Correlation between heart rate variables and the incidence of cardiovascular adverse events in patients with heart failure

Background Chronic heart failure(CHF)is the end-stage manifestation and main cause of death of cardiovascular system diseases.Ventricular arrhythmia is a common complication,which can increase myocardial oxygen consumption,aggravate the disease,and even cause sudden death due to malignant arrhythmia.As a quantitative method to evaluate cardiac autonomic nervous function,heart rate variability is non-invasive and reproducible,and can quantify the risk associated with various cardiac and non-cardiac diseases.The purpose of this study was to analyze the correlation between heart rate variability and the incidence of cardiovascular adverse events in patients with heart failure.Methods 80 patients with heart failure who were treated in our hospital from May 2020 to May 2022 were selected as the study objects.After 3 months of follow-up,patients were divided into occurrence group(n=44)and nonoccurrence group(n=36)according to the occurrence of adverse cardiovascular events(angina pectoris,myocardial infarction,arrhythmia).The index of heart rate variability and the indicators of cardiac function in patients with heart failure was analyzed by one-way analysis of variance(ANOVA).The Key indicators of heart rate variability include standard deviation of normal RR interval(SDNN),mean standard deviation of consecutive 5-minute heartbeat interval(SDANN),square root of mean square of difference between adjacent heartbeat intervals(RMSSD),and percentage of RR intervals differing more than 50 ms from the preceding one(PNN50).The indicators of cardiac function include the New York Heart Association(NYHA)functional classification,left ventricular ejection fraction(LVEF),brain natriuretic peptide(BNP)and cardiac troponin I(c Tn I).Multivariate logistic regression was used to analyze the incidence of cardiovascular adverse events in patients with heart failure.Receiver operating characteristic(ROC)curve was used to analyze the predictive value of heart rate variability in patient outcomes.The correlation between heart rate variability and the incidence of cardiovascular adverse events was analyzed by Kendall's tau-b analysis.Results There were significant differences in SDNN,SDANN,RMSSD,PNN50,cardiac function grade,LVEF and BNP level between the two groups(P<0.05).Through logistic regression analysis,SDNN,SDANN,RMSSD and PNN50 were independent predictors for the incidence of cardiovascular adverse events(P<0.05).The areas under curve for SDNN,SDANN,RMSSD,and PNN50 predicting of the incidence of cardiovascular adverse events were 0.732,0.732,0.758,and 0.819 respectively,and the sensitivity was 77.27%,81.81%,75.00%and 65.91%,respectively.The specificity was 61.11%,61.11%,80.56%,83.33%(P<0.05),respectively.Through Kendall's tau-b analysis,the index of heart rate variability was negatively correlated with the incidence of adverse cardiovascular events in patients with prognosis(P<0.05).Conclusions Heart rate variability has predictive value for the incidence of adverse cardiovascular events in patients with heart failure.The lower the heart rate variability,the higher incidence of cardiovascular adverse events.[S Chin J Cardiol 2024;25(3):135-141]

Ruin Probability with Variable Premium Rate and Disturbed by Diffusion in a Markovian Environment

We consider a risk model with a premium rate which varies with the level of free reserves. In this model, the occurrence of claims is described by a Cox process with Markov intensity process, and the influence of stochastic factors is considered by adding a diffusion process. The integro-differential equation for the ruin probability is derived by a infinitesimal method. Key words ruin probability - variable premium rate - diffusion process - Markov intensity CLC number O 211.9 Foundation item: Supported by the National Natural Science Foundation of China (10071058, 70273029)

Variable Rate Characteristic Waveform Interpolation Speech Coder Based on Phonetic Classification

A variable-bit-rate characteristic waveform interpolation （VBR-CWI） speech codec with about 1.8 kbit/s average bit rate which integrates phonetic classification into characteristic waveform （CW） decomposition is proposed. Each input frame is classified into one of 4 phonetic classes. Non-speech frames are represented with Bark-band noise model. The extracted CWs become rapidly evolving waveforms （REWs） or slowly evolving waveforms （SEWs） in the cases of unvoiced or stationary voiced frames respectively, while mixed voiced frames use the same CW decomposition as that in the conventional CWI. Experimental results show that the proposed codec can eliminate most buzzy and noisy artifacts existing in the fixed-bit-rate characteristic waveform interpolation （FBR-CWI） speech codec, the average bit rate can be much lower, and its reconstructed speech quality is much better than FS 1 016 CELP at 4.8 kbit/s and similar to G. 723.1 ACELP at 5.3 kbit/s.

Finite Time Ruin Probability with Variable Interest Rate and Extended Regular Variation

Consider an insurance risk model, in which the surplus process satisfies a recursive equationU n =U n?1(1+r n )?X n forn≥1, whereU 0=x≥0 is the initial surplus, {r n ;n≥1} the interest rate sequence, {X n ;n≥1} the sequence of i. i. d. real-valued random variables with common distribution functionF, which denotes the gross loss during thenth year. We investigate the ruin probability within a finite time horizon and give the asymptotic result asx→∞. Key words variable interest rate - extend regular variation - finite time ruin probability CLC number O 211.9 Foundation item: Supported by the National Natural Science Foundation of China (10071058, 70273029)Biography: WEI Xiao (1979-), female, Ph. D candidate, research direction: large deviations and its applications, insurance mathematics.

Variable Rate Technology and Cotton Yield Response in Texas

Variable Rate Technology （VRT） takes within-field variability into consideration and aims to match resource application to crop requirement. Even though Texas is the most important cotton producing state in the US, the rate of VRT adoption is very low here. Hence, analyzing the factors influencing the adoption and providing a regional estimate of the impact of VRT adoption on cotton yield is very important. This study used the 2009 Southern Cotton Precision Farming Survey to analyze the farm and farmer characteristics affecting the adoption of VRT among Texas cotton farmers and to empirically estimate the impact of adoption of VRT on cotton yield in Texas. A two-stage least square procedure with a logistic regression model in the first stage and a multiple linear regression model in the second stage was used to analyze the data. The study revealed that there are significant regional differences in adoption pattern within the state of Texas; and the farmers from the coastal region, where there is higher within-field variability, were more likely to adopt VRT compared to other regions. Younger farmers, farmers managing larger farms, and farmers who use computers for farming operations were more likely to adopt VRT. The results also showed that, on an average, the adoption of VRT does not lead to significant yield improvements for cotton in Texas. Since the impact of VRT adoption on yield is not significant, the source of economic advantage of VRT adoption in Texas may be the reduction of input cost.

Development of a Portable Electro-Mechanical Educational Model for Variable Rate Center Pivot Irrigation Technology

Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our team is now developing an Intelligent Center Pivot (ICP) by integrating sensor-based irrigation scheduling with variable rate irrigation technology. However, before this technology can be applied in commercial production, it is necessary to educate growers about its practicality and potential benefits. The objective of this study was to develop a portable tabletop intelligent center pivot model (ICPDemo) to demonstrate and promote adoption of the ICP technology. This paper describes an ICPDemo constructed in 2014, including the design specifications, electro-mechanical design, control strategy, and performance. The ICPDemo has performed according to design specifications and is successfully being used to demonstrate the benefits and effectiveness of ICP technology for irrigation scheduling.

Evaluation of Variable Rate Technology for Fertilizer Application in Permanent Pastures

This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a significant and systematic difference between the application rates of the two discs （about 20%）. This difference had to be corrected by the manufacturer that carried out the necessary changes to the electric actuators. The fertilizer spreader had good distribution homogeneity, considering different working velocities and different positions in the parcel. The pattern distribution curve for 18% super phosphate fertilizer led to an effective working width of 28 meters, with a coefficient of variation of 15%. The longitudinal test, under experimental working conditions led to a machine delay time of 6-7 seconds. The results show an actual fertilization application density between 74%-90% of that determined for each location. These results confirm that the spreader can be used to spread fertilizer differentially in the field.

Quran memorisation and heart rate variability:How do they correlate?

BACKGROUND Heart rate variability(HRV)was shown to be affected by performing religious activities.AIM To examine the relationship between the level of Quran(the holy book of Muslims)memorisation and HRV among teenagers.METHODS This experimental study included 16 Tahfiz students and 16 non-Tahfiz students(n=32).The HRV was measured in three tasks:Recalling familiar verses,memorising new verses,and recalling the newly memorised verses of the Quran.HRV analysis was done using these parameters:Standard deviation of N-N(heartbeat peak)interval;low frequency(LF);high frequency(HF)and LF/HF ratio.RESULTS There were significant differences between tasks for all parameters(P<0.05).However,between the groups,only the LF/HF ratio had significant differences,with F=5.04,P<0.05.Pearson correlation showed a moderate positive correlation between the number of pages memorised and the LF/HF ratio(r=0.61,P<0.05).CONCLUSION Quran memorisation increased the HRV and our results suggested that this activity could be developed as an effective sympathovagal modulation training activity.

A comprehensive review of heart rate variability as an indicator in the regulation of the autonomic nervous system by acupuncture:a bibliometric analysis

This study sought to conduct a bibliometric analysis of acupuncture studies focusing on heart rate variability(HRV)and to investigate the correlation between various acupoints and their effects on HRV by utilizing association rule mining and network analysis.A total of 536 publications on the topic of acupuncture studies based on HRV.The disease keyword analysis revealed that HRV-related acupuncture studies were mainly related to pain,inflammation,emotional disorders,gastrointestinal function,and hypertension.A separate analysis was conducted on acupuncture prescriptions,and Neiguan(PC6)and Zusanli(ST36)were the most frequently used acupoints.The core acupoints for HRV regulation were identified as PC6,ST36,Shenmen(HT7),Hegu(LI4),Sanyinjiao(SP6),Jianshi(PC5),Taichong(LR3),Quchi(LI11),Guanyuan(CV4),Baihui(GV20),and Taixi(KI3).Additionally,the research encompassed 46 reports on acupuncture animal experiments conducted on HRV,with ST36 being the most frequently utilized acupoint.The research presented in this study offers valuable insights into the global research trend and hotspots in acupuncture-based HRV studies,as well as identifying frequently used combinations of acupoints.The findings may be helpful for further research in this field and provide valuable information about the potential use of acupuncture for improving HRV in both humans and animals.

Modeling Dynamical Noises Corrupted Chaotic System for Heart Rate Variability Analysis

It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surroundings. We present an optimization algorithm to find a time series that is as close as possible to the heart rate series subject to the constraint that it is deterministic with respect to some dynamics. The algorithm is tested by some famous forced dynamical systems, and applied to heart rate data. We find that the deterministic components of heart rate variability are chaotic.

Does heart rate variability correlate with long-term prognosis in myocardial infarction patients treated by early revascularization?

AIMTo assess the prevalence of depressed heart rate variability (HRV) after an acute myocardial infarction (MI), and to evaluate its prognostic significance in the present era of immediate reperfusion.METHODSTime-domain HRV (obtained from 24-h Holter recordings) was assessed in 326 patients (63.5 ± 12.1 years old; 80% males), two weeks after a complicated MI treated by early reperfusion: 208 ST-elevation myocardial infarction (STEMI) patients (in which reperfusion was successfully obtained within 6 h of symptoms in 94% of cases) and 118 non-ST-elevation myocardial infarction (NSTEMI) patients (percutaneous coronary intervention was performed within 24 h and successful in 73% of cases). Follow-up of the patients was performed via telephone interviews a median of 25 mo after the index event (95%CI of the mean 23.3-28.0). Primary end-point was occurrence of all-cause or cardiac death; secondary end-point was occurrence of major clinical events (MCE, defined as mortality or readmission for new MI, new revascularization, episodes of heart failure or stroke). Possible correlations between HRV parameters (mainly the standard deviation of all normal RR intervals, SDNN), clinical features (age, sex, type of MI, history of diabetes, left ventricle ejection fraction), angiographic characteristics (number of coronary arteries with critical stenoses, success and completeness of revascularization) and long-term outcomes were analysed.RESULTSMarkedly depressed HRV parameters were present in a relatively small percentage of patients: SDNN < 70 ms was found in 16% and SDNN < 50 ms in 4% of cases. No significant differences were present between STEMI and NSTEMI cases as regards to their distribution among quartiles of SDNN (χ2 =1.536, P = 0.674). Female sex and history of diabetes maintained a significant correlation with lower values of SDNN at multivariate Cox regression analysis (respectively: P = 0.008 and P = 0.008), while no correlation was found between depressed SDNN and history of previous MI (P = 0.999) or number of diseased coronary arteries (P = 0.428) or unsuccessful percutaneous coronary intervention (PCI) (P = 0.691). Patients with left ventricle ejection fraction (LVEF) < 40% presented more often SDNN values in the lowest quartile (P < 0.001). After > 2 years from infarction, a total of 10 patients (3.1%) were lost to follow-up. Overall incidence of MCE at follow-up was similar between STEMI and NSTEMI (P = 0.141), although all-cause and cardiac mortality were higher among NSTEMI cases (respectively: 14% vs 2%, P = 0.001; and 10% vs 1.5%, P = 0.001). The Kaplan-Meier survival curves for all-cause mortality and for cardiac deaths did not reveal significant differences between patients with SDNN in the lowest quartile and other quartiles of SDNN (respectively: P = 0.137 and P = 0.527). Also the MCE-free survival curves were similar between the group of patients with SDNN in the lowest quartile vs the patients of the other SDNN quartiles (P = 0.540), with no difference for STEMI (P = 0.180) or NSTEMI patients (P = 0.541). By the contrary, events-free survival was worse if patients presented with LVEF < 40% (P = 0.001).CONCLUSIONIn our group of patients with a recent complicated MI, abnormal autonomic parameters have been found with a prevalence that was similar for STEMI and NSTEMI cases, and substantially unchanged in comparison to what reported in the pre-primary-PCI era. Long-term outcomes did not correlate with level of depression of HRV parameters recorded in the subacute phase of the disease, both in STEMI and in NSTEMI patients. These results support lack of prognostic significance of traditional HRV parameters when immediate coronary reperfusion is utilised.

Relationship between Ambient Fine Particles and Ventricular Repolarization Changes and Heart Rate Variability of Elderly People with Heart Disease in Beijing, China

Objective To explore the effects of particulate matters less than 2.5 μm in aerodynamic diameter （PM2.5） on heart repolarization/depolarization and heart rate variability （HRV）. Methods We conducted a panel study for elderly subjects with heart disease in Beijing from 2007 to 2008. PM2.5 was measured at a fixed station for 20 h continuously each day while electrocardiogram （ECG） indexes of 42 subjects were also recorded repeatedly. Meteorological data was obtained from the China Meteorological Data Sharing Service System. A mixed linear regression model was used to estimate the associations between PMz.s and the ECG indexes. The model was adjusted for age, body mass index, sex, day of the week and meteorology. Results Significant adverse effects of PM2.5 on ECG indexes reflecting HRV were observed statistically and the strongest effect of PM2.s on HRV was on lag i day in our study. However, there were no associations between PM2.5 and ECG indexes reflecting heart repolarization/depolarization. Additionally, the effects of PM2.5 on subjects with hypertension were larger than on the subjects without hypertension. Conclusion This study showed ambient PM2.5could affect cardiac autonomic function of the elderly people with heart disease, and subjects with hypertension appeared to be more susceptive to the autonomic dysfunction induced by PM2.5.

Heart rate variability： a new tool to predict complications in adult cardiac surgery

Heart rate variability （HRV） refers to the variations between consecutive heartbeats, which depend on the continuous modulation of the sympathetic and parasympathetic branches of the autonomic nervous system. HRV has been shown to be effective as a predictor of risk after myocardial infarction and an early warning sign of diabetic neuropathy, and in the cardiology setting is now recognized to be a useful tool for risk-stratification after hospital admission and after discharge. Recent evidences suggest that HRV analysis might predict complications even in patients undergoing cardiac surgery, and the present review summarizes the importance of HRV analysis in adult cardiac surgery and the perspectives for HRV use in current clinical practice. Although future larger studies are warranted before HRV can be included into daily clinical practice in adult cardiac surgery, HRV is a novel tool which might detect autonomic instability in the early postoperative phase and during hospital stay, thus predicting or prompt-diagnosing many of the post-operative complications.

Heat rate variability and dyssomnia and their correlations to neurological defects in cerebral infarction patients complicated by insomnia A concurrent non-randomized case-control study

BACKGROUND： Heart rate variability refers to the beat-to-beat alteration in heart rate. It is usually a slight periodic variation of R-R intervals. Much information of autonomic nerve system balance can be obtained by measuring the heart rate variability of patients. It remains to be shown whether heart rate variability can be used as an index for determining the severity of insomnia and cerebral infarction. OBJECTIVE： This study aimed to analyze the correlation for each frequency spectrum parameter of heart rate variability with an insomnia index, as well as the degree of neurological defects in patients with simple cerebral infarction and cerebral infarction complicated by insomnia. The goal was to verify the feasibility of frequency spectrum parameters for heart rate variability as a marker for insomnia and cerebral infarction. DESIGN： A case-control observation. SETTING： Department of Neurology, First Hospital Affiliated to China Medical University. PARTICIPANTS： Sixty inpatients, and/or outpatients, with cerebral infarction were admitted to the 202 Hospital of Chinese PLA between December 2005 and October 2006, confirmed by CT, and recruited to the study. According to the insomnia condition （insomnia is defined by a Pittsburgh Sleep Quality Index score 〉 7）, the patients were assigned to a simple cerebral infarction group and a cerebral infarction complicated by insomnia group, with 30 subjects in each group. Thirty additional subjects, who concurrently received examinations and were confirmed to not suffer from cerebral infarction and insomnia, were recruited into the control group. Written informed consent was obtained from each subject for laboratory specimens. The protocol was approved by the Hospital＇s Ethics Committee. METHODS： Following admission, each subject＇s neurological impairment was assessed with the National Institutes of Health Stroke Scale and Pittsburgh Sleep Quality Index. Heart rate variability of each subject was measured with an autonomic nerve analyzer （Weijin Science and Technology Co., Ltd., Taiwan）. Each frequency spectrum parameter of heart rate variability was obtained, including very low frequency, low frequency, high frequency, total power, R-R interval, and its mean square. In addition, percentage of low frequency, high frequency, and ratio of low frequency to high frequency were calculated. For each heart rate frequency spectrum parameter, the difference between groups was analyzed. Moreover, correlations of each frequency spectrum parameter with insomnia and disease condition were analyzed. Data from each index, which were not normally distributed, were processed by logarithmic transformation. The t-test was used for the comparison of intergroup differences. Single-factor linear regression analysis and t-test were used for the analysis of factor-factor correlation and coefficient of correlation, respectively. MAIN OUTCOME MEASURES： （1） Differences of scores in the National Institutes of Health Stroke Scale and Pittsburgh Sleep Quality Index between the simple cerebral infarction group and the cerebral infarction complicated by insomnia group. （2） Differences of heart rate variability parameters between the simple cerebral infarction group and the control group. （3） Correlation of heart rate variability parameters, the Pittsburgh Sleep Quality Index score, and the neurological impairment score. RESULTS： Sixty patients and thirty healthy controls were included in the final analysis. （1） The scores of the Pittsburgh Sleep Quality Index and the neurological impairment were significantly higher in the cerebral infarction complicated by insomnia group compared to the simple cerebral infarction group （P 〈 0.05-0.01）. （2） R-R interval was significantly longer in the simple cerebral infarction group than in the control group, while R-R interval variance and high-frequency band were significantly lower in the simple cerebral infarction group compared to the control group （P 〈 0.05）. （3） For cerebral infarction patients with insomnia, the Pittsburgh Sleep Quality Index score was significantly positively correlated with neurological impairment （r = 0.54, P 〈 0.01）. The low-frequency band, very low-frequency band, high-frequency band, R-R interval variance, total power, R-R interval, and the percentage of high-frequency were significantly negatively correlated with the National Institutes of Health Stroke Scale score （r =4）.45 to 4）.90, P 〈 0.054）.01） and with the Pittsburgh Sleep Quality Index scores （r = 4）.56 to 4）.36, P 〈 0.054）.01）. CONCLUSION： Each heart rate variability parameter can be used as an index for assessing dyssomnia and neurologic impairment （r =4）.56 to 4）.36, P 〈 0.054）.01）.

Effects of Impaired Glucose Metabolism on Heart Rate Variability and Blood Pessure Variability in Essential Hpertensive Patients

To investigate the effects of impaired glucose metabolism （IGM） on cardiovascular autonomic nervous systems in essential hypertensive （EH） patients by comparing heart rate variability （HRV） and blood pressure variability （BPV） in EH patients with or without type 2 diabetes mellitus （T2DM）. Simultaneous 24-h recordings of ambulatory ECG and blood pressure monitoring were performed in 36 male old patients with simple EH and 33 male old patients with EH combined with T2DM. HRV analysis included time domain parameters such as SDNN, SDANN, SDNNi, rMSSD and pNN50, and total spectral power （TP） of HRV, which mainly consists of VLF, LF and HF component along with LF/HF ratio, was also obtained. The value of ambulatory blood pressure was represented as the mean blood pressure （mean systolic/mSBP, diastolic/mDBP and pulse pressure/mPP） during different periods （24 h/24 h, day time/d and night time/n）. Standard deviation （SD） as well as coefficient of variance （CV） of blood pressure during each above-mentioned period were obtained to reflect the long-term BPV. Our result showed that SDNN, SDNNi, SDANN, rMSSD, PNN50, TP and HF of HRV in cases of EH with T2DM were all significantly lower than those in simple EH subjects （P〈0.05）. No significant differences in VLF or LF was found between the two groups （P〉0.05）, while LF/HF ratio was significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.01）. Moreover, dmSBP, 24 h-mPP and dmPP were all significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.05）, while nmSBP, 24 h-mSBP, 24 h-mDBP, dmDBP, nmDBP or nmPP showed no significant difference between this two groups of patients （P〉0.05）. And dSBPSD, dSBPCV and 24 h-SBPSD were all significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.05）, while the other BPV indexes showed no significant difference between this two groups （P〉0.05）. It is concluded that the cardiovascular autonomic nervous systems in EH patients was further impaired by T2DM, displaying lowering of HRV and enlargement of BPV, which in turn induced abnormal structural and functional changes of cardiovascular systems. Therefore, improving cardiovascular autonomic nervous systems might reduce the occurrence of cardiovascular complications in the EH patients with IGM.

Synchronous measurements of prefrontal activity and pulse rate variability during online video game playing with functional near-infrared spectroscopy

Interactions between the central nervous system(CNS)and autonomic nervous system(ANS)play a crucial role in modulating perception,cognition,and emotion production.Previous studies on CNS–ANS interactions,or heart–brain coupling,have often used heart rate variability(HRV)metrics derived from electrocardiography(ECG)recordings as empirical measurements of sympathetic and parasympathetic activities.Functional near-infrared spectroscopy(fNIRS)is a functional brain imaging modality that is increasingly used in brain and cognition studies.The fNIRS signals contain frequency bands representing both neural activity oscillations and heartbeat rhythms.Therefore,fNIRS data acquired in neuroimaging studies can potentially provide a single-modality approach to measure task-induced responses in the brain and ANS synchronously,allowing analysis of CNS–ANS interactions.In this proof-of-concept study,fNIRS was used to record hemodynamic changes from the foreheads of 20 university students as they each played a round of multiplayer online battle arena(MOBA)game.From the fNIRS recordings,neural and heartbeat frequency bands were extracted to assess prefrontal activities and shortterm pulse rate variability(PRV),an approximation for short-term HRV,respectively.Under the experimental conditions used,fNIRS-derived PRV metrics showed good correlations with ECG-derived HRV golden standards,in terms of absolute measurements and video game playing(VGP)-related changes.It was also observed that,similar to previous studies on physical activity and exercise,the PRV metrics closely related to parasympathetic activities recovered slower than the PRV indicators of sympathetic activities after VGP.It is concluded that it is feasible to use fNIRS to monitor concurrent brain and ANS activations during online VGP,facilitating the understanding of VGP-related heart–brain coupling.

Acu-TENS lowers blood lactate levels and enhances heart rate recovery after exercise

Objective:The primary aim of this study is to investigate the effect of application of transcutaneous electrical nerve stimulation over acupuncture points(Acu-TENS)on postexercise blood lactate level.The secondary aim is to explore the effect of Acu-TENS on heart rate recovery and its association with autonomic nervous system.Methods:Twenty healthy subjects(mean age 26.9
1.3)acting as their own controls,were randomized to receive either Acu-TENS or Placebo-TENS as the first of two intervention protocols,implemented one week apart.During Acu-TENS,subjects received 45 min TENS bilaterally over the acupoints Neiguan(PC6).Subjects receiving Placebo-TENS had identical electrode placement but with no electrical output from the TENS unit despite an active output light.Interventions were followed by a 10-min ergometer exercise at 70%age-predicted maximal heart rate.Oxygen consumption and heart rate(HR)were recorded continuously throughout exercise.Blood lactate and blood pressure were taken at 4 time points:prior to,immediately after,at 15-min after exercise,and when HR had returned to baseline values.Results:The post-exercise blood lactate level in the Acu-TENS group was lower than that of the placebo group by 1.12
0.39 mmol/L(p Z 0.01).The Acu-TENS group also had a faster return of HR to pre-exercise level compared to placebo(9.98
4.54 min,p Z 0.047).Heart rate variability analysis inferred reduced sympathetic modulation during exercise after Acu-TENS.There was no between-group difference in post-exercise oxygen consumption.Conclusion:Acu-TENS lowered post-exercise blood lactate level and enhanced heart rate recovery after moderate exercise.The role of Acu-TENS in exercise performance and energy metabolism warrants further investigation.(ClinicalTrails.gov Identifier:NCT01102634)a 2014 Beijing University of Chinese Medicine.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/3.0/).

Power Spectral Analysis of Heart Rate Variability of Driver Fatigue

This investigation was to evaluate the driving fatigue based on power spectral analysis of heart rate variability (HRV) under vertical vibration. Forty healthy male subjects (29.7±3.5 years) were randomly divided into two groups, Group A (28.8±4.3 years) and Group B (30.6±2.7 years). Group A (experiment group) was required to perform the simulated driving and Group B (control group) kept calm for 90 min. The frequency domain indices of HRV such as low frequency (0.04 0.15 Hz, LF), high frequency (0.150.4 Hz, HF), LF/HF together with the indices of hemodynamics such as blood pressure (BP) and heart rate (HR) of the subjects between both groups were calculated and analyzed after the simulated driving. There were significances of the former indices between both groups (P<0.05). All the data collected after experiment of Group A was observed the remarkable linear correlation (P<0.05) and parameters and errors of their linear regression equation were stated (α=0.05, P<0.001) in this paper, respectively. The present study investigated that sympathetic activity of the subjects enhanced after the simulated driving while parasympathetic activities decreased. The sympathovagal balance was also improved. As autonomic function indictors of HRV reflected fatigue level, quantitative evaluation of driving mental fatigue from physiological reaction could be possible.

Analysis of heart rate variability based on singular value decomposition entropy

Assessing the dynamics of heart rate fluctuations can provide valuable information about heart status. In this study, regularity of heart rate variability （HRV） of heart failure patients and healthy persons using the concept of singular value decomposition entropy （SvdEn） is analyzed. SvdEn is calculated from the time series using normalized singular values. The advantage of this method is its simplicity and fast computation. It enables analysis of very short and non-stationary data sets. The results show that SvdEn of patients with congestive heart failure （CHF） shows a low value （SvdEn： 0.056±0.006, p 〈 0.01） which can be completely separated from healthy subjects. In addition, differences of SvdEn values between day and night are found for the healthy groups. SvdEn decreases with age. The lower the SvdEn values, the higher the risk of heart disease. Moreover, SvdEn is associated with the energy of heart rhythm. The results show that using SvdEn for discriminating HRV in different physiological states for clinical applications is feasible and simple.

Altered heart rate variability and pulse-wave velocity after spinal cord injury

BACKGROUND Heart rate variability(HRV) and pulse-wave velocity(PWV),indicators of cardiac function,are altered in patients with spinal cord injury(SCI),suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients.No study has simultaneously investigated HRV and PWV in the same patients.AIM To evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.METHODS In this cross-sectional pilot study,patients with(n = 60) and without SCI(n = 60) were recruited from December 7,2019 to January 21,2020.Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000 P.Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.RESULTS We observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals,square root of the mean sum of squared successive risk ratio interval differences,physical stress index,total power,very-low frequency,low frequency,high frequency,and arterial elasticity.CONCLUSION Patients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without,suggesting that SCI may increase cardiac function loading.