cardiac autonomic dysfunction, and heart rate variability (HRV) as marker of cardiac autonomic function is even related to disease severity. Knowledge about the effects of physical activity on HRV is limited in these patients. We aimed to assess whether HRV parameters can be influenced by a supervised exercise training program and whether respective changes are related to levels of activity. Six children and adolescents with moderate PAH (3 female, mean age 15.0±4.4 years; mean pulmonary to systemic arterial pressure ratio 0.5±0.2) performed supervised endurance and resistance training for 16 weeks. PAH-specific targeted medication remained unchanged during the study period. HRV was assessed before training and after 16 weeks of training by the use of ECG Move accelerometers. HRV indices included: standard deviation of normal-to-normal (NN) intervals (SDNN), square root of the mean of the sum of the squares of differences between successive NN-intervals (RMSSD), proportion of the number of pairs of successive normal-to-normal intervals that differ by more than 50 ms divided by total number of normal-to-normal interval (pNN50), and the Baevsky stress index (BSI) calculated by the histogram method. Before and after the training program, SDNN, RMSSD and pNN50 correlated with the level of physical activity. Mean values of SDNN, RMSSD and pNN50 did not change significantly due to the training program. Notably, activity level depending SDNN increased markedly after the exercise program (during activity +12.4%, at rest +6.6% and reclining +8.1%, Hedge's g of 0.28, 0.14 and 0.27, respectively). BSI decreased during activity due to the training program reflecting a reduction of stress level (Hedge's g -0.87 indicating an effect of clinical relevance). According to the experience of this pilot study a workout program of 16 weeks revealed an activity level dependent effect on parameters of autonomic cardiac function in children and adolescents with PAH. This mechanism might contribute to the positive effects of exercise training in patients with PAH.

Association Between Postoperative Long-Term Heart Rate Variability and Postoperative Delirium in Elderly Patients Undergoing Orthopedic Surgery: A Prospective Cohort Study.

BackgroundPostoperative delirium (POD) is a common complication after orthopedic surgery in elderly patients. The elderly may experience drastic changes in autonomic nervous system (ANS) activity and circadian rhythm disorders after surgery. Therefore, we intend to explore the relationship between postoperative long-term heart rate (HR) variability (HRV), as a measure of ANS activity and circadian rhythm, and occurrence of POD in elderly patients.MethodsThe study population of this cohort was elderly patients over 60 years of age who scheduled for orthopedic surgery under spinal anesthesia. Patients were screened for inclusion and exclusion criteria before surgery. Then, participants were invited to wear a Holter monitor on the first postoperative day to collect 24-h electrocardiographic (ECG) data. Parameters in the time domain [the standard deviation of the normal-to-normal (NN) intervals (SDNN), mean of the standard deviations of all the NN intervals for each 5-min segment of a 24-h HRV recording (SDNNI), and the root mean square of successive differences of the NN intervals (RMSSD)] and frequency domain [heart rate (HR), high frequency (HF), low frequency (LF), very low frequency (VLF), ultra low frequency (ULF), and total power (TP)] were calculated. Assessment of delirium was performed daily up to the seventh postoperative day using the Chinese version of the 3-Min Diagnostic Interview for CAM-defined Delirium (3D-CAM). The relationship between HRV and POD, as well as the association between HRV and duration of POD, was assessed.ResultsOf the 294 cases that finally completed the follow-up, 60 cases developed POD. Among the HRV parameters, SDNNI, VLF, and ULF were related to the occurrence of POD. After adjustment for potential confounders, the correlation between HRV indices and POD disappeared. Through stratified analysis, two significant negative correlations emerged: ULF in young-old participants and SDNNI, VLF, and ULF in male patients.ConclusionThe lower HRV parameters may be related to the occurrence of POD, and this correlation is more significant in young-old and male patients. ANS disorders and rhythm abnormalities reflected by HRV changes may represent a possible mechanism that promotes POD.

The Association Between Heart Rate Variability and 90-Day Prognosis in Patients With Transient Ischemic Attack and Minor Stroke.

Background: Low heart rate variability (HRV) is known to be associated with increased all-cause, cardiovascular, and cerebrovascular mortality but its association with clinical outcomes in patients with transient ischemic attack (TIA) or minor stroke is unclear.Methods: We selected TIA and minor stroke patients from a prospective registration study. From each continuous electrocardiograph (ECG) record, each QRS complex was detected and normal-to-normal (N-N) intervals were determined. The standard deviation of all N-N intervals (SDNN) and the square root of the mean squared differences of successive N-N intervals (RMSSD) were calculated. Logistic regression analysis and Cox regression analysis were performed to assess the outcomes of patients at 90 days, and the odds and risk ratios (OR/HR) of each index quartile were compared.Results: Compared with SDNN patients in the lowest quartile, neurological disability was significantly reduced in other quartile groups at 90 days, with significant differences [OR of group Q2 was 0.659; 95% confidence interval (CI), 0.482–0.900; p = 0.0088; OR of group Q3 was 0.662; 95% CI, 0.478–0.916; p = 0.0127; OR of group Q4 was 0.441; 95% CI, 0.305–0.639; p <0.0001]. Compared with the lowest quartile, the recurrence rate of TIA or minor stroke in patients of the two higher quartiles (Q3 and Q4) of SDNN was significantly reduced at 90 days (HR of Q3 group was 0.732; 95% CI, 0.539–0.995; p = 0.0461; HR of Q4 group was 0.528; 95% CI, 0.374–0.745; p = 0.0003).Conclusions: Based on our findings, autonomic dysfunction is an adverse indicator for neurological function prognosis and stroke recurrence 90 days after TIA or minor stroke.

The Prognostic Correlation of Heart Rate Variability at Diagnosis with Survival of Patients with Hepatocellular Carcinoma.

Background: Heart rate variability (HRV) indices have been shown to be associated with prognosis in various types of cancer. This study aims to assess the ability of these indices to predict survival in hepatocellular carcinoma (HCC) patients after diagnosis. Methods: We retrospectively collected data from 231 patients diagnosed with HCC between January 2014 and March 2018. The baseline clinical-pathological variables and HRV indices (extracted from Holter electrocardiogram recordings) were analyzed. Results: Univariate and multivariate analyses were performed to identify the predictive value of the above factors for overall survival (OS). The univariate analysis revealed that an age > 60 years, hepatitis C, portal vein involvement (thrombosis), a tumor size > 5 cm, alpha-fetoprotein (AFP) > 400 ng/mL, serum albumin, and C-reactive protein (CRP) were risk factors for poor OS. Multivariable Cox regression analyses identified that a tumor size > 5 cm and AFP > 400 ng/mL predict poorer outcomes in HCC patients. It should be mentioned that, in both the univariate analysis and in the multivariate analysis, between HRV indices, SDNN (standard deviation of all normal-to-normal (NN) intervals) < 110 ms was an independent risk factor for OS with an HR of 3.646 (95% CI 2.143 to 6.205). Conclusion: This study demonstrates that HRV indices identify HCC patients at high risk of death and suggests that such monitoring might guide the need for early therapy in these types of patients, as well as the fact that HRV can be a potential noninvasive biomarker for HCC prognosis.

HRV Features as Viable Physiological Markers for Stress Detection Using Wearable Devices.

Stress has been identified as one of the major causes of automobile crashes which then lead to high rates of fatalities and injuries each year. Stress can be measured via physiological measurements and in this study the focus will be based on the features that can be extracted by common wearable devices. Hence, the study will be mainly focusing on heart rate variability (HRV). This study is aimed at investigating the role of HRV-derived features as stress markers. This is achieved by developing a good predictive model that can accurately classify stress levels from ECG-derived HRV features, obtained from automobile drivers, by testing different machine learning methodologies such as K-Nearest Neighbor (KNN), Support Vector Machines (SVM), Multilayer Perceptron (MLP), Random Forest (RF) and Gradient Boosting (GB). Moreover, the models obtained with highest predictive power will be used as reference for the development of a machine learning model that would be used to classify stress from HRV features derived from heart rate measurements obtained from wearable devices. We demonstrate that HRV features constitute good markers for stress detection as the best machine learning model developed achieved a Recall of 80%. Furthermore, this study indicates that HRV metrics such as the Average of normal-to-normal (NN) intervals (AVNN), Standard deviation of the average NN intervals (SDNN) and the Root mean square differences of successive NN intervals (RMSSD) were important features for stress detection. The proposed method can be also used on all applications in which is important to monitor the stress levels in a non-invasive manner, e.g., in physical rehabilitation, anxiety relief or mental wellbeing.