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1

%HRmax target heart rate is dependent on heart rate performance curve deflection  

Microsoft Academic Search

HOFMANN, P., S. P. VON DUVILLARD, F-J. SEIBERT, R. POKAN, M. WONISCH, L. M. LEMURA, and G. SCHWABERGER. %HRmax target heart rate is dependent on heart rate performance curve deflection. Med. Sci. Sports Exerc., Vol. 33, No. 10, 2001, pp. 1726 -1731. The percent of maximal heart rate (%HRmax) model is widely used to determine training intensities in healthy subjects

PETER HOFMANN; SERGE P. VON DUVILLARD; FRANZ-JOSEF SEIBERT; ROCHUS POKAN; MANFRED WONISCH; LINDA M. LEMURA

2001-01-01

2

Fetal Heart Rate Monitoring during Labor  

MedlinePLUS

... performed? • What happens if the fetal heart rate pattern is abnormal? • Glossary Fetal Heart Rate Monitoring During ... broken). What happens if the fetal heart rate pattern is abnormal? Abnormal fetal heart rate patterns do ...

3

Attentional Focus and Performance Anxiety: Effects on Simulated Race-Driving Performance and Heart Rate Variability  

PubMed Central

Previous studies have demonstrated that an external focus can enhance motor learning compared to an internal focus. The benefits of adopting an external focus are attributed to the use of less effortful automatic control processes, while an internal focus relies upon more effort-intensive consciously controlled processes. The aim of this study was to compare the effectiveness of a distal external focus with an internal focus in the acquisition of a simulated driving task and subsequent performance in a competitive condition designed to increase state anxiety. To provide further evidence for the automatic nature of externally controlled movements, the study included heart rate variability (HRV) as an index of mental effort. Sixteen participants completed eight blocks of four laps in either a distal external or internal focus condition, followed by two blocks of four laps in the competitive condition. During acquisition, the performance of both groups improved; however, the distal external focus group outperformed the internal focus group. The poorer performance of the internal focus group was accompanied by a larger reduction in HRV, indicating a greater investment of mental effort. In the competition condition, state anxiety increased, and for both groups, performance improved as a function of the increased anxiety. Increased heart rate and self-reported mental effort accompanied the performance improvement. The distal external focus group also outperformed the internal focus group across both neutral and competitive conditions and this more effective performance was again associated with lower levels of HRV. Overall, the results offer support for the suggestion that an external focus promotes a more automatic mode of functioning. In the competitive condition, both foci enhanced performance and while the improved performance may have been achieved at the expense of greater compensatory mental effort, this was not reflected in HRV scores.

Mullen, Richard; Faull, Andrea; Jones, Eleri S.; Kingston, Kieran

2012-01-01

4

Heart Rate Variability during Exercise Performed below and above Ventilatory Threshold  

Microsoft Academic Search

COTTIN, F., C. MEDIGUE, P.-M. LEPRETRE, Y. PAPELIER, J.-P. KORALSZTEIN, and V. BILLAT. Heart Rate Variability during Exercise Performed below and above Ventilatory Threshold. Med. Sci. Sports Exerc., Vol. 36, No. 4, pp. 594 - 600, 2004. Purpose: To examine whether differences in heart rate variability (HRV) can distinguish sub- from supra-ventilatory-threshold exercise and whether the exercise duration at supra-threshold

FRANCOIS COTTIN; CLAIRE MEDIGUE; PIERRE-MARIE LEPRETRE; YVES PAPELIER; JEAN-PIERRE KORALSZTEIN; VERONIQUE BILLAT

2004-01-01

5

Target Heart Rates  

MedlinePLUS

... learn how to calculate and monitor your target training heart rate, you have to know your resting heart rate. ... Now you’re ready to determine your target training heart rate. As you exercise, periodically: Take your pulse on ...

6

Longitudinal Changes in Heart Rate-Corrected Measures of Exercise Performance in Children  

Microsoft Academic Search

Interpretation of change in exercise performance over time in children with repaired congenital heart disease is often hampered\\u000a by poor effort that limits the maximum heart rate; this is often difficult to distinguish from chronotropic impairment, a\\u000a common finding in these children. In an attempt to address this limitation, we sought to examine measures of exercise performance\\u000a that are corrected

Kavitha Chintala; Michael L. Epstein; Tajinder P. Singh

2008-01-01

7

REDUCED HEART RATE VARIABILITY IS ASSOCIATED WITH WORSE COGNITIVE PERFORMANCE IN ELDERLY MEXICAN AMERICANS  

PubMed Central

Reduced Heart Rate Variability is a strong predictor of cardiovascular risk factors, cardiovascular events and mortality; and thus may be associated with cognitive neurodegeneration. Yet this has been relatively unexplored, particularly in minority populations with high cardiovascular burden. We used data from the Sacramento Area Latino Study on Aging to examine the cross-sectional association of reduced heart rate variability with cognitive function among elderly Mexican Americans. A total of 869 participants (mean age of 75 years; 59% females) had their 6-minute heart rate variability measured using an ECG monitor and respiration pacer in response to deep breathing. We used the Mean Circular Resultant, known as R bar, as a measure of heart rate variability and categorized it into quartiles (Q1 to Q4 of R bar: reduced to high heart rate variability). Cognitive function was assessed using the Modified Mini Mental State Exam, a 100-point test of global cognitive function and the Spanish and English Verbal Learning Test, a 15-point test of verbal memory recall. In fully-adjusted linear regression models, participants in quartile 1 had a 4-point lower Modified Mini Mental State Exam score (p<0.01), those in quartile 2 had 2-point lower score (p=0.04), and those in quartile 3 had 1-point lower score (p=0.35), as compared to those in the highest quartile of R bar. Reduced R bar was not associated with verbal memory. Our results suggest that reduced heart rate variability is associated with worse performance on the test of global cognitive function, above and beyond traditional cardiovascular risk factors.

Al Hazzouri, Adina Zeki; Haan, Mary N.; Deng, Yingzi; Neuhaus, John; Yaffe, Kristine

2014-01-01

8

Increased heart rate variability and executive performance after aerobic training in the elderly  

Microsoft Academic Search

This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV)\\u000a and on executive performance in older people. Twenty-four sedentary men and women aged 65–78 years were randomly assigned\\u000a to an aerobic exercise program or a stretching program three times a week for 12 weeks. Resting HRV was measured in time and\\u000a frequency domains

Cédric T. Albinet; Geoffroy Boucard; Cédric A. Bouquet; Michel Audiffren

2010-01-01

9

Glucose administration, heart rate and cognitive performance: effects of increasing mental effort  

Microsoft Academic Search

Rationale: It is known that glucose administration is capable of improving performance on tests of declarative verbal memory and non-mnemonic\\u000a tasks requiring high ”mental effort”. At the same time, cognitively demanding tasks are associated with elevated heart rate,\\u000a a response that could feasibly be part of a physiological mechanism serving to increase the delivery of glucose to active\\u000a brain substrates.

David O. Kennedy; Andrew B. Scholey

2000-01-01

10

Heart Rate and Function  

NSDL National Science Digital Library

The purpose of this activity is to discover and learn about heart rate and the function of the heart. The students will investigate whether their hearts beat slower/faster at different times; develop an understanding of why their hearts beat slower/faster at different times; use data to develop an explanation of why their hearts beat slower/faster at different times; be aware of the effect of exercise on respiration; and be able to describe the major function of the heart.

Mr. Mike Peterson (Frazer Public School)

1999-07-01

11

Heart Rate Monitors  

NASA Technical Reports Server (NTRS)

Under a NASA grant, Dr. Robert M. Davis and Dr. William M. Portnoy came up with a new type of electrocardiographic electrode that would enable long term use on astronauts. Their invention was an insulated capacitive electrode constructed of a thin dielectric film. NASA subsequently licensed the electrode technology to Richard Charnitski, inventor of the VersaClimber, who founded Heart Rate, Inc., to further develop and manufacture personal heart monitors and to produce exercise machines using the technology for the physical fitness, medical and home markets. Same technology is on both the Home and Institutional Model VersaClimbers. On the Home Model an infrared heart beat transmitter is worn under exercise clothing. Transmitted heart rate is used to control the work intensity on the VersaClimber using the heart rate as the speedometer of the exercise. This offers advantages to a full range of users from the cardiac rehab patient to the high level physical conditioning of elite athletes. The company manufactures and markets five models of the 1*2*3 HEART RATE monitors that are used wherever people exercise to accurately monitor their heart rate. Company is developing a talking heart rate monitor that works with portable headset radios. A version of the heart beat transmitter will be available to the manufacturers of other aerobic exercise machines.

1990-01-01

12

Target Heart Rate Calculator  

MedlinePLUS

... workout Enter your age to find a target heart rate during exercise. You'll get the most out of your activities by staying within this range of heartbeats/minute. What is your age? years. How to Check Your Heart Rate Right after you stop exercising, take your pulse: ...

13

RELATIONSHIPS BETWEEN HEART RATE AND PHYSIOLOGICAL PARAMETERS OF PERFORMANCE IN TOP-LEVEL WATER POLO PLAYERS  

PubMed Central

The aim of this study was to measure the heart rate (HR) response of eight elite water polo players during the four 7-min quarters of the game and to check for relationships with the physiological parameters of performance (V.O2max, Th1vent, Th2vent). Each athlete performed a V.O2max treadmill test and played a water polo game wearing a heart rate monitor. The game fatigue index was calculated as the ratio of the fourth-quarter HR to the first-quarter HR: HR4/HR1. The results showed a slight decrease in fourth-quarter HR compared with the first quarter, with the mean four-quarter HR equal to 79.9±4.2% of HRmax. Stepwise multiple regression analysis showed V.O2max to be the main explanatory factor of game intensity, i.e. game HR expressed in %HRreserve (R=0.88, P<0.01). We observed that higher aerobic capacity resulted in higher game intensity. We also observed a decrease in the playing intensity in the fourth quarter compared with the first, likely due to very high game involvement. We concluded that high aerobic capacity seems necessary to ensure high game intensity in water polo. This suggests that coaches should encourage their athletes to reach a minimum level of V.O2max and that HR monitoring could be of great interest in the control of water polo training sessions.

Ben Zoubir, S.; Hambli, M.; Chaouachi, A.; Hue, O.; Chamari, K.

2014-01-01

14

Heart Rate Monitor  

NASA Technical Reports Server (NTRS)

In the mid 70's, NASA saw a need for a long term electrocardiographic electrode suitable for use on astronauts. Heart Rate Inc.'s insulated capacitive electrode is constructed of thin dielectric film applied to stainless steel surface, originally developed under a grant by Texas Technical University. HRI, Inc. was awarded NASA license and continued development of heart rate monitor for use on exercise machines for physical fitness and medical markets.

1984-01-01

15

Monitoring changes in physical performance with heart rate measures in young soccer players.  

PubMed

The aim of the present study was to verify the validity of using exercise heart rate (HRex), HR recovery (HRR) and post-exercise HR variability (HRV) during and after a submaximal running test to predict changes in physical performance over an entire competitive season in highly trained young soccer players. Sixty-five complete data sets were analyzed comparing two consecutive testing sessions (3-4 months apart) collected on 46 players (age 15.1 ± 1.5 years). Physical performance tests included a 5-min run at 9 km h(-1) followed by a seated 5-min recovery period to measure HRex, HRR and HRV, a counter movement jump, acceleration and maximal sprinting speed obtained during a 40-m sprint with 10-m splits, repeated-sprint performance and an incremental running test to estimate maximal cardiorespiratory function (end test velocity V (Vam-Eval)). Possible changes in physical performance were examined for the players presenting a substantial change in HR measures over two consecutive testing sessions (greater than 3, 13 and 10% for HRex, HRR and HRV, respectively). A decrease in HRex or increase in HRV was associated with likely improvements in V (Vam-Eval); opposite changes led to unclear changes in V (Vam-Eval). Moderate relationships were also found between individual changes in HRR and sprint [r = 0.39, 90% CL (0.07;0.64)] and repeated-sprint performance [r = -0.38 (-0.05;-0.64)]. To conclude, while monitoring HRex and HRV was effective in tracking improvements in V (Vam-Eval), changes in HRR were moderately associated with changes in (repeated-)sprint performance. The present data also question the use of HRex and HRV as systematic markers of physical performance decrements in youth soccer players. PMID:21656232

Buchheit, M; Simpson, M B; Al Haddad, H; Bourdon, P C; Mendez-Villanueva, A

2012-02-01

16

Assessment of mortality rates for congenital heart defects and surgeons’ performance  

Microsoft Academic Search

Background. In the absence of reliable national data, we have collected results of all operations for congenital heart defects from five departments to assess mortality rates and compare them among surgeons and departments.Methods. Data relating to all operations (2,718) carried out at the five centers during a period from April 1, 1997 through March 31, 1999. Clearly defined criteria were

Jaroslav F Stark; Steve Gallivan; Katie Davis; John R. L Hamilton; James L Monro; James C. S Pollock; Kevin G Watterson

2001-01-01

17

Seasonal changes in physical performance and heart rate variability in high level futsal players.  

PubMed

The aim of this study was to determine the changes in physical performance and resting heart rate variability (HRV) in professional futsal players during the pre-season and in-season training periods. 11 athletes took part in the study (age=24.3±2.9 years; height=176.3±5.2 cm; weight=76.1±6.3 kg), and performed a repeated-sprint ability (RSA) test [6×40 m (20+20 m with a 180° change of direction) sprints separated by 20 s of passive recovery] and Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) at 3 different moments (M1=beginning of pre-season; M2=end of pre-season; M3=mid in-season). The HRV indices were assessed at the same moments. After the short pre-season (3-week), mean RSA time (RSAmean) (M1=7.43±0.2 s; M2=7.24±0.2 s; P=0.003), decrement in RSA performance (RSAdecrement) (M1=6.7±0.3%; M2=5.0±0.9%; P=0.001), and Yo-Yo IR1 distance (M1=1.244±298 m; M2=1.491±396 m; P=0.002) were significantly improved (P<0.05). During the in-season (i. e., M3), performance in Yo-Yo IR1 and RSAmean were maintained. In contrast, RSAbest (M2=6.89±0.2 to M3=6.69±0.3; P=0.001) was improved and RSAdecrement (M2=5.0±0.9% to M3=6.6±0.9%; P=0.001) was impaired. At M2, there was an increase in HRV vagal-related indices compared with M1 that was maintained at M3. In conclusion, after a short pre-season, futsal players improved their RSA and Yo-Yo IR1 performance with concomitant improvements in HRV. These indices were maintained during the in-season period while RSAbest was improved and RSAdecrement impaired. Frequent monitoring of these performances and HRV indices may assist with identification of individual training adaptations and/or early signs of maladaption. PMID:23143705

Oliveira, R S; Leicht, A S; Bishop, D; Barbero-Álvarez, J C; Nakamura, F Y

2013-05-01

18

A higher illuminance induces alertness even during office hours: findings on subjective measures, task performance and heart rate measures.  

PubMed

Nocturnal white light exposure has shown marked results on subjective and objective indicators of alertness, vitality and mood, yet effects of white light during daytime and under usual office work conditions have not been investigated extensively. The current study employed a mixed-group design (N=32), testing effects of two illuminance levels (200lx or 1000lx at eye level, 4000K) during one hour of morning versus afternoon exposure. In four repeated blocks, subjective reports, objective performance and physiological arousal were measured. Results showed effects of illuminance on subjective alertness and vitality, sustained attention in tasks, and heart rate and heart rate variability. Participants felt less sleepy and more energetic in the high versus the low lighting condition, had shorter reaction times on the psychomotor vigilance task and increased physiological arousal. Effects of illuminance on the subjective measures, as well as those on heart rate were not dependent on time of day or duration of exposure. Performance effects were most pronounced in the morning sessions and towards the end of the one-hour exposure period. The effect on heart rate variability was also most pronounced at the end of the one-hour exposure. The results demonstrate that even under normal, i.e., neither sleep nor light deprived conditions, more intense light can improve feelings of alertness and vitality, as well as objective performance and physiological arousal. PMID:22564492

Smolders, K C H J; de Kort, Y A W; Cluitmans, P J M

2012-08-20

19

Determinants of heart rate variability  

Microsoft Academic Search

Objectives. This study sought to examine clinical determinants of heart rate variability and to report normative reference values for eight heart rate variability measures.Background. Although the clinical implications of heart rate variability have been described, clinical determinants and normative values of heart rate variability measures have not been studied systematically in a large community-based population.Methods. The first 2 h of

Hisako Tsuji; Ferdinand J. Venditti; Emily S. Manders; Jane C. Evans; Martin G. Larson; Charles L. Feldman; Daniel Levy

1996-01-01

20

Physiological and performance adaptations to an in-season soccer camp in the heat: associations with heart rate and heart rate variability.  

PubMed

The aim of the present study was to examine the associations between adaptive responses to an in-season soccer training camp in the heat and changes in submaximal exercising heart rate (HRex, 5-min run at 9 ?km/h), postexercise HR recovery (HRR) and HR variability (HRV). Fifteen well-trained but non-heat-acclimatized male adult players performed a training week in Qatar (34.6?±?1.9°C wet bulb globe temperature). HRex, HRR, HRV (i.e. the standard deviation of instantaneous beat-to-beat R-R interval variability measured from Poincaré plots SD1, a vagal-related index), creatine kinase (CK) activity, plasma volume (PV) changes, and post-5-min run rate of perceived exertion (RPE) were collected at six occasions in temperate environmental conditions (22°C). Players also performed the yo-yo intermittent recovery test level 1 (Yo-Yo IR1) in the same environmental conditions (22°C), both at the beginning and at the end of the training week. Throughout the intervention, HRex and HRV showed decreasing (P?performance increased by 7?±?9% (P?=?0.009), which was correlated with changes in HRex [-0.64 (-0.84; -0.28), P?=?0.01]. In conclusion, we found that an in-season soccer training camp in the heat can significantly improve PV and soccer-specific physical performance; both of which are associated with changes in HRex during a 5-min submaximal run. PMID:22092960

Buchheit, M; Voss, S C; Nybo, L; Mohr, M; Racinais, S

2011-12-01

21

Influence of time-varying mean heart rate in coronary artery disease diagnostic performance of heart rate variability indices from exercise stress testing  

Microsoft Academic Search

In this study, the influence of the time-varying mean heart rate (HR) and respiratory frequency in the ability of HR variability (HRV) indices to diagnose coronary artery disease has been studied. The autonomic nervous system activity has been assessed using a methodology that comprises correction of the HRV signal by the time-varying mean HR and redefinition of the classical high-frequency

Raquel Bailón; Pedro Serrano; Pablo Laguna

2011-01-01

22

Correlation between inflection of heart rate\\/work performance curve and myocardial function in exhausting cycle ergometer exercise  

Microsoft Academic Search

Summary  The heart rate\\/work performance (f\\u000ac\\/W) curve is usually S-shaped but a flattening at the top is not always seen. By means of radionuclide ventricular scintigraphy, the left ventricular ejection fraction (LVEF) of 15 sports students was investigated. The behaviour of the f\\u000ac\\/W curve during cycle ergometry with increasing exercise intensities was examined. During exercise, the LVEF showed a

R. Pokan; P. Hofmann; K. Preidler; H. Leitner; J. Dusleag; B. Eber; G. Schwaberger; G. F. Fiiger; W. Klein

1993-01-01

23

Tachycardia | Fast Heart Rate  

MedlinePLUS

... paroxysmal supraventricular tachycardia (PSVT). How it happens Electrical signals in the heart's upper chambers fire abnormally, which interferes with electrical signals coming from the sinoatrial (SA) node --- the heart's ...

24

Instructed heart rate control in a high heart rate population  

Microsoft Academic Search

Forty college students were selected from a large number of introductory psychology students on the basis of high heart rate during an initial screening session. Subjects were then contacted and participated in two additional sessions during which heart rate, respiration rate, and skin conductance measures were obtained. Each session consisted of a baseline period followed by five trial periods during

Craig T. Twentyman; Paul F. Malloy; Alex S. Green

1979-01-01

25

Heart rate control during treadmill exercise.  

PubMed

A computer-controlled treadmill and related data collection and processing systems have been developed for the control of heart rate during treadmill exercise. Minimizing deviations of heart rate from a preset profile is achieved by controlling the speed and/or the gradient of the treadmill. A simple and practical heart rate measurement algorithm has been developed to robustly measure the variations of heart rate. Both conventional Proportional-Integral-Derivative (PID) control and fuzzy Proportional-Integral (PI) control approaches have been employed for the controller design. The fuzzy Proportional-Integral algorithm achieved better heart rate tracking performance. Finally, a heart rate based exercising protocol was successfully implemented on the newly designed exercise system. PMID:17282738

Su, S W; Wang, L; Celler, B G; Savkin, A

2005-01-01

26

Variable Effects of Physical Training of Heart Rate Variability, Heart Rate Recovery, and Heart Rate Turbulence in Chronic Heart Failure  

Microsoft Academic Search

Background: Heart rate variability (HRV), heart rate turbulence (HRT), and heart rate recovery (HRR), indices that reflect autonomic nervous system (ANS) activity, are outcome predictors in patients with chronic heart failure (CHF). It is not clear, however, whether they reflect the same components of ANS activity. No study has examined the effects of physical training (PT) training on HRV, HRT,

EWA PIOTROWICZ; RAFA? BARANOWSKI; MA?GORZATA PIOTROWSKA; TOMASZ ZIELI?SKI; RYSZARD PIOTROWICZ

2009-01-01

27

Heart rate variability: a review  

Microsoft Academic Search

Heart rate variability (HRV) is a reliable reflection of the many physiological factors modulating the normal rhythm of the\\u000a heart. In fact, they provide a powerful means of observing the interplay between the sympathetic and parasympathetic nervous\\u000a systems. It shows that the structure generating the signal is not only simply linear, but also involves nonlinear contributions.\\u000a Heart rate (HR) is

U. Rajendra Acharya; Paul K. Joseph; N. Kannathal; Choo Min Lim; Jasjit S. Suri

2006-01-01

28

Regulation of Human Heart Rate  

NSDL National Science Digital Library

Students learn how to measure heart rate accurately. Then students design and carry out an experiment to test the effects of an activity or stimulus on heart rate, analyze and interpret the data, and present their experiments in a poster session. In this activity students learn about both cardiac physiology and experimental method.

Waldron, Ingrid

29

Prediction of Hospital Acute Myocardial Infarction and Heart Failure 30-Day Mortality Rates Using Publicly Reported Performance Measures  

PubMed Central

Objective To identify an approach to summarizing publicly reported hospital performance data for acute myocardial infarction (AMI) or heart failure (HF) that best predicts current year hospital mortality rates. Setting A total of 1,868 U.S. hospitals reporting process and outcome measures for AMI and HF to the Centers for Medicare and Medicaid Services (CMS) from July 2005 to June 2006 (Year 0) and July 2006 to June 2007 (Year 1). Design Observational cohort study measuring the percentage variation in Year 1 hospital 30-day risk-adjusted mortality rate explained by denominator-based weighted composite scores summarizing hospital Year 0 performance. Data Collection Data were prospectively collected from hospitalcompare.gov. Results Percentage variation in Year 1 mortality was best explained by mortality rate alone in Year 0 over other composites including process performance. If only Year 0 mortality rates were reported, and consumers using hospitals in the highest decile of mortality instead chose hospitals in the lowest decile of mortality rate, the number of deaths at 30 days that potentially could have been avoided was 1.31 per 100 patients for AMI and 2.12 for HF (p < .001). Conclusion Public reports focused on 30-day risk-adjusted mortality rate may more directly address policymakers’ goals of facilitating consumer identification of hospitals with better outcomes.

Aaronson, David S.; Bardach, Naomi S.; Lin, Grace A.; Chattopadhyay, Arpita; Goldman, L. Elizabeth; Dudley, R. Adams

2014-01-01

30

RADIOTELEMETRY OF HEART RATES FROM  

Microsoft Academic Search

A lightweight radiotelemetry system with a range of 80 km was used to monitor heart rate from free-ranging Herring Gulls on flights of up to 20 km. Heart rate varied from 130 beats\\/min in a resting bird to 625 beats\\/min for sustained flight. Soaring birds showed rates similar to those of birds sitting quietly on the ground. Simultaneous records of

JOHN W. mANWISHER; TIMOTHY C. WILLIAMS; JOHN M. TEAL; KENNETH O. LAWSON

1978-01-01

31

Vocalization of Heart Rate Variability.  

National Technical Information Service (NTIS)

In this paper we have proposed vocalization of heart rate variability (HRV) as a perceptual analysis tool. We adapted a phonation-production model to encode external signals and generate audible representations of them. HRV changes caused by induced pertu...

S. Saliu A. Birand G. Kudaiberdieva

2001-01-01

32

Standard for Cardiac Monitors, Heart Rate Meters, and Alarms.  

National Technical Information Service (NTIS)

The standard establishes minimum performance and safety requirements for ECG heart rate monitors intended for critically ill patient monitoring. Subject to this standard are all parts of such monitors that are necessary (a) to obtain a heart rate indicati...

A. A. Schoenberg A. R. Grahn H. E. Booth

1978-01-01

33

The Effects of an Intervention Strategy on Children's Heart Rates and Skill Performance  

ERIC Educational Resources Information Center

The purpose of this project was to examine the effectiveness of a fitness infusion instructional strategy (FI) on children's activity levels and skill performance scores. This strategy included aerobic activity within the skill practice tasks and game play. In other words, students performed short bouts of activity between the practice and…

Ignico, Arlene; Corson, Arleen; Vidoni, Carla

2006-01-01

34

Dimensional Analysis of Heart Rate Variability in Heart Transplant Recipients.  

National Technical Information Service (NTIS)

The authors discuss periodicities in the heart rate in normal and transplanted hearts. The authors then consider the possibility of dimensional analysis of these periodicities in transplanted hearts and problems associated with the record. (ERA citation 1...

J. P. Zbilut G. Mayer-Kress K. Geist

1987-01-01

35

Dimensional analysis of heart rate variability in heart transplant recipients  

SciTech Connect

We discuss periodicities in the heart rate in normal and transplanted hearts. We then consider the possibility of dimensional analysis of these periodicities in transplanted hearts and problems associated with the record.

Zbilut, J.P.; Mayer-Kress, G.; Geist, K.

1987-01-01

36

Heart Rate and Behavior of Twins.  

ERIC Educational Resources Information Center

Genetic and environmental influences on heart rate were studied in samples of twin pairs in middle childhood. Heart rate was measured in resting situation and under two task conditions. Heart rate was related to parental ratings of shyness, emotionality, and selective attention measure. Multivariate analysis suggested that covariance between heart

Boomsma, Dorret I.; Plomin, Robert

1986-01-01

37

Relationship of Hospital Performance with Readmission and Mortality Rates for Patients Hospitalized with Acute Myocardial Infarction, Heart Failure, or Pneumonia  

PubMed Central

Context The Centers for Medicare & Medicaid Services publicly reports hospital 30-day all-cause risk-standardized mortality rates (RSMRs) and 30-day all-cause risk-standardized readmission rates (RSRRs) for acute myocardial infarction (AMI), heart failure (HF), and pneumonia. The relationship between hospital performance as measured by RSMRs and RSRRs has not been well characterized. Objective We determined the relationship between hospital RSMRs and RSRRs overall, and within subgroups defined by hospital characteristics. Design, Setting, and Participants We studied Medicare fee-for-service beneficiaries discharged with AMI, HF, or pneumonia between July 1, 2005 and June 30, 2008. We quantified the correlation between hospital RSMRs and RSRRs using weighted linear correlation; evaluated correlations in groups defined by hospital characteristics; and determined the proportion of hospitals with better and worse performance on both measures. Main Outcome Measures Hospital 30-day RSMRs and RSRRs. Results The analyses included 4506 hospitals for AMI; 4767 hospitals for HF; and 4811 hospitals for pneumonia. The mean RSMRs and RSRRs were 16.60% and 19.94% for AMI; 11.17% and 24.56% for HF; and 11.64% and 18.22% for pneumonia. The correlations (95% confidence intervals [CIs]) between RSMRs and RSRRs were 0.03 (95% CI: ?0.002, 0.06) for AMI, ?0.17 (95% CI: ?0.20, ?0.14) for HF, and 0.002 (95% CI: ?0.03, 0.03) for pneumonia. The results were similar for subgroups defined by hospital characteristics. Although there was a significant negative linear relationship between RSMRs and RSRRs for HF, the shared variance between them was only 2.90% (r2 = 0.029). Conclusions Our findings do not support concerns that hospitals with lower RSMRs will necessarily have higher RSRRs. The rates are not associated for patients admitted with an AMI or pneumonia and only weakly associated, within a certain range, for patients admitted with HF.

Krumholz, Harlan M.; Lin, Zhenqiu; Keenan, Patricia S.; Chen, Jersey; Ross, Joseph S.; Drye, Elizabeth E.; Bernheim, Susannah M.; Wang, Yun; Bradley, Elizabeth H.; Han, Lein F.; Normand, Sharon-Lise T.

2013-01-01

38

Effect of Completion of Cardiac Rehabilitation on Heart Rate Recovery  

Microsoft Academic Search

To evaluate the effects of a cardiac rehabilitation program on heart rate recovery after percutaneous transluminal coronary angioplasty, a historical cohort study was performed on 436 patients of whom 285 were grouped on completion of 5, 10, or 24 training sessions. All 3 groups showed signifi cant improvements in heart rate recovery, peak heart rate during treadmill testing, and end-training

Abbas Soleimani; Mojtaba Salarifar; Seyed E Kasaian; Saeed Sadeghian; Mostafa Nejatian; Ali Abbasi

39

Perceived exertion and heart rate models for estimating metabolic workload in elite British soldiers performing a backpack load-carriage task.  

PubMed

Identifying field measures to estimate backpack load-carriage work intensity in elite soldiers is of interest to the military. This study developed rating of perceived exertion (RPE) and heart rate models to define metabolic workload for a backpack load-carriage task valid for a population of elite soldiers using serial data. Male soldiers (n = 18) from the British Parachute or Special Air Service Regiment completed an incremental treadmill walking and (or) running protocol while carrying a 20-kg backpack. Heart rate, RPE, and oxygen uptake were recorded at each incremental stage of the protocol. Linear mixed models were used to model the RPE and heart rate data in the metric of measured peak oxygen uptake. Workload was accurately estimated using RPE alone (SE = 6.03), percentage of estimated maximum heart rate (%E-MHR) (SE = 6.9), and percentage of measured maximum heart rate (%M-MHR) (SE = 4.9). Combining RPE and %E-MHR resulted in a field measure with an accuracy (SE = 4.9) equivalent to the %M-MHR model. We conclude that RPE, %E-MHR, and %M-MHR provide accurate field-based proxy measures of metabolic workload in elite British soldiers performing a backpack load-carriage task. The model is accurate for the metabolic range measured by these serial data for the backpack load-carriage task. PMID:20962921

Simpson, Richard J; Graham, Scott M; Florida-James, Geraint D; Connaboy, Christopher; Clement, Richard; Jackson, Andrew S

2010-10-01

40

Adaptive prospective ECG-triggered sequence coronary angiography in dual-source CT without heart rate control: Image quality and diagnostic performance.  

PubMed

The aim of this study was to evaluate the accuracy of using second generation dual-source CT (DSCT) to obtain high quality images and diagnostic performance and to reduce the radiation dose in adaptive prospective electrocardiography (ECG)-triggered sequence (CorAdSeq) CT coronary angiography (CTCA) without heart rate control. No prescan ?-blockers were administered. Un-enhanced CT and CTCA with adaptive prospective CorAdSeq scanning without heart rate control were performed in 683 consecutive patients divided into two body mass index (BMI) groups: BMI <25 kg/m(2) (group A, n=412) and BMI ?25 kg/m(2) (group B, n=271). The image quality and quantitative stenosis of all coronary segments with a diameter ?1 mm were assessed. The mean heart rate (MHR), heart rate variability (HRV) and radiation dose values were recorded. In 426 cases, the diagnostic performance was evaluated using quantitative conventional coronary angiography as the reference standard. Diagnostic image quality was obtained in 98.5% of segments in group A and in 98.8% of segments in group B, with no significant differences between the groups. No correlations were observed between the image quality score and MHR or HRV (P=0.492, P=0.564, respectively). The effective radiation doses in groups A and B were 2.57±1.01 mSv and 6.36±1.88 mSv, respectively. The sensitivities and specificities of diagnosing coronary heart disease per patient were 99.6% and 97.8% in group A and 99.5% and 97.5% in group B, respectively (P>0.05). Adaptive prospective CorAdSeq scanning, without heart rate control, by second generation DSCT had a high image quality and diagnostic performance for coronary artery stenosis with lower radiation doses. PMID:23403952

Pan, Chang-Jie; Qian, Nong; Wang, Tao; Tang, Xiao-Qiang; Xue, Yue-Jun

2013-02-01

41

How to Take Your Heart Rate  

MedlinePLUS

... rate for selected ages. For example, the target exercise heart rate range for a 45-year-old will be ... about how hard you should exercise. • Measure your exercise heart rate in beats per minute (described above). • Look at ...

42

A double-blind study on the effects of piracetam upon perceptual and psychomotor performance at varied heart rates in patients treated with artificial pacemakers  

Microsoft Academic Search

Pacemaker-patients have previously been found to have significantly impaired performance in tests of critical flicker fusion (CFF), two-choice reaction time (RT) and vernier visual acuity (KVAT) when the heart rate is reduced from 70 to 45 beats\\/min in sitting position.

Krister Lagergren; Sten Levander

1974-01-01

43

Heart rate variability in weightlifters  

Microsoft Academic Search

On the basis of the literature and original data, heart rate variability (HRV) in weightlifters has been studied. The results\\u000a showed that the distribution mode (a parameter of mathematical analysis that is equal to the most frequent length of RR intervals)\\u000a indicates the intensity of physical exercise. Specific changes in the autonomic balance in athletes as dependent on their\\u000a degree

E. V. Oreshnikov; V. F. Tihonov; T. V. Agafonkina

2009-01-01

44

Analysis of Heart Rate Variability  

Microsoft Academic Search

Spontaneous variability of heart-rate has been related to three major physiological originating factors: quasi-oscillatory fluctuations thought to arise in blood-pressure control, variable frequency oscillations due to thermal regulation, and respiration; frequency selective analysis of cardiac interbeat interval sequences allows the separate contributions to be isolated. Using this method, a laboratory and field study of the effects of mental work load

B. Mc A. SAYKRS

1973-01-01

45

Multifractality and heart rate variability  

NASA Astrophysics Data System (ADS)

In this paper, we participate to the discussion set forth by the editor of Chaos for the controversy, ``Is the normal heart rate chaotic?'' Our objective was to debate the question, ``Is there some more appropriate term to characterize the heart rate variability (HRV) fluctuations?'' We focused on the ~24 h RR series prepared for this topic and tried to verify with two different techniques, generalized structure functions and wavelet transform modulus maxima, if they might be described as being multifractal. For normal and congestive heart failure subjects, the hq exponents showed to be decreasing for increasing q with both methods, as it should be for multifractal signals. We then built 40 surrogate series to further verify such hypothesis. For most of the series (~75%-80% of cases) multifractality stood the test of the surrogate data employed. On the other hand, series coming from patients in atrial fibrillation showed a small, if any, degree of multifractality. The population analyzed is too small for definite conclusions, but the study supports the use of multifractal series to model HRV. Also it suggests that the regulatory action of autonomous nervous system might play a role in the observed multifractality.

Sassi, Roberto; Signorini, Maria Gabriella; Cerutti, Sergio

2009-06-01

46

Heart Rate Indices of Newborn Attentional Responsivity  

ERIC Educational Resources Information Center

Clarifies issues involved in use of heart rate as index of newborn attentional responsivity by reviewing related studies and concluding that heart rate variability can be used in studying attentional responsivity state, and intra-individual and individual variables. (ED)

Porges, Stephen W.

1974-01-01

47

Spider heart-rates and locomotion  

Microsoft Academic Search

1.A non-invasive, laser\\/fibre-optic, technique was developed to measure the heartrates of active unrestrained spiders. The heart-rates of 15 species were measured before, during and after activity.2.Maximum heart-rate varied between species. A possible association between maximum heartrate and prey-catching behaviour is proposed. Within a species, body-weight had no significant effect on maximum heart-rate. InArgyroneta, mature males had significantly higher maximum heart-rates

Clive Bromhall

1987-01-01

48

[Resting heart rate and cardiovascular disease].  

PubMed

Heart rate reflects autonomic nervous system activity. Numerous studies have demonstrated that an increased heart rate at rest is associated with cardiovascular morbidity and mortality as an independent risk factor. It has been shown a link between cardiac autonomic balance and inflammation. Thus, an elevated heart rate produces a micro-inflammatory response and is involved in the pathogenesis of endothelial dysfunction. In turn, decrease in heart rate produces benefits in congestive heart failure, myocardial infarction, atrial fibrillation, obesity, hyperinsulinemia, insulin resistance, and atherosclerosis. Alteration of other heart rate-related parameters, such as their variability and recovery after exercise, is associated with risk of cardiovascular events. Drugs reducing the heart rate (beta-blockers, calcium antagonists and inhibitors of If channels) have the potential to reduce cardiovascular events. Although not recommended in healthy subjects, interventions for reducing heart rate constitute a reasonable therapeutic goal in certain pathologies. PMID:23937816

Brito Díaz, Buenaventura; Alemán Sánchez, José Juan; Cabrera de León, Antonio

2014-07-01

49

An Analysis of Heart Rate Variability  

Microsoft Academic Search

Proceeding from a formal definition of heart rate variability, some mathematical and statistical techniques from sampling statistics and time series analysis for the analytical evaluation of heart rate variability for ergonomics purposes are presented and compared. The concept of sampling statistics gives a measure of heart rate variability, arrived at by combining two measures, which were chosen according to a

H. LUCZAK; W. LAURIG

1973-01-01

50

Heart Rate Control During Treadmill Exercise  

Microsoft Academic Search

A computer-controlled treadmill and related data collection and processing systems have been developed for the control of heart rate during treadmill exercise. Minimizing deviations of heart rate from a preset profile is achieved by controlling the speed and\\/or the gradient of the treadmill. A simple and practical heart rate measurement algorithm has been developed to robustly measure the variations of

S. W. Su; L. Wang; B. G. Celler; A. V. Savkin

2005-01-01

51

Heart rate monitors: State of the art  

Microsoft Academic Search

Heart rate is a useful indicator of physiological adaptation and intensity of effort. Therefore, heart rate monitoring is an important component of cardiovascular fitness assessment and training programmes. The electrocardiogram (ECG) and Holter monitoring devices are accurate, but they are not appropriate for use in field settings due to cost, size and complexity of operation. Lightweight telemetric heart rate monitors

Raija M. T. Laukkanen; Paula K. Virtanen

1998-01-01

52

Increased heteroscedasticity of heart rate in fatal heart failure  

NASA Astrophysics Data System (ADS)

Healthy human heart rate is known to fluctuate in a highly complex manner, displaying complexity characteristics such as those shared by physical systems at a critical state. It is, however, widely believed that chronic heart failure reduces this complexity and that heart rate data from chronic-heart-failure patients can be used for the validation of complexity measures and paradigms applicable both to heart rate and more generally to assess any system's complexity. Here, we counter the above belief, showing an increase in fluctuations and in complexity of heart rate in chronic-heart-failure patients, in particular those at risk of death. This is supported by evidence of increased non-Gaussianity and heteroscedasticity resulting from the emergence of a characteristic correlation scale in the magnitude correlation landscape.

Struzik, Z. R.; Kiyono, K.; Hayano, J.; Watanabe, E.; Yamamoto, Y.

2008-04-01

53

Validation of the Polar Heart Rate Monitor for Assessing Heart Rate During Physical and Mental Stress  

Microsoft Academic Search

The Polar Vantage XL heart rate monitor provides an ambulatory, inexpensive method of continuously measuring heart rate. To examine the validity of the Polar monitor for measuring heart rate during resting periods and while engaging in two stressful tasks, 30 students participated in a 1-hour laboratory session. Heart rates were measured simultaneously using the Polar monitor and electrocardiography (ECG) during

Jeffrey L. Goodie; Kevin T. Larkin; Scott Schauss

2000-01-01

54

Linear and non-linear parameters of heart rate variability during static and dynamic exercise in a high-performance dinghy sailor.  

PubMed

The analysis of heart rate variability (HRV) is recognized as a powerful non-invasive tool to evaluate the influence of autonomic nervous system on the heart and the heart-brain interaction. It is well-known that relatively high HRV is correlated to health condition while low HRV corresponds to cardiovascular disease or could be caused by mental stress, depression or exercise. In order to investigate heart-brain interaction we compare linear and non linear parameters calculated from HRV signals recorded in the same subject at similar heart rate (HR) values, during two different conditions, i.e. static exercise during sailing and dynamic exercise on cycloergometer. In the study, performed in one high-performance would class dinghy sailor, the HR was recorded at rest and during the two types of exercise. For the analysis, tachogram tracts with similar HR values were considered. The power spectral densities in very-low, low (LF) and high (HF) frequency bands were evaluated as well as the LF/HF ratio, the two standard deviations (SD1 and SD2) of the Poincaré plot, the beta values and the fractal dimension (FD). The results indicate a decrease of HRV, LF, HF, SD1 and SD2 parameters, as well as an increase of beta and FD during both types of exercise compared to rest. However, the higher values of LF, LF/HF ratio and SD2 as well as the lower value of FD in upwind sailing in comparison to dynamic exercise on cycloergometer, at similar HR, suggest a different sympatho-vagal modulation on cardiac function and therefore a different heart-brain interaction in these isometric and isotonic exercises. PMID:15133977

Princi, Tanja; Accardo, Agostino; Peterec, Daniel

2004-01-01

55

Effects of bisoprolol on heart rate variability in heart failure  

Microsoft Academic Search

Analysis of heart rate variability (HRV) provides a noninvasive index of autonomic nervous system activity. HRV has been shown to be reduced in heart failure. Preliminary data indicate that ? blockers improve clinical status in patients with heart failure, but HRV improvement remains to be demonstrated. Fifty-four patients from the randomized double-blind, placebo-controlled Cardiac Insufficiency Bisoprolol Study were included in

Francoise Pousset; Xavier Copie; Philippe Lechat; Patrice Jaillon; Jean-Pierre Boissel; Martin Hetzel; Frédéric Fillette; Willem Remme; Louis Guize; Jean-Yves Le Heuzey

1996-01-01

56

Drug Effects on Heart Rate and Heart Rate Variability During a Prolonged Reaction Task.  

National Technical Information Service (NTIS)

The effects of an amphetamine and a barbiturate on heart rate were investigated during long term performance (three hours in a serial reaction task). Besides the interbeat interval (IBI) derived from the successive R-tops of the ECG, the variability of IB...

A. W. K. Gaillard D. A. Trumbo A. J. Krul

1975-01-01

57

Assessment of a circuit of exercises through heart rate response  

Microsoft Academic Search

Objective: A circuit of seven exercises was designed for a cardiac population. This study evaluated whether the patients achieved their training heart rate during the circuit, recommended to be 70–85% of the maximum heart rate achieved during an exercise test. Design: Patients were randomly allocated to a starting exercise to balance any order effect from performing the exercises in a

Jose Marcelino; Michele Harms

1995-01-01

58

Heart rate during training and competition for longdistance running  

Microsoft Academic Search

Heart rate monitors are used widely by scientists, coaches and sports participants to monitor heart rate during physical activity. Although there are data that show that heart rate monitors measure heart rate accurately during a range of physical activities, there is less consensus on the interpretation of heart rate data. The day-to-day variation in heart rate under controlled submaximal exercise

M. I. Lambert; Z. H. Mbambo; A. St Clair Gibson

1998-01-01

59

Acoustically based fetal heart rate monitor  

NASA Technical Reports Server (NTRS)

The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.

Baker, Donald A.; Zuckerwar, Allan J.

1991-01-01

60

Heart Rate and Reinforcement Sensitivity in ADHD  

ERIC Educational Resources Information Center

Background: Both theoretical and clinical accounts of attention-deficit/hyperactivity disorder (ADHD) implicate a dysfunctional reinforcement system. This study investigated heart rate parameters in response to feedback associated with reward and response cost in ADHD children and controls aged 8 to 12. Methods: Heart rate responses (HRRs)…

Luman, Marjolein; Oosterlaan, Jaap; Hyde, Christopher; van Meel, Catharina S.; Sergeant, Joseph A.

2007-01-01

61

Heart rate and heart rate variability responses to Tai Chi and jogging in Beijing and Graz  

PubMed Central

Background: Tai Chi is a famous training method in China, and jogging is a popular kind of exercise both in Austria and China. Nevertheless, there is little information concerning online monitoring of biosignals during both training activities in parallel. Within the last years innovative scientific monitoring tools for evaluating features of neurocardial fitness have been developed. Aims: The goal of this study was to demonstrate heart rate and heart rate variability analysis for the first time during Tai Chi and jogging. Volunteers and Methods: Continuous electrocardiographic monitoring over a period of 75 minutes was performed simultaneously in two healthy volunteers using the same type of equipment (medilog AR12 systems). Two healthy persons (both male, 49 years and 52 years, respectively), both hobby sportsmen, were monitored continuously during two resting periods before and after active sport and also during Tai Chi and jogging, respectively. Results: Data acquisition was performed without any technical problems in both subjects. Poincaré plots of sequential R-R intervals (beat to beat variability) show two ellipses of different shape and magnitude. During resting periods blood pressure effects can be clearly seen in one subject (jogging). The same effects, however reduced, are obvious in the other volunteer during Tai Chi. Conclusions: The present investigations during Tai Chi and jogging highlight the potential value of heart rate and heart rate variability monitoring even under difficult conditions. The innovative kind of analysis helps to show how well the human body reacts to sport, stress and recovery.

Litscher, Gerhard; Zhang, Weibo; Huang, Tao; Wang, Lu

2011-01-01

62

PREDICTING MAXIMAL HEART RATE USING AGE, RESTING HEART RATE, AND WEIGHT  

Microsoft Academic Search

Ebnet E, Kosinski E, Menges K, Rice M, Rudy K. Predicting Maximal Heart Rate using Age, Resting Heart Rate, and Weight. Journal of Undergraduate Kinesiology Research. 2006; 2(1): 15-20. Purpose: The purpose of this study was to develop an accurate, yet concise, maximal heart rate (HRmax) prediction equation with a standard error of less than ±7 beats per minute using

TOM EBNET; EMILY KOSINSKI; KATIE MENGES; MELISSA RICE; KAYLA RUDY

63

Heart Rate Variability Analysis in the Assessment of Autonomic Function in Heart Failure.  

National Technical Information Service (NTIS)

Heart rate is not static but rather changes continuously in response to physical and mental demands. In fact, an invariant heart rate is associated with disease processes such as heart failure. Heart rate variability analysis is a noninvasive technique us...

M. J. De Jong D. C. Randall

2004-01-01

64

Heart rate changes during electroconvulsive therapy  

PubMed Central

Background This observational study documented heart rate over the entire course of electrically induced seizures and aimed to evaluate the effects of stimulus electrode placement, patients' age, stimulus dose, and additional predictors. Method In 119 consecutive patients with 64 right unilateral (RUL) and 55 bifrontal (BF) electroconvulsive treatments, heart rate graphs based on beat-to-beat measurements were plotted up to durations of 130 s. Results In RUL stimulation, the initial drop in heart rate lasted for 12.5 ± 2.6 s (mean ± standard deviation). This depended on stimulus train duration, age, and baseline heart rate. In seizures induced with BF electrode placement, a sympathetic response was observed within the first few seconds of the stimulation phase (median 3.5 s). This was also the case with subconvulsive stimulations. The mean peak heart rate in all 119 treatments amounted to 135 ± 20 bpm and depended on baseline heart rate and seizure duration; electrode placement, charge dose, and age were insignificant in regression analysis. A marked decline in heart rate in connection with seizure cessation occurred in 71% of treatments. Conclusions A significant independent effect of stimulus electrode positioning on cardiac action was evident only in the initial phase of the seizures. Electrical stimulation rather than the seizure causes the initial heart rate increase in BF treatments. The data reveal no rationale for setting the stimulus doses as a function of intraictal peak heart rates (‘benchmark method’). The marked decline in heart rate at the end of most seizures is probably mediated by a baroreceptor reflex.

2013-01-01

65

Heart to Heart: Using Heart Rate Telemetry to Meet Physical Education Outcomes.  

ERIC Educational Resources Information Center

Presents a foundation for establishing measurable physical education outcomes, demonstrating how heart rate telemetry can help measure and achieve such outcomes. After explaining heart rate telemetry function, the article examines student and teacher outcomes that could be included in school physical education outcomes and achieved using heart

Deal, Tami Benham; Deal, Laurence O.

1995-01-01

66

Metaiodobenzylguanidine and heart rate variability in heart failure.  

PubMed

It is assumed that the low-frequency power (LF) of heart rate variability (HRV) increases with progress of congestive heart failure (CHF), therefore positively correlating with cardiac 123I-metaiodobenzylguanidine (MIBG) washout. It is demonstrated here that HRV, including normalized LF, correlated inversely with MIBG washout and positively with the ratio of heart-to-mediastinum MIBG activity in controls and CHF patients, whereas these correlations were not observed within CHF patients. Thus MIBG washout may increase and HRV including normalized LF may decrease with CHF, although the HRV and MIBG measures may not similarly change in proportion to the severity of the cardiac autonomic dysfunction in CHF. PMID:9805260

Kurata, C; Shouda, S; Mikami, T; Uehara, A; Ishikawa, K; Tawarahara, K; Nakano, T; Matoh, F; Takeuchi, K

1998-10-01

67

Association between heart rate variability and manual pulse rate  

PubMed Central

Introduction: One model for neurological assessment in chiropractic pertains to autonomic variability, tested commonly with heart rate variability (HRV). Since HRV may not be convenient to use on all patient visits, more user-friendly methods may help fill-in the gaps. Accordingly, this study tests the association between manual pulse rate and heart rate variability. The manual rates were also compared to the heart rate derived from HRV. Methods: Forty-eight chiropractic students were examined with heart rate variability (SDNN and mean heart rate) and two manual radial pulse rate measurements. Inclusion criteria consisted of participants being chiropractic students. Exclusion criteria for 46 of the participants consisted of a body mass index being greater than 30, age greater than 35, and history of: a) dizziness upon standing, b) treatment of psychiatric disorders, and c) diabetes. No exclusion criteria were applied to the remaining two participants who were also convenience sample volunteers. Linear associations between the manual pulse rate methods and the two heart rate variability measures (SDNN and mean heart) were tested with Pearson’s correlation and simple linear regression. Results: Moderate strength inverse (expected) correlations were observed between both manual pulse rate methods and SDNN (r = ?0.640, 95% CI ?0.781, ?0.435; r = ?0.632, 95% CI ?0.776, ?0.425). Strong direct (expected) relationships were observed between the manual pulse rate methods and heart rate derived from HRV technology (r = 0.934, 95% CI 0.885, 0.962; r = 0.941, 95% CI 0.897, 0.966). Conclusion: Manual pulse rates may be a useful option for assessing autonomic variability. Furthermore, this study showed a strong relationship between manual pulse rates and heart rate derived from HRV technology.

Hart, John

2013-01-01

68

Heart rate variability and its relation to ventricular arrhythmias in congestive heart failure  

Microsoft Academic Search

BACKGROUND--It has been shown that heart rate variability is decreased in patients with congestive heart failure and that depressed heart rate variability is associated with a propensity to ventricular arrhythmias. Little is known, however, about heart rate variability in patients with both congestive heart failure and ventricular arrhythmias. METHODS--Spectral heart rate variability was analysed from 24 hour ambulatory electrocardiograms in

L. Fei; P. J. Keeling; J. S. Gill; Y. Bashir; D. J. Statters; J. Poloniecki; W. J. McKenna; A. J. Camm

1994-01-01

69

Multivariable analysis of heart rate recovery after cycle ergometry in heart failure: Exercise in heart failure  

Microsoft Academic Search

PurposeThe purpose of this study was to investigate the association between impairment in heart rate recovery (HRrec) after cycle ergometry and prognostic markers in patients with heart failure (HF) compared with healthy controls.

Melissa Jehn; Martin Halle; Tibor Schuster; Henner Hanssen; Friedrich Koehler; Arno Schmidt-Trucksäss

2011-01-01

70

Heart rate and oxygen uptake response to exercise in children with low peak exercise heart rate  

Microsoft Academic Search

Normal children achieve the same increase of oxygen uptake (VO2) in response to exercise even though resting and submaximal exercise heart rates vary greatly as a function of age, body size and physical conditioning. To determine whether the VO2 response to exercise is altered when heart rate is significantly reduced by heart disease, we compared 78 children who achieved a

I. M. Schulze-Neick; H. U. Wessel; M. H. Paul

1992-01-01

71

Human heart rate variability and sleep stages  

Microsoft Academic Search

With the aim of better understanding the dynamic changes in sympatho-vagal tone occurring during the night, human heart rate variability (HRV) during the various sleep stages was evaluated by means of autoregressive spectral analysis.

L. Toscani; P. F. Gangemi; A. Parigi; R. Silipo; P. Ragghianti; E. Sirabella; M. Morelli; L. Bagnoli; R. Vergassola; G. Zaccara

1996-01-01

72

Biofeedback heart rate training during exercise  

Microsoft Academic Search

Eighteen healthy human subjects participated in weekly sessions of five 10-minute trials of walking on a treadmill at 2.5 mph and 6% grade. Eight experimental subjects received beat-to-beat heart rate biofeedback during the exercise and were instructed to try to lower their heart rates; ten control subjects did not receive feedback. By the end of 5 weeks (25 trials), the

David S. Goldstein; Richard S. Ross; Joseph V. Brady

1977-01-01

73

Ear Acupressure, Heart Rate, and Heart Rate Variability in Patients with Insomnia  

PubMed Central

This high-tech “teleacupuncture study” describes a neurovegetative ear acupressure effect in patients with chronic insomnia by using heart rate variability analysis. Heart rate (HR) and heart rate variability (HRV) measurements in 31 patients (mean age?±?SD: 54.3?±?10.6 years) were performed under standardized conditions in Harbin, China, and the data analysis was performed in Graz, Austria. Similar to our previous clinical and basic teleacupuncture research works, the electrocardiograms (ECGs) were recorded by an HRV Medilog AR12 system during ear acupressure of the Shenmen point on the left ear. HR decreased significantly (P < 0.05) during and after acupressure stimulation. The effect was not visible after the first stimulation, rather it appeared in the phase following the second acupressure stimulation (10 min after the first stimulation). Total HRV showed significant stimulation-dependent increases (P < 0.05), immediately after each acupressure stimulation with a maximum after the third stimulation (20 min after the first stimulation), but there was no long-lasting effect. The present results can serve as a solid basis for the further investigations of auricular point stimulation for noninvasive complementary use in treating insomnia.

Wang, Lu; Cheng, Weiping; Sun, Zhongren; Xu, Yangyang; Cheng, Guangyu; Kuang, Haixue

2013-01-01

74

What is the "normal" fetal heart rate?  

PubMed Central

Aim. There is no consensus about the normal fetal heart rate. Current international guidelines recommend for the normal fetal heart rate (FHR) baseline different ranges of 110 to 150 beats per minute (bpm) or 110 to 160 bpm. We started with a precise definition of “normality” and performed a retrospective computerized analysis of electronically recorded FHR tracings. Methods. We analyzed all recorded cardiotocography tracings of singleton pregnancies in three German medical centers from 2000 to 2007 and identified 78,852 tracings of sufficient quality. For each tracing, the baseline FHR was extracted by eliminating accelerations/decelerations and averaging based on the “delayed moving windows” algorithm. After analyzing 40% of the dataset as “training set” from one hospital generating a hypothetical normal baseline range, evaluation of external validity on the other 60% of the data was performed using data from later years in the same hospital and externally using data from the two other hospitals. Results. Based on the training data set, the “best” FHR range was 115 or 120 to 160 bpm. Validation in all three data sets identified 120 to 160 bpm as the correct symmetric “normal range”. FHR decreases slightly during gestation. Conclusions. Normal ranges for FHR are 120 to 160 bpm. Many international guidelines define ranges of 110 to 160 bpm which seem to be safe in daily practice. However, further studies should confirm that such asymmetric alarm limits are safe, with a particular focus on the lower bound, and should give insights about how to show and further improve the usefulness of the widely used practice of CTG monitoring.

Pildner von Steinburg, Stephanie; Boulesteix, Anne-Laure; Lederer, Christian; Grunow, Stefani; Schiermeier, Sven; Hatzmann, Wolfgang; Schneider, Karl-Theodor M.

2013-01-01

75

Heart Rate Variability and Blood Pressure during Dynamic and Static Exercise at Similar Heart Rate Levels  

PubMed Central

Aim was to elucidate autonomic responses to dynamic and static (isometric) exercise of the lower limbs eliciting the same moderate heart rate (HR) response. Method: 23 males performed two kinds of voluntary exercise in a supine position at similar heart rates: static exercise (SE) of the lower limbs (static leg press) and dynamic exercise (DE) of the lower limbs (cycling). Subjective effort, systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP) and the time between consecutive heart beats (RR-intervals) were measured. Time-domain (SDNN, RMSSD), frequency-domain (power in the low and high frequency band (LFP, HFP)) and geometric measures (SD1, SD2) as well as non-linear measures of regularity (approximate entropy (ApEn), sample entropy (SampEn) and correlation dimension D2) were calculated. Results: Although HR was similar during both exercise conditions (88±10 bpm), subjective effort, SBP, DBP, MAP and RPP were significantly enhanced during SE. HRV indicators representing overall variability (SDNN, SD 2) and vagal modulated variability (RMSSD, HFP, SD 1) were increased. LFP, thought to be modulated by both autonomic branches, tended to be higher during SE. ApEn and SampEn were decreased whereas D2 was enhanced during SE. It can be concluded that autonomic control processes during SE and DE were qualitatively different despite similar heart rate levels. The differences were reflected by blood pressure and HRV indices. HRV-measures indicated a stronger vagal cardiac activity during SE, while blood pressure response indicated a stronger sympathetic efferent activity to the vessels. The elevated vagal cardiac activity during SE might be a response mechanism, compensating a possible co-activation of sympathetic cardiac efferents, as HR and LF/HF was similar and LFP tended to be higher. However, this conclusion must be drawn cautiously as there is no HRV-marker reflecting “pure” sympathetic cardiac activity.

Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Stoll, Regina; Kreuzfeld, Steffi

2013-01-01

76

Monofractality in RR Heart Rate by Multifractal Tools  

NASA Astrophysics Data System (ADS)

Multifractal formalism is tested if it can work as a robust estimator of monofractals when scaling intervals are fixed. Intervals for scaling are selected to be consistent with known frequency bands of power spectral analysis used in estimates of heart rate variability: low frequency (LF), very low frequency (VLF), and ultra low frequency (ULF). Tests on fractional Brownian motions and a binomial cascade are performed to validate popular multifractal methods: Wavelet Transform Modulus Maxima and Multifractal Detrended Fluctuation Analysis. Then the methods are applied to identify monofractal elements of control processes driving the heart rate. A transition is found in the dynamic organization of autonomic nervous system control of the heart rate related to the change in scaling intervals. The control over the diurnal heart rate is of a multifractal type when considered in LF and of a monofractal type when observed in ULF. Additionally, this transition affects on a switch in a relation between widths of diurnal and nocturnal multifractal spectra.

Makowiec, D.; Dudkowska, A.; Ga??ska, R.; Rynkiewicz, A.; Wdowczyk-Szulc, J.

2009-05-01

77

Heart-rate pulse-shift detector  

NASA Technical Reports Server (NTRS)

Detector circuit accurately separates and counts phase-shift pulses over wide range of basic pulse-rate frequency, and also provides reasonable representation of full repetitive EKG waveform. Single telemeter implanted in small animal monitors not only body temperature but also animal movement and heart rate.

Anderson, M.

1974-01-01

78

Heart Rate Conditioning in Newborn Infants: Relationships Among Conditionability, Heart Rate Variability, and Sex  

ERIC Educational Resources Information Center

Trace conditioning was evaluated in newborn infants by measurements of heart rate responses to a conditioned stimulus in anticipation of or in absence of the unconditioned stimulus. Data suggest females have higher levels of heart rate variability than males, which parallels their greater conditionability. (GO)

Stamps, Leighton E.; Porges, Stephen W.

1975-01-01

79

Heart Rate Variability in Athletes  

Microsoft Academic Search

athletes from training status, different types of exercise training, sex and ageing, presented from both cross-sectional and longitudinal studies. The predictability of HRV in over-training, athletic condition and athletic performance is also included. Finally, some recommendations concerning the application of HRV methods in athletes are made. The cardiovascular system is mostly controlled by autonomic regulation through the activity of sympathetic

Bert Seps; Frank Beckers

2003-01-01

80

Digital heart rate measurement based on Atmega16L  

NASA Astrophysics Data System (ADS)

The photoelectric heart rate meter reported in this paper picks up heart rate signals with a photoelectric cell, converts them into standard TTL pulse signal, and sends them into the input capture interface of a single-chip computer Atmega16L. Its input capture register can capture the Timer/Counter value at a given external (edge triggered) event on the input capture pin (ICP1) of T/C1. The counter number is sent into T/C1's input capture register ICR1 after the voltage of the input capture pin ICP1 jumped according to the program setting. The single-chip computer catches the input pulse signal as some numerical values of Timer/Counter (T/C1) and works out a single heart rate cycle and displays by three seven segment tubes, which are the peripheral equipments of the single-chip computer. ICCAVR integrated compiler is applied to assemble and compile the software programs of the heart rate meter. After the programs compiled successfully, a HEX file is produced and downloaded into the single chip computer by software SLISP. This photoelectric heart rate meter can measure the people heart rate efficiently with measurement range of 10-200 times per minute, precision of +/- 1%, low cost and reliable performance.

Zhang, Xiaoqing; Feng, Lishuang; Wang, Jiqiang

2008-03-01

81

Heart Rate and Lactate Levels during Weight-Training Exercise in Trained and Untrained Men.  

ERIC Educational Resources Information Center

A study of effects of squatting exercise on heart rate and blood lactate levels in trained and untrained males indicated that trained subjects performed more work and had higher heart rates and lactate levels at exhaustion untrained subjects, though heart rate and lactate levels were lower for trained subjects at a given bar mass or submaximal…

Stone, Michael H.; And Others

1987-01-01

82

Heart rate variability in systemic hypertension  

Microsoft Academic Search

Low heart rate (HR) variability is a risk factor for cardiac mortality in various patient populations, but it has not been well established whether patients with long-standing hypertension have abnormalities in the autonomic modulation of HR. Time and frequency domain measures of HR variability were compared in randomly selected, age-matched populations of 188 normotensive and 168 hypertensive males (mean age

Heikki V. Huikuri; Antti Ylitalo; Sirkku M. Pikkujämsä; Markku J. Ikäheimo; K. E. Juhani Airaksinen; Asko O. Rantala; Mauno Lilja; Y. Antero Kesäniemi

1996-01-01

83

Heart Rate Preceding Motility in Sleep.  

National Technical Information Service (NTIS)

Heart rate (HR) increases before movement in sleep have been attributed to vascular congestion resulting from maintenance of a constant body position for a long period of time. An alternative hypothesis is that movements during sleep may be regulated by s...

R. E. Townsend L. C. Johnson P. Naitoh A. G. Muzet

1975-01-01

84

Lessons from the Heart: Individualizing Physical Education with Heart Rate Monitors.  

ERIC Educational Resources Information Center

Learning about the relationship between heart rate and physical activity is an important aspect of fitness education. Use of a heart rate monitor (HRM) helps a student to understand how stretching and large muscle movements gradually increase the heart rate and blood flow, and enables students to measure their exercise heart rates and set goals…

Kirkpatrick, Beth; Birnbaum, Burton H.

85

Discrimination power of long-term heart rate variability measures for chronic heart failure detection  

Microsoft Academic Search

The aim of this study was to investigate the discrimination power of standard long-term heart rate variability (HRV) measures\\u000a for the diagnosis of chronic heart failure (CHF). The authors performed a retrospective analysis on four public Holter databases,\\u000a analyzing the data of 72 normal subjects and 44 patients suffering from CHF. To assess the discrimination power of HRV measures,\\u000a an

Paolo Melillo; Roberta Fusco; Mario Sansone; Marcello Bracale; Leandro Pecchia

2011-01-01

86

Gaussian Mixture Model of Heart Rate Variability  

PubMed Central

Heart rate variability (HRV) is an important measure of sympathetic and parasympathetic functions of the autonomic nervous system and a key indicator of cardiovascular condition. This paper proposes a novel method to investigate HRV, namely by modelling it as a linear combination of Gaussians. Results show that three Gaussians are enough to describe the stationary statistics of heart variability and to provide a straightforward interpretation of the HRV power spectrum. Comparisons have been made also with synthetic data generated from different physiologically based models showing the plausibility of the Gaussian mixture parameters.

Costa, Tommaso; Boccignone, Giuseppe; Ferraro, Mario

2012-01-01

87

Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability  

Microsoft Academic Search

BackgroundPrevious studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development.

Linda E. May; Alan Glaros; Hung-Wen Yeh; James F. Clapp III; Kathleen M. Gustafson

2010-01-01

88

Autonomic control of heart rate after exercise in trained wrestlers.  

PubMed

The objective of this study was to establish differences in vagal reactivation, through heart rate recovery and heart rate variability post exercise, in Brazilian jiu-jitsu wrestlers (BJJW). A total of 18 male athletes were evaluated, ten highly trained (HT) and eight moderately trained (MT), who performed a maximum incremental test. At the end of the exercise, the R-R intervals were recorded during the first minute of recovery. We calculated heart rate recovery (HRR60s), and performed linear and non-linear (standard deviation of instantaneous beat-to-beat R-R interval variability - SD1) analysis of heart rate variability (HRV), using the tachogram of the first minute of recovery divided into four segments of 15 s each (0-15 s, 15-30 s, 30-45 s, 45-60 s). Between HT and MT individuals, there were statistically significant differences in HRR60s (p <0.05) and in the non linear analysis of HRV from SD130-45s (p <0.05) and SD145-60s (p <0.05). The results of this research suggest that heart rate kinetics during the first minute after exercise are related to training level and can be used as an index for autonomic cardiovascular control in BJJW. PMID:24744476

Henríquez, Olguín C; Báez, San Martín E; Von Oetinger, A; Cañas, Jamett R; Ramírez, Campillo R

2013-06-01

89

Streaming updates for heart rate variability algorithms.  

PubMed

Heart rate variability (HRV) quantifies the fluctuations of the lengths of consecutive heart beat intervals, and is a reliable descriptor of many physiological factors modulating the normal rhythm of the heart. As the heart rate signal is nonstationary, indicators deduced from it may be present at all times, but may also occur episodically at nonpredetermined time instances. The potential for real-time feedback long-term ambulatory recordings is thus apparent. Numerous methods for measuring HRV have been standardized and are in active use, but are typically not designed to operate at real time. In this paper, we study the most popular HRV quantification methods and propose streaming algorithms that maximally utilize previously computed information without altering the output of the methods. We demonstrate speedups of more than two orders of magnitude for typical use-case scenarios. Using our algorithms on embedded systems that compute HRV leads to dramatic decreases in power consumption and in some cases allows for computation of metrics that were not previously possible at real time. PMID:24956611

Stergiou, Stergios; Balakrishnan, Rajalakshmi

2014-07-01

90

Heart rate variability during cycloergometric exercise or judo wrestling eliciting the same heart rate level  

Microsoft Academic Search

This study compared heart rate variability (HRV) in ten male judokas between two types of exercise eliciting the same near-maximal average heart rate (HR): judo wrestling vs. cycloergometric bout. Beat-to-beat RR intervals were recorded during (1) a 4-min judo randori (wrestling); (2) a 4-min cycloergometric exercise eliciting maximal oxygen consumption ( V?O 2MAX). Time series were analyzed both by short

François Cottin; François Durbin; Yves Papelier

2004-01-01

91

Heart Rate Variability - A Historical Perspective  

PubMed Central

Heart rate variability (HRV), the beat-to-beat variation in either heart rate or the duration of the R–R interval – the heart period, has become a popular clinical and investigational tool. The temporal fluctuations in heart rate exhibit a marked synchrony with respiration (increasing during inspiration and decreasing during expiration – the so called respiratory sinus arrhythmia, RSA) and are widely believed to reflect changes in cardiac autonomic regulation. Although the exact contributions of the parasympathetic and the sympathetic divisions of the autonomic nervous system to this variability are controversial and remain the subject of active investigation and debate, a number of time and frequency domain techniques have been developed to provide insight into cardiac autonomic regulation in both health and disease. It is the purpose of this essay to provide an historical overview of the evolution in the concept of HRV. Briefly, pulse rate was first measured by ancient Greek physicians and scientists. However, it was not until the invention of the “Physician’s Pulse Watch” (a watch with a second hand that could be stopped) in 1707 that changes in pulse rate could be accurately assessed. The Rev. Stephen Hales (1733) was the first to note that pulse varied with respiration and in 1847 Carl Ludwig was the first to record RSA. With the measurement of the ECG (1895) and advent of digital signal processing techniques in the 1960s, investigation of HRV and its relationship to health and disease has exploded. This essay will conclude with a brief description of time domain, frequency domain, and non-linear dynamic analysis techniques (and their limitations) that are commonly used to measure HRV.

Billman, George E.

2011-01-01

92

Spectral analysis of heart rate variability signal during sleep stages  

Microsoft Academic Search

The authors investigated the autonomic nervous activity during sleep stages by means of power spectrum density of heart rate variability signal. Spectral estimation was performed by autoregressive modelling of RR series. The data obtained suggest an augmented sympathetic activity during REM sleep and a progressive decrease of it when passing from awake state to stages 1,2,3-4

G. Calcagnini; G. Biancalana; F. Giubilei; S. Strano; S. Cerutti

1994-01-01

93

Abnormal heart rate variability in essential hypertension  

Microsoft Academic Search

Abnormal autonomic regulation may contribute to blood pressure elevation in arterial hypertension. This may be reflected in altered heart rate variability (HRV). During rest variations around 0.10 Hz predominantly reflect sympathetic nervous activity and to some extent parasympathetic activity. Variations around 0.30 Hz almost exclusively reflect parasympathetic activity.The aim of the present study was to compare HRV in patients with

Line B. Madsen; Dorthe S. Møller; Jens K. Rasmussen; Ole Nyvad; Erling B. Pedersen

2005-01-01

94

Clustering Fetal Heart Rate Tracings by Compression  

Microsoft Academic Search

Fetal heart rate (FHR) monitoring, before and during labor, is a very\\u000aimportant medical practice in the detection of fetuses in danger. We clustered\\u000aFHR tracings by compression in order to identify abnormal ones. We use a\\u000arecently introduced approach based on algorithmic information theory, a\\u000atheoretical, rigorous and well-studied notion of information content in\\u000aindividual objects. The new method

C. Costa Santos; Paul M. B. Vitányi; Luis Antunes

2006-01-01

95

Modeling heart rate variability by stochastic feedback  

NASA Technical Reports Server (NTRS)

We consider the question of how the cardiac rhythm spontaneously self-regulates and propose a new mechanism as a possible answer. We model the neuroautonomic regulation of the heart rate as a stochastic feedback system and find that the model successfully accounts for key characteristics of cardiac variability, including the 1/f power spectrum, the functional form and scaling of the distribution of variations of the interbeat intervals, and the correlations in the Fourier phases which indicate nonlinear dynamics.

Amaral, L. A.; Goldberger, A. L.; Stanley, H. E.

1999-01-01

96

Quantitative analysis of heart rate variability  

Microsoft Academic Search

In the modern industrialized countries every year several hundred thousands of people diedue to the sudden cardiac death. The individual risk for this sudden cardiac death cannot bedefined precisely by common available, non-invasive diagnostic tools like Holter-monitoring,highly amplified ECG and traditional linear analysis of heart rate variability (HRV). Therefore,we apply some rather unconventional methods of nonlinear dynamics to analyse the

J. Kurths; A. Voss; P. Saparin; A. Witt; H. J. Kleiner; N. Wessel

1995-01-01

97

Heart rate variability in familial Mediterranean fever  

Microsoft Academic Search

Familial Mediterranean fever (FMF) is a hereditary disease, characterized by recurrent episodes of fever and polyserositis.\\u000a Heart rate variability (HRV) is a powerful, simple and reliable technique to evaluate autonomic nervous system function. Previous\\u000a studies of physiologic parameters during tilt-test have suggested that patients with FMF have abnormal cardiovascular reactivity\\u000a and occult dysautonomia. Prompted by these findings, the present study

Naomi Nussinovitch; Avi Livneh; Keren Katz; Pnina Langevitz; Olga Feld; Moshe Nussinovitch; Benjamin Volovitz; Merav Lidar; Udi Nussinovitch

2011-01-01

98

Passive fetal heart rate monitoring apparatus and method with enhanced fetal heart beat discrimination  

NASA Technical Reports Server (NTRS)

An apparatus for acquiring signals emitted by a fetus, identifying fetal heart beats and determining a fetal heart rate. Multiple sensor signals are outputted by a passive fetal heart rate monitoring sensor. Multiple parallel nonlinear filters filter these multiple sensor signals to identify fetal heart beats in the signal data. A processor determines a fetal heart rate based on these identified fetal heart beats. The processor includes the use of a figure of merit weighting of heart rate estimates based on the identified heart beats from each filter for each signal. The fetal heart rate thus determined is outputted to a display, storage, or communications channel. A method for enhanced fetal heart beat discrimination includes acquiring signals from a fetus, identifying fetal heart beats from the signals by multiple parallel nonlinear filtering, and determining a fetal heart rate based on the identified fetal heart beats. A figure of merit operation in this method provides for weighting a plurality of fetal heart rate estimates based on the identified fetal heart beats and selecting the highest ranking fetal heart rate estimate.

Zahorian, Stephen A. (Inventor); Livingston, David L. (Inventor); Pretlow, III, Robert A. (Inventor)

1996-01-01

99

Phase plane based identification of fetal heart rate patterns  

PubMed Central

Using a phase plane analysis (PPA) of the spatial spread of trajectories of the fetal heart rate and its time-derivative we characterize the fetal heart rate patterns (fHRP) as defined by Nijhuis. For this purpose, we collect 22 fetal magnetocardiogram using a 151 SQUID system from 22 low-risk fetuses in gestational ages ranging from 30 to 37 weeks. Each study lasted for 30 minutes. After the attenuation of the maternal cardiac signals, we identify the R waves using an adaptive Hilbert transform approach and calculate the fetal heart rate. On these datasets, we apply the proposed approach and the traditionally used approaches such as standard deviation of the normal to normal intervals (SDNN) and root mean square of the successive difference (RMSSD). Heart rate patterns are scored by an expert using Nijhuis criteria and revealed A, B, and D patterns. A receiver operator characteristic (ROC) curve is used to assess the performance of the metric to differentiate the different patterns. Results showed that only PPA was able to differentiate all pairs of fHRP with high performance.

Vairavan, Srinivasan; Sriram, Bhargavi; Wilson, James D.; Preissl, Hubert; Eswaran, Hari

2012-01-01

100

Heart Rate Variability and Work-Load Measurement  

Microsoft Academic Search

Heart rate variability is a result of the superimposition of different sources of variation which are systemized. Three parameters are used to describe the phenomenon of heart rate variation. The range of variation of these parameters is discussed using examples from both laboratory and field investigations. Analyses demonstrate a correlation between heart rate and their variability. Discussion of of the

W. ROHMERT; W. LAURIG; U. PHILIPP; H. LUCZAK

1973-01-01

101

Model-based Heart rate prediction during Lokomat walking  

Microsoft Academic Search

We implemented a model for prediction of heart rate during Lokomat walking. Using this model, we can predict potential overstressing of the patient and adapt the physical load accordingly. Current models for treadmill based heart rate control neglect the fact that the interaction torques between Lokomat and human can have a significant effect on heart rate. Tests with five healthy

Alexander C. Koenig; Luca Somaini; Michael Pulfer; Thomas Holenstein; Ximena Omlin; Martin Wieser; Robert Riener

2009-01-01

102

INSTRUMENTAL CONDITIONING OF THE HEART RATE IN THE CURARIZED RAT  

Microsoft Academic Search

RATS, PREVIOUSLY TRAINED TO BAR PRESS FOR ELECTRICAL STIMULATION OF THE BRAIN (ESB), RECEIVED ESB ON A FIXED INTERVAL SCHEDULE FOR EITHER RELATIVELY FAST OR RELATIVELY SLOW HEART RATE LEVELS WHILE THEIR SKELETAL MUSCULATURE WAS COMPLETELY PARALYZED BY D-TUBOCURARINE CHLORIDE. 15 OF 19 SS, REWARDED FOR FAST HEART RATES, INCREASED THEIR HEART RATES DURING A TRAINING PERIOD, 15 OF 17

JAY A. TROWILL

1967-01-01

103

Heart rate biofeedback and cold pressor pain: Effects of expectancy  

Microsoft Academic Search

The study investigated the effects of expectancy on the reduction of cold pressor test pain using heart rate biofeedback training. Thirty-six male subjects were given an initial 45-sec cold pressor test, 25 heart rate decrease feedback training trials, and a final cold pressor test in which they were told to decrease their heart rate, but without the aid of feedback.

Kenneth L. Subotnik; David Shapiro

1984-01-01

104

Does physiologic gastroesophageal reflux affect heart rate or rhythm?  

PubMed

An acid-induced, cholinergic esophagocardiac reflex has been observed in humans. Decrements of heart rate can be induced by direct intraesophageal acid infusion. To ascertain whether this reflex occurs during physiologic reflux and whether stimulation of this reflex might precipitate dysrhythmias, a prospective study was performed. Twenty consecutive patients referred for 24-h ambulatory intraesophageal pH monitoring underwent simultaneous 24-h cardiac holter monitoring. Analyses were performed only on gastroesophageal reflux episodes which resulted in esophageal acidification to pH < 4 for 60 sec or more. Evaluable cardiac holter variables included premature ventricular contractions (PVCs), premature atrial contractions (PACs), tachycardia (heart rate, > 110/min), and bradycardia (heart rate, < 50/min). Measurements were made for 60 sec before and after onset of esophageal acidification. No relationship was noted between physiologic episodes of gastroesophageal reflux and PVCs (p = 0.29), PACs (p = 0.12), tachycardia (p = 0.33), or bradycardia (p = 0.78). No statistically significant correlations were noted between total 24-h acid exposure (minutes/24h) and mean heart rate (p = 0.07), number of PVCs (p = 0.41), and number of PACs (p = 0.39). Analyses of reflux episodes lasting more than 5 min with intraesophageal pH < 2 also failed to show changes in pulse rate (p = 0.22). Physiologic gastroesophageal reflux does not induce changes in heart rate or rhythm in humans. It is possible that esophagocardiac reflexes noted during intraesophageal acid infusion are related to lower pH values or to other factors such as osmolarity, temperature, or site-specific receptors. PMID:8284624

Wright, R A; McClave, S A; Petruska, J

1993-11-01

105

What's Normal? -- Temperature, Gender, and Heart Rate  

NSDL National Science Digital Library

This article, created by Allen L. Shoemaker of Calvin College, describes a dataset on body temperature, gender, and heart rate. The data is taken from a paper in the "Journal of the American Medical Association" that examined whether humans' true body temperature was 98.6 degrees. It addresses concepts like true means, confidence intervals, t-statistics, t-tests, the normal distribution, and regression. The author states that "it helps students to grasp concepts about true means, confidence intervals and t-statistics." This is a nice introduction into how statistics can be used in the medical field.

Shoemaker, Allen L.

2009-06-19

106

A Performance of the Heart  

ERIC Educational Resources Information Center

How the heart works is found in "A Framework for K-12 Science Education" and connects to Life Sciences Core and Component Ideas, From Molecules to Organisms: Structures and Processes (NRC 2012). By the end of grade 2, students should understand that all organisms have external parts, which they use in various ways to seek, find, and take…

Williams, Joan; McCauley, Joyce; Grumble, Melissa

2013-01-01

107

The relationship between resting heart rate variability and heart rate recovery  

Microsoft Academic Search

Objective  There is limited research available regarding a possible relationship between resting heart rate variability (HRV) and post-exercise\\u000a heart rate recovery (HRR). The aim of this study was to examine the relationship between resting HRV and HRR after maximal\\u000a exercise.\\u000a \\u000a \\u000a \\u000a Methods  Sixty-six college age men participated in this study. HRV was measured in a supine position before and for 30 min after a

Michael R. Esco; Michele S. Olson; Henry N. Williford; Daniel L. Blessing; David Shannon; Peter Grandjean

2010-01-01

108

Normal Ranges of Heart Rate Variability During Infancy and Childhood  

Microsoft Academic Search

.   Heart rate variability is a noninvasive index of the neural activity of the heart. The present study examined heart rate\\u000a variability indices in 210 infants and children aged 3 days to 14 years to obtain normal ranges for all age classes. Heart\\u000a rate variability was measured by calculating mean RR interval over the length of the analysis, mean RR

M. Massin; G. von Bernuth

1997-01-01

109

Heart rate recovery after exercise is related to the insulin resistance syndrome and heart rate variability in elderly men  

Microsoft Academic Search

Objective We investigated the associations between heart rate recovery after exercise (as a suggested measure of vagal activity), heart rate variability, and measurements of the insulin resistance syndrome. Material and Methods Seventy men aged 70 years were examined with a symptom-limited bicycle exercise test, a 24-hour heart rate variability test, and different measurements of different components of the insulin resistance

Lars Lind; Bertil Andrén

2002-01-01

110

Effect of Chronic Changes in Heart Rate on Congestive Heart Failure  

Microsoft Academic Search

BackgroundHeart rate can affect cardiac function, but the importance of rates lower than 100 paced beats per minute is unknown. We therefore sought to evaluate the impact of different heart rates on ejection fraction, 6-minute walk, and peak oxygen consumption (VO2) in heart failure patients.

Krishnamurti Rao; Michael L. Fisher; Shawn Robinson; Stephen Shorofsky; Stephen S. Gottlieb

2007-01-01

111

Model-based Heart rate prediction during Lokomat walking.  

PubMed

We implemented a model for prediction of heart rate during Lokomat walking. Using this model, we can predict potential overstressing of the patient and adapt the physical load accordingly. Current models for treadmill based heart rate control neglect the fact that the interaction torques between Lokomat and human can have a significant effect on heart rate. Tests with five healthy subjects lead to a model of sixth order with walking speed and power expenditure as inputs and heart rate prediction as output. Recordings with five different subjects were used for model validation. Future work includes model identification and predictive heart rate control with spinal cord injured and stroke patients. PMID:19963765

Koenig, Alexander C; Somaini, Luca; Pulfer, Michael; Holenstein, Thomas; Omlin, Ximena; Wieser, Martin; Riener, Robert

2009-01-01

112

Continuous positive airway pressure increases heart rate variability in heart failure patients with obstructive sleep apnoea  

Microsoft Academic Search

Patients with heart failure or OSA (obstructive sleep apnoea) have reduced HF-HRV (high- frequency heart rate variability), indicating reduced cardiac vagal modulation, a marker of poor prognosis. CPAP (continuous positive airway pressure) abolishes OSA in patients with heart failure, but effects on daytime HF-HRV have not been determined. We hypothesized that, in patients with heart failure, treatment of coexisting OSA

Kengo Usui; Yasuyuki Kaneko

2008-01-01

113

Adaptation of autonomic heart rate regulation in astronauts after spaceflight.  

PubMed

Background: Spaceflight causes changes in the cardiovascular control system. The aim of this study was to evaluate postflight recovery of linear and nonlinear neural markers of heart rate modulation, with a special focus on day-night variations. Material/Methods: Twenty-four-hour Holter ECG recordings were obtained in 8 astronauts participating in space missions aboard the International Space Station (ISS). Data recording was performed 1 month before launch, and 5 and 30 days after return to Earth from short- and long-term flights. Cardiovascular control was inferred from linear and nonlinear heart rate variability (HRV) parameters, separately during 2-hour day and 2-hour night recordings. Results: No remarkable differences were found in the postflight recovery between astronauts from short- and long-duration spaceflights. Five days after return to Earth, vagal modulation was significantly decreased compared to the preflight condition (day: p=0.001; night: p=0.019), while the sympathovagal balance was strongly increased, but only at night (p=0.017). A few nonlinear parameters were reduced early postflight compared to preflight values, but these were not always statistically significant. No significant differences remained after 30 days of postflight recovery. Conclusions: Our results show that 5 days after return from both short- and long-duration space missions, neural mechanisms of heart rate regulation are still disturbed. After 1 month, autonomic control of heart rate recovered almost completely. PMID:23291736

Vandeput, Steven; Widjaja, Devy; Aubert, Andre E; Van Huffel, Sabine

2013-01-01

114

A PC-aided optical foetal heart rate detection system.  

PubMed

Safe monitoring of foetal heart rate is a valuable tool for the healthy evolution and wellbeing of both foetus and mother. This paper presents a non-invasive optical technique that allows for foetal heart rate detection using a photovoltaic infrared (IR) detector placed on the mother's abdomen. The system presented here consists of a photoplethysmography (PPG) circuit, abdomen circuit and a personal computer equipped with MATLAB. A near IR beam having a wavelength of 880?nm is transmitted through the mother's abdomen and foetal tissue. The received abdominal signal that conveys information pertaining to the mother and foetal heart rate is sensed by a low noise photodetector. The PC receives the signal through the National Instrumentation Data Acquisition Card (NIDAQ). After synchronous detection of the abdominal and finger PPG signals, the designed MATLAB-based software saves, analyses and extracts information related to the foetal heart rate. Extraction is carried out using recursive least squares adaptive filtration. Measurements on eight pregnant women with gestational periods ranging from 35-39 weeks were performed using the proposed system and CTG. Results show a correlation coefficient of 0.978 and a correlation confidence interval between 88-99.6%. The t test results in a p value of 0.034, which is less than 0.05. Low power, low cost, high signal-to-noise ratio, reduction of ambient light effect and ease of use are the main characteristics of the proposed system. PMID:24195701

Oweis, Rami J; As'ad, Hala; Aldarawsheh, Amany; Al-Khdeirat, Rawan; Lwissy, Kaldoun

2014-01-01

115

Adaptation of autonomic heart rate regulation in astronauts after spaceflight  

PubMed Central

Background Spaceflight causes changes in the cardiovascular control system. The aim of this study was to evaluate postflight recovery of linear and nonlinear neural markers of heart rate modulation, with a special focus on day-night variations. Material/Methods Twenty-four-hour Holter ECG recordings were obtained in 8 astronauts participating in space missions aboard the International Space Station (ISS). Data recording was performed 1 month before launch, and 5 and 30 days after return to Earth from short- and long-term flights. Cardiovascular control was inferred from linear and nonlinear heart rate variability (HRV) parameters, separately during 2-hour day and 2-hour night recordings. Results No remarkable differences were found in the postflight recovery between astronauts from short- and long-duration spaceflights. Five days after return to Earth, vagal modulation was significantly decreased compared to the preflight condition (day: p=0.001; night: p=0.019), while the sympathovagal balance was strongly increased, but only at night (p=0.017). A few nonlinear parameters were reduced early postflight compared to preflight values, but these were not always statistically significant. No significant differences remained after 30 days of postflight recovery. Conclusions Our results show that 5 days after return from both short- and long-duration space missions, neural mechanisms of heart rate regulation are still disturbed. After 1 month, autonomic control of heart rate recovered almost completely.

Vandeput, Steven; Widjaja, Devy; Aubert, Andre E.; Van Huffel, Sabine

2013-01-01

116

Design and implementation of a heart rate meter  

Microsoft Academic Search

This paper describes the design and implementation of system to measure the heart frequency and rate based on a Doppler ultrasonic sensor, an analog filter and amplifier board, a frequency detecting circuit, an envelop detector and a microcontroller. The system is designed to measure the correct heart rate and give statistical information about the heart properly operation.

C. Garcia-Guendulain; J. C. Rosas-Caro; J. L. Garcia-Guendulain; C. G. Torres-Orozco; R. Salas-Cabrera

2010-01-01

117

Accuracy of detecting changes in auditory heart rate in a simulated operating room environment.  

PubMed

The threshold for the identification of changes in heart rate and the accuracy in estimating heart rate were compared between 20 anaesthetists and 20 non-anaesthetists in a simulated operating theatre, both with and without distraction tasks. Typical operating theatre distractions were simulated by requiring anaesthetists and non-anaesthetists to perform secondary tasks. There were no differences found between the groups in identification of heart rate changes. The distraction tasks reduced performance in both groups (to a greater extent in the anaesthetists group). A change of > 10 beats per minute was required for 80% of the changes to be detected. An upward heart rate change was more easily detected than a reduction. Anaesthetists were found to be marginally better at estimating the heart rate change from an auditory tone alone. However, the study did not confirm that anaesthetists have a superior ability to detect changes in heart rate than non-anaesthetists. PMID:18822093

Chou, E; Lim, J; Brant, R; Ford, S; Ansermino, J M

2008-11-01

118

Heart rate variability and sympathovagal balance: pharmacological validation  

PubMed Central

Rationale We validated heart rate (HR) and six time and six frequency domain measures of heart rate variability (HRV) as estimators of autonomic outflow in 44 young healthy male subjects. Gold standards for autonomic outflow were the Rosenblueth-Simeone factors m (sympathetic tone) and n (vagal tone), and the sympathovagal balance m·n, determined by two-stage complete autonomic blockade. Methods Rank correlations were computed between HR and the HRV measures obtained before autonomic blockade, and m, n and m·n. Also, the maximal mean performances (averaged sensitivity and specificity) for HR and HRV as discriminators between low and high values of m, n or m·n were computed. Results The spectral HRV measures showed less good correlations and performances than the time domain HRV measures. Correlations with sympathetic tone were all below 0.31. Respiratory sinus arrhythmia during 15 cycles/min metronome breathing was superior in estimating vagal tone and sympathovagal balance (correlations -0.71/-0.73; both performances 0.82), heart rate scored similarly for assessing the sympathovagal balance (correlation 0.71; performance 0.82). Conclusions It does not appear justified to evaluate HR or HRV in terms of sympathetic tone, vagal tone, or sympathovagal balance. HR and HRV are specifically weak in assessing sympathetic tone. Respiratory sinus arrhythmia during 15 cycles/min metronome breathing is superior in assessing vagal tone. Current HRV analysis techniques offer no advantages compared with HR in assessing the sympathovagal balance.

Bootsma, M.; Swenne, C.A.; Janssen, M.J.A.; Cats, V. Manger; Schalij, M.J.

2003-01-01

119

A Work-Performing Heart Preparation for Myocardial Performance Analysis in Murine Hearts  

Microsoft Academic Search

The mouse has become the animal of choice for genetic manipulations resulting in altered myocardial function, but assessment of cardiac function is extremely difficult due to the animal's size. This study was designed to establish a work-performing isolated mouse heart preparation to objectively investigate myocardial performance in murine hearts. Isolated work-performing cardiac functional studies were performed on a modified Langendorff

Hartmuth B. Bittner; Edward P. Chen; David S. Peterseim; Peter Van Trigt

1996-01-01

120

Study of Heart Rate and Heart Rate Variability during Rapid Decompression to 50,000 FT.  

National Technical Information Service (NTIS)

A previous study of the heart rate (HR) response to positive pressure breathing (PPB), anxiety and hypoxia during rapid decompression (RD) revealed a consistent pattern in the beat-to-beat or interbeat interval variability of HR, known in the literature a...

C. S. Chopp J. B. Bomar J. A. Dellinger

1994-01-01

121

Transfer of Heart Rate Feedback Training to Reduce Heart Rate Response to Laboratory Tasks  

Microsoft Academic Search

To examine whether transfer of heart rate (HR) feedback training to tasks not used during training could be improved by using multiple tasks during training, a modified multiple baseline across tasks, single subject design study was conducted using six high HR-reactive young adults. Participants received HR feedback training during the presentation of a videogame, and transfer of training was assessed

Jeffrey L. Goodie; Kevin T. Larkin

2006-01-01

122

Music structure determines heart rate variability of singers.  

PubMed

Choir singing is known to promote wellbeing. One reason for this may be that singing demands a slower than normal respiration, which may in turn affect heart activity. Coupling of heart rate variability (HRV) to respiration is called Respiratory sinus arrhythmia (RSA). This coupling has a subjective as well as a biologically soothing effect, and it is beneficial for cardiovascular function. RSA is seen to be more marked during slow-paced breathing and at lower respiration rates (0.1 Hz and below). In this study, we investigate how singing, which is a form of guided breathing, affects HRV and RSA. The study comprises a group of healthy 18 year olds of mixed gender. The subjects are asked to; (1) hum a single tone and breathe whenever they need to; (2) sing a hymn with free, unguided breathing; and (3) sing a slow mantra and breathe solely between phrases. Heart rate (HR) is measured continuously during the study. The study design makes it possible to compare above three levels of song structure. In a separate case study, we examine five individuals performing singing tasks (1-3). We collect data with more advanced equipment, simultaneously recording HR, respiration, skin conductance and finger temperature. We show how song structure, respiration and HR are connected. Unison singing of regular song structures makes the hearts of the singers accelerate and decelerate simultaneously. Implications concerning the effect on wellbeing and health are discussed as well as the question how this inner entrainment may affect perception and behavior. PMID:23847555

Vickhoff, Björn; Malmgren, Helge; Aström, Rickard; Nyberg, Gunnar; Ekström, Seth-Reino; Engwall, Mathias; Snygg, Johan; Nilsson, Michael; Jörnsten, Rebecka

2013-01-01

123

Music structure determines heart rate variability of singers  

PubMed Central

Choir singing is known to promote wellbeing. One reason for this may be that singing demands a slower than normal respiration, which may in turn affect heart activity. Coupling of heart rate variability (HRV) to respiration is called Respiratory sinus arrhythmia (RSA). This coupling has a subjective as well as a biologically soothing effect, and it is beneficial for cardiovascular function. RSA is seen to be more marked during slow-paced breathing and at lower respiration rates (0.1 Hz and below). In this study, we investigate how singing, which is a form of guided breathing, affects HRV and RSA. The study comprises a group of healthy 18 year olds of mixed gender. The subjects are asked to; (1) hum a single tone and breathe whenever they need to; (2) sing a hymn with free, unguided breathing; and (3) sing a slow mantra and breathe solely between phrases. Heart rate (HR) is measured continuously during the study. The study design makes it possible to compare above three levels of song structure. In a separate case study, we examine five individuals performing singing tasks (1–3). We collect data with more advanced equipment, simultaneously recording HR, respiration, skin conductance and finger temperature. We show how song structure, respiration and HR are connected. Unison singing of regular song structures makes the hearts of the singers accelerate and decelerate simultaneously. Implications concerning the effect on wellbeing and health are discussed as well as the question how this inner entrainment may affect perception and behavior.

Vickhoff, Bjorn; Malmgren, Helge; Astrom, Rickard; Nyberg, Gunnar; Ekstrom, Seth-Reino; Engwall, Mathias; Snygg, Johan; Nilsson, Michael; Jornsten, Rebecka

2013-01-01

124

Heart Rate Variability and Sustained Attention in ADHD Children  

Microsoft Academic Search

The major goal of the current study was to investigate the association between continuous performance tests (CPTs) and the heart rate variability (HRV) of attention deficit hyperactivity disorder (ADHD) children. The HRV, specifically the 0.10-Hz component, may be considered to be a psychophysiological index of effort allocation (motivation): The less effort the subject allocates, the greater the 0.10-Hz component. Results

Norbert Börger; Jaap van Der Meere; Arjen Ronner; Ed Alberts; Reint Geuze; Hans Bogte

1999-01-01

125

Variability in heart rate recovery measurements over 1 year in healthy, middle-aged adults.  

PubMed

This study assessed the longer-term (12-month) variability in post-exercise heart rate recovery following a submaximal exercise test. Longitudinal data was analysed for 97 healthy middle-aged adults (74 male, 23 female) from 2 occasions, 12 months apart. Participants were retrospectively selected if they had stable physical activity habits, submaximal treadmill fitness and anthropometric measurements between the 2 assessment visits. A submaximal Bruce treadmill test was performed to at least 85% age-predicted maximum heart rate. Absolute heart rate and ? heart rate recovery (change from peak exercise heart rate) were recorded for 1 and 2 min post-exercise in an immediate supine position. Heart rate recovery at both time-points was shown to be reliable with intra-class correlation coefficient values ? 0.714. Absolute heart rate 1-min post-exercise showed the strongest agreement between repeat tests (r = 0.867, P < 0.001). Lower coefficient of variation (??10.2%) and narrower limits of agreement were found for actual heart rate values rather than ? heart rate recovery, and for 1-min rather than 2-min post-exercise recovery time points. Log-transformed values generated better variability with acceptable coefficient of variation for all measures (2.2-10%). Overall, 1 min post-exercise heart rate recovery data had least variability over the 12-month period in apparently healthy middle-aged adults. PMID:23868686

Mellis, M G; Ingle, L; Carroll, S

2014-02-01

126

Pre-exercise food and heart rate during submaximal exercise  

Microsoft Academic Search

The heart rates of 20 movement studies students were measured during multi-stage cycle ergometer tests. The tests were repeated on five occasions following the ingestion of different pre-exercise meals and the results compared. A glucose solution taken three hours prior to the exercise (G3) resulted in the lowest heart rates at each work rate. The highest heart rates at each

S R Bird; S Hay

1987-01-01

127

Ordinal pattern statistics for the assessment of heart rate variability  

NASA Astrophysics Data System (ADS)

The recognition of all main features of a healthy heart rhythm (the so-called sinus rhythm) is still one of the biggest challenges in contemporary cardiology. Recently the interesting physiological phenomenon of heart rate asymmetry has been observed. This phenomenon is related to unbalanced contributions of heart rate decelerations and accelerations to heart rate variability. In this paper we apply methods based on the concept of ordinal pattern to the analysis of electrocardiograms (inter-peak intervals) of healthy subjects in the supine position. This way we observe new regularities of the heart rhythm related to the distribution of ordinal patterns of lengths 3 and 4.

Graff, G.; Graff, B.; Kaczkowska, A.; Makowiec, D.; Amigó, J. M.; Piskorski, J.; Narkiewicz, K.; Guzik, P.

2013-06-01

128

Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indices  

Microsoft Academic Search

This study aimed to investigate the effect of cold and thermoneutral water immersion on post-exercise parasympathetic reactivation, inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Twelve men performed, on three separate occasions, an intermittent exercise bout (all-out 30-s Wingate test, 5min seated recovery, followed by 5min of submaximal running exercise), randomly followed by 5min of passive

Hani Al Haddad; Paul B. Laursen; Didier Chollet; Frédéric Lemaitre; Saïd Ahmaidi; Martin Buchheit

2010-01-01

129

gHRV: Heart rate variability analysis made easy.  

PubMed

In this paper, the gHRV software tool is presented. It is a simple, free and portable tool developed in python for analysing heart rate variability. It includes a graphical user interface and it can import files in multiple formats, analyse time intervals in the signal, test statistical significance and export the results. This paper also contains, as an example of use, a clinical analysis performed with the gHRV tool, namely to determine whether the heart rate variability indexes change across different stages of sleep. Results from tests completed by researchers who have tried gHRV are also explained: in general the application was positively valued and results reflect a high level of satisfaction. gHRV is in continuous development and new versions will include suggestions made by testers. PMID:24854108

Rodríguez-Liñares, L; Lado, M J; Vila, X A; Méndez, A J; Cuesta, P

2014-08-01

130

Controlling the emotional heart: heart rate biofeedback improves cardiac control during emotional reactions.  

PubMed

When regulating negative emotional reactions, one goal is to reduce physiological reactions. However, not all regulation strategies succeed in doing that. We tested whether heart rate biofeedback helped participants reduce physiological reactions in response to negative and neutral pictures. When viewing neutral pictures, participants could regulate their heart rate whether the heart rate feedback was real or not. In contrast, when viewing negative pictures, participants could regulate heart rate only when feedback was real. Ratings of task success paralleled heart rate. Participants' general level of anxiety, emotion awareness, or cognitive emotion regulation strategies did not influence the results. Our findings show that accurate online heart rate biofeedback provides an efficient way to down-regulate autonomic physiological reactions when encountering negative stimuli. PMID:24373886

Peira, Nathalie; Fredrikson, Mats; Pourtois, Gilles

2014-03-01

131

Heart Rate and Risk of Cancer Death in Healthy Men  

Microsoft Academic Search

BackgroundData from several previous studies examining heart-rate and cardiovascular risk have hinted at a possible relationship between heart-rate and non-cardiac mortality. We thus systematically examined the predictive value of heart-rate variables on the subsequent risk of death from cancer.MethodsIn the Paris Prospective Study I, 6101 asymptomatic French working men aged 42 to 53 years, free of clinically detectable cardiovascular disease

Xavier Jouven; Sylvie Escolano; David Celermajer; Jean-Philippe Empana; Annie Bingham; Olivier Hermine; Michel Desnos; Marie-Cécile Perier; Eloi Marijon; Pierre Ducimetière

2011-01-01

132

Heart rate variability and heart rate turbulence in mild-to-moderate aortic stenosis  

Microsoft Academic Search

Aims To study heart rate (HR) variability and HR turbulence parameters in mild-to-moderate aortic stenosis (AS) and to disclose whether any relationship exists between these parameters and echocardio- graphic findings. Methods and results Forty-three asymptomatic patients with mild-to-moderate AS (AS group) were studied. Echocardiographic parameters and HR variability and HR turbulence indices obtained over 24 Holter ECG recordings were compared

Murat Ozdemir; Sinan Altan Kocaman; Atiye Cengel

133

Spectral analysis of heart rate variability in the sepsis syndrome  

Microsoft Academic Search

Sympathetic and parasympathetic activity was evaluated on 39 occasions in 17 patients with the sepsis syndrome, by measurement of the variation in resting heart rate using frequency spectrum analysis. Heart rate was recorded by electrocardiography and respiratory rate by impedance plethysmography. The sepsis syndrome was established on the basis of established clinical and physiological criteria. Subjects were studied, whenever possible,

Christopher S. Garrard; Dimitrios A. Kontoyannis; Massimo Piepoli

1993-01-01

134

Detection of changes in the fractal scaling of heart rate and speed in a marathon race  

Microsoft Academic Search

The aim of this study was to detect changes in the fractal scaling behavior of heart rate and speed fluctuations when the average runner’s speed decreased with fatigue. Scaling analysis in heart rate (HR) and speed (S) dynamics of marathon runners was performed using the detrended fluctuation analysis (DFA) and the wavelet based structure function. We considered both: the short-range

Véronique L. Billat; Laurence Mille-Hamard; Yves Meyer; Eva Wesfreid

2009-01-01

135

Effects of ?-blockade with bisoprolol on heart rate variability in advanced heart failure: Analysis of scatterplots of RR intervals at selected heart rates  

Microsoft Academic Search

The effect of ?-blockade on heart-rate variability was assessed at different heart rates in 52 patients with heart failure included in the randomized, placebo-controlled, Cardiac Insufficiency Bisoprolol Study (CIBIS). Scatterplots of R-R intervals display beat-to-beat variability by plotting each R-R interval against the preceding interval. Scatterplot dispersion at different R-R intervals provides a measure of beat-to-beat heart-rate variability at different

Xavier Copie; Françoise Pousset; Philippe Lechat; Patrice Jaillon; Louis Guize; Jean-Yves Le Heuzey

1996-01-01

136

Predictors of abnormal heart rate recovery in patients with heart failure reduced and preserved ejection fraction.  

PubMed

BACKGROUND: Heart rate recovery (HRR) is becoming an important prognostic maker in heart failure (HF), but very little is known about the underlying mechanisms responsible for its clinical efficacy. Therefore, we examined echocardiographic and exercise (submaximal and maximal) characteristics to gain a better appreciation of HRR and factors responsible for the development of abnormal HRR in patients with both heart failure reduced ejection fraction (HFrEF) and heart failure preserved ejection fraction (HFpEF). METHODS: Cardiopulmonary exercise testing (CPX), a 6-minute walk test (6MWT), and resting 2D echocardiography were randomly performed in 240 HF patients (200 HFrEF, 40 HFpEF) after which HRR was measured. HRR was defined as the difference between heart rate at peak exercise and 1?minute following test termination. RESULTS: Bivariate correlation analyses found significant relationships among most CPX and 6MWT measurements with the highest correlations between 6MWT HRR and 6MWT peak HR (r?=?0.65; p?performance in patients with HFrEF and HFpEF. PMID:23335654

Cahalin, Lawrence P; Arena, Ross; Labate, Valentina; Bandera, Francesco; Guazzi, Marco

2013-03-11

137

Heart rate variability in patients with Sjögren's syndrome.  

PubMed

Heart rate variability (HRV) gives information about sympathetic parasympathetic autonomic balance. Our purpose was to determine whether HRV is abnormal in patients with Sjögren's syndrome. In 16 patients with Sjögren's syndrome and 30 matched controls, a short time analysis of HRV was performed for both the frequency and the time domain. In the time domain, patients tended to display a slower heart rate, greater R-R variability and higher standard deviation of the mean (SDNN) than did healthy subjects, but the differences were not statistically significant. In the frequency domain the spectral measures of HRV showed a slight reduction of LF and an increase of HF; as a result, the ratio between high and low frequencies, representative of sympathovagal modulation, was significantly reduced. Our data suggest an increase in the parasympathetic control of heart rate in patients with Sjögren's syndrome. This predominance in vagal tone could exert a protective and antiarrhythmic role in patients with primary Sjögren's syndrome, and may be relevant with reference to the lower incidence of sudden death in this disorder compared to other major autoimmune diseases. PMID:11147760

Tumiati, B; Perazzoli, F; Negro, A; Pantaleoni, M; Regolisti, G

2000-01-01

138

Heart rate, ischaemic heart disease, and sudden cardiac death in middle-aged British men  

Microsoft Academic Search

OBJECTIVE--To examine the relation between resting heart rate and new major ischaemic heart disease events in middle aged men with and without pre-existing ischaemic heart disease. DESIGN--Prospective study of a cohort of men with eight years follow up for cardiovascular morbidity and mortality for all men. SETTING--General practices in 24 British towns (the British Regional Heart study). SUBJECTS--7735 men aged

A G Shaper; G Wannamethee; P W Macfarlane; M Walker

1993-01-01

139

Highly comparative fetal heart rate analysis.  

PubMed

A database of fetal heart rate (FHR) time series measured from 7 221 patients during labor is analyzed with the aim of learning the types of features of these recordings that are informative of low cord pH. Our 'highly comparative' analysis involves extracting over 9 000 time-series analysis features from each FHR time series, including measures of autocorrelation, entropy, distribution, and various model fits. This diverse collection of features was developed in previous work [1]. We describe five features that most accurately classify a balanced training set of 59 'low pH' and 59 'normal pH' FHR recordings. We then describe five of the features with the strongest linear correlation to cord pH across the full dataset of FHR time series. The features identified in this work may be used as part of a system for guiding intervention during labor in future. This work successfully demonstrates the utility of comparing across a large, interdisciplinary literature on time-series analysis to automatically contribute new scientific results for specific biomedical signal processing challenges. PMID:23366590

Fulcher, B D; Georgieva, A E; Redman, C W G; Jones, N S

2012-01-01

140

Relative Risk Forests for Exercise Heart Rate Recovery as a Predictor of Mortality  

Microsoft Academic Search

Recent studies have confirmed heart rate fall after treadmill exercise testing, or heart rate recovery, as a powerful predictor of mortality from heart disease. Heart rate recovery depends on central reactivation of vagal tone and decreased vagal activity is a risk factor for death. If heart rate recovery is defined as the fall in heart rate after 1 minute following

Hemant Ishwaran; Eugene H. Blackstone; Claire E. Pothier; Michael S. Lauer

2004-01-01

141

Adaptive Multiscale Complexity Analysis of Fetal Heart Rate  

Microsoft Academic Search

Per partum fetal asphyxia is a major cause of neona- tal morbidity and mortality. Fetal heart rate monitoring plays an important role in early detection of acidosis, an indicator for as- phyxia. This problem is addressed in this paper by introducing a novel complexity analysis of fetal heart rate data, based on pro- ducing a collection of piecewise linear approximations

H. Helgason; P. Abry; P. Gaucherand; Cl. Gharib; M. Doret

2011-01-01

142

Heart Rate Recovery During a College Basketball Game.  

National Technical Information Service (NTIS)

It has been established by several investigators that heart rate is a good indicator of the energy expenditure for a given work task. Heart rate has also been shown to give quicker response to emotional involvement than do other measures of physiological ...

J. D. Ramsey M. M. Ayoub R. A. Dudek H. S. Edgar

1970-01-01

143

Behavioural correlation of heart rate changes in family dogs  

Microsoft Academic Search

Fourteen dogs (7 males and 7 females) were tested for their heart rate (HR) and heart rate variability (HRV) responses in different activities and environmental challenges while their movement was controlled. First, we wanted to compare the dogs’ cardiac responses in different body positions (lying, sitting and standing) and during slow walking to reveal their possible influence on HR and

Katalin Maros; Antal Dóka; Ádám Miklósi

2008-01-01

144

Heart rate variability in depressive and anxiety disorders  

Microsoft Academic Search

Loss of normal autonomic nervous system control of heart rate and rhythm is an important risk factor for adverse cardiovascular events. After myocardial infarction, reduction in beat-to-beat heart rate variability, a measure of cardiac autonomic innervation by the brain, is a strong predictor of death. With loss of vagal innervation, as is noted in patients with severe neuropathy and in

Jack M. Gorman; Richard P. Sloan

2000-01-01

145

Heart rate variability associated with particulate air pollution  

Microsoft Academic Search

Background: Epidemiologic studies have linked fine particulate air pollution with cardiopulmonary mortality, yet underlying biologic mechanisms remain unknown. Changes in heart rate variability (HRV) may reflect changes in cardiac autonomic function and risk of sudden cardiac death. This study evaluated changes in mean heart rate and HRV in human beings associated with changes in exposure to particulate air pollution. Methods:

C. Arden Pope; Richard L. Verrier; Eric G. Lovett; Andrew C. Larson; Mark E. Raizenne; Richard E. Kanner; Joel Schwartz; G. Martin Villegas; Diane R. Gold; Douglas W. Dockery

1999-01-01

146

Device for long term measurement of heart rate  

Microsoft Academic Search

In this contribution, a device for long term measurement of heart rate is described. The device is created based on development kit STM32-Primer2. Heart rate frequency is calculated from selected electrocardiograph lead from the external module. The device allows simultaneous recoding of acceleration which makes is appropriate for physical activity detection of the test subject. The recorded data is saved

Jakub Parak; Jan Dvorak; Jan Havlik

2011-01-01

147

Operant conditioning of changes in heart rate in curarized rats  

Microsoft Academic Search

Reinforced 1 group (N = 6) of curarized Sprague-Dawley male rats for heart-rate increases and another group (N = 6) for heart-rate decreases by electrical stimulation of the medial forebrain bundle. All Ss were run for 4 sessions each of which consisted of an adaptation, conditioning, and extinction phase. During the conditioning phase of each session a feedback stimulus was

David Hothersall; Jasper Brener

1969-01-01

148

Quantification of fetal heart rate regularity using symbolic dynamics  

Microsoft Academic Search

Fetal heart rate complexity was examined on the basis of RR interval time series obtained in the second and third trimester of pregnancy. In each fetal RR interval time series, short term beat-to-beat heart rate changes were coded in 8 bit binary sequences. Redundancies of the 28 different binary patterns were reduced by two different procedures. The complexity of these

P. van Leeuwen; D. Cysarz; S. Lange; D. Geue; D. Groenemeyer

2007-01-01

149

Heart rate-based lactate minimum test: a reproducible method  

Microsoft Academic Search

OBJECTIVE: To find the individual intensity for aerobic endurance training, the lactate minimum test (LMT) seems to be a promising method. LMTs described in the literature consist of speed or work rate-based protocols, but for training prescription in daily practice mostly heart rate is used. The aim of the present study was to investigate the reproducibility of a new heart

M. Strupler; G Mueller; C. Perret

2009-01-01

150

Retarding Effect of Lowered Heart Rate on Coronary Atherosclerosis  

Microsoft Academic Search

The role of heart rate in the development of coronary atherosclerosis was assessed in adult male cynomolgus monkeys (Macaca fascicularis). Heart rate was lowered in six animals by surgical ablation of the sinoatrial node. A sham procedure, which included all of the surgical steps except for sinoatrial node ablation, was carried out in eight animals. All of the monkeys were

Polly A. Beere; Seymour Glagov; Christopher K. Zarins

1984-01-01

151

Effect of Age and Other Factors on Maximal Heart Rate.  

ERIC Educational Resources Information Center

To reduce confusion regarding reported effects of age on maximal exercise heart rate, a comprehensive review of the relevant English literature was conducted. Data on maximal heart rate after exercising with a bicycle, a treadmill, and after swimming were analyzed with regard to physical fitness and to age, sex, and racial differences. (Authors/PP)

Londeree, Ben R.; Moeschberger, Melvin L.

1982-01-01

152

Heart rate control by the computerized infusion of isoproterenol  

Microsoft Academic Search

The authors developed a computerized system for the controlled acceleration of heart rate. Ten cannulated rats were connected to a monitoring system that sampled the ECG and arterial blood pressure. Isoproterenol was delivered via a computer controlled infusion pump that the authors have developed. A control software, based on a modified proportional integral controller, sensed the heart rate and stabilized

R. Leor; B. Z. Bobrovsky; S. Eliash; E. Kaplinsky

1997-01-01

153

Skinfold thickness is related to cardiovascular autonomic control as assessed by heart rate variability and heart rate recovery.  

PubMed

The purpose of this study was to determine if heart rate recovery (HRR) and heart rate variability (HRV) are related to maximal aerobic fitness and selected body composition measurements. Fifty men (age = 21.9 ± 3.0 years, height = 180.8 ± 7.2 cm, weight = 80.4 ± 9.1 kg, volunteered to participate in this study. For each subject, body mass index (BMI), waist circumference (WC), and the sum of skinfolds across the chest, abdomen, and thigh regions (SUMSF) were recorded. Heart rate variability (HRV) was assessed during a 5-minute period while the subjects rested in a supine position. The following frequency domain parameters of HRV were recorded: normalized high-frequency power (HFnu), and low-frequency to high-frequency power ratio (LF:HF). To determine maximal aerobic fitness (i.e., VO2max), each subject performed a maximal graded exercise test on a treadmill. Heart rate recovery was recorded 1 (HRR1) and 2 (HRR2) minutes during a cool-down period. Mean VO2max and BMI for all the subjects were 49.5 ± 7.5 ml·kg(-1)·min(-1) and 24.7 ± 2.2 kg·m(-2), respectively. Although VO2max, WC, and SUMSF was each significantly correlated to HRR and HRV, only SUMSF had a significant independent correlation to HRR1, HRR2, HFnu, LF:HF (p < 0.01). The results of the regression procedure showed that SUMSF accounted for the greatest variance in HRR1, HRR2, HFnu, and LF:HF (p < 0.01). The results of this study suggest that cardiovascular autonomic modulation is significantly related to maximal aerobic fitness and body composition. However, SUMSF appears to have the strongest independent relationship with HRR and HRV, compared to other body composition parameters and VO2max. PMID:21691230

Esco, Michael R; Williford, Henry N; Olson, Michele S

2011-08-01

154

Effects of Vibration and G-Loading on Heart Rate, Breathing Rate, and Response Time  

NASA Technical Reports Server (NTRS)

Aerospace and applied environments commonly expose pilots and astronauts to G-loading and vibration, alone and in combination, with well-known sensorimotor (Cohen, 1970) and performance consequences (Adelstein et al., 2008). Physiological variables such as heart rate (HR) and breathing rate (BR) have been shown to increase with G-loading (Yajima et al., 1994) and vibration (e.g. Guignard, 1965, 1985) alone. To examine the effects of G-loading and vibration, alone and in combination, we measured heart rate and breathing rate under aerospace-relevant conditions (G-loads of 1 Gx and 3.8 Gx; vibration of 0.5 gx at 8, 12, and 16 Hz).

Godinez, Angelica; Ayzenberg, Ruthie; Liston, Dorian B.; Stone, Leland S.

2013-01-01

155

[Heart rate measurement algorithm based on artificial intelligence].  

PubMed

Based on the heart rate measurement method using time-lapse image of human cheek, this paper proposes a novel measurement algorithm based on Artificial Intelligence. The algorithm combining with fuzzy logic theory acquires the heart beat point by using the defined fuzzy membership function of each sampled point. As a result, it calculates the heart rate by counting the heart beat points in a certain time period. Experiment shows said algorithm satisfies in operability, accuracy and robustness, which leads to constant practical value. PMID:20391917

Chengxian, Cai; Wei, Wang

2010-01-01

156

Effect of early bereavement on heart rate and heart rate variability.  

PubMed

Early bereavement is associated with increased cardiovascular events. The mechanism, however, has not been well studied. We assessed whether bereavement is associated with an increased heart rate (HR) and decreased heart rate variability that might contribute to increased cardiovascular risk. A total of 78 bereaved spouses and parents (55 women and 23 men; aged 34 to 87 years, mean 65) were studied with 24-hour Holter monitoring within 2 weeks of bereavement (acute) and at 6 months. Their findings were compared to those from a nonbereaved reference group (52 women and 27 men) aged 33 to 91 years (mean 63.6). All participants were in sinus rhythm. We assessed the mean HR, atrial and ventricular arrhythmias, and both time and frequency domain heart rate variability measures. Acute bereavement was associated with increased 24-hour HR (mean ± SE, 75.1 ± 1.1 vs 70.7 ± 1.0; p = 0.004) and reduced heart rate variability, as indicated by lower standard deviation of the NN intervals index (median 45.4 vs 49.9, p = 0.017), total power (7.78 ± 0.10 vs 8.02 ± 0.09, p = 0.03), very low frequency (7.23 ± 0.09 vs 7.44, p = 0.046) and low frequency (5.76 ± 0.12 vs 6.16 ± 0.09, p = 0.01). At 6 months, the bereaved had a significantly lower HR (p = 0.001) and increased standard deviation of the NN intervals index (p = 0.02), square root of the mean square of differences of successive intervals (p = 0.045), number of interval differences of successive NN intervals >50 ms divided by the number of NN intervals (p = 0.039), low-frequency power (p = 0.02), and high frequency (p = 0.002) compared to the initial acute levels. In conclusion, the present study, the first to report 24-hour HR monitoring in the early weeks of bereavement, has demonstrated increased HR and altered autonomic function that might contribute to the increased cardiovascular events in early bereavement. PMID:22853984

Buckley, Thomas; Stannard, Angela; Bartrop, Roger; McKinley, Sharon; Ward, Christopher; Mihailidou, Anastasia Susie; Morel-Kopp, Marie-Christie; Spinaze, Monica; Tofler, Geoffrey

2012-11-01

157

Relation of heart rate recovery to heart rate variability in persons with paraplegia  

Microsoft Academic Search

Purpose  Heart rate recovery (HRR) after treadmill exercise testing is an index of cardiac autonomic activity in non-disabled persons,\\u000a but it is unknown if this is also the case in individuals with spinal cord injury (SCI). We investigated the relationship\\u000a between HRR after maximal arm exercise testing and resting autonomic activity in persons with paraplegia.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A total of 17 (male n = 9,

Sae Young Jae; Kevin S. Heffernan; Miyoung Lee; Bo Fernhall

2011-01-01

158

Respiratory modulation and baroreflex control of heart rate in space  

NASA Astrophysics Data System (ADS)

During everyday life, gravity constantly stresses the human circulation by diminishing venous return in the upright position. This induces baroreflex-mediated cardiovascular adjustments that are aimed to prevent the blood pressure from falling. In weightlessness, gravitational pressure gradients do not arise in the circulation so that baroreflex function remains chronically unchallenged. This may contribute to the development of post spaceflight orthostatic intolerance. The purpose of this study was to evaluate respiratory modulation and baroreflex control of heart rate after a week of weightlessness in space. We tested the hypothesis that cardiovascular control in space will be similar to the baseline supine condition on Earth. We studied nine male cosmonauts during seven different space missions aboard the ISS (age 40 - 52 yrs, height 1.69 - 1.85 m, weight 67 - 90 kg). Data collection was performed between 30 and 45 days before launch in the standing and supine positions, and after 8 days in space. Cosmonauts were carefully trained to perform in-flight data collection by themselves. They were instructed to pace their breathing to a fixed rate of 12 breaths per minute (0.2 Hz) for a total duration of 3 minutes. The electrocardiogram and beat-by-beat finger arterial blood pressure were recorded at 1-kHz sample rate. Respiratory rate was evaluated using an abdominal pressure sensor. We used power spectral analysis to calculate respiratory sinus arrhythmia (RSA) as well as the low-frequency (0.04 - 0.15 Hz) powers of spontaneous oscillations in heart rate and systolic blood pressure. Baroreflex sensitivity (BRS) was estimated in the time domain using cross-correlation analysis. As expected, there was a rise in heart rate upon assuming the standing position before space- flight (59 ± 6 to 79 ± 11 beats per min; p ¡ 0.001). This was accompanied by an increase in mean arterial blood pressure (84 ± 6 to 93 ± 6 mmHg; p ¡ 0.001). Standing up further induced a marked increase in the low-frequency powers of systolic blood pressure oscillations (8 ± 7 to 17 ± 11 mmHg2; p = 0.018), whereas those in heart rate remained unchanged (445 ± 512 to 621 ± 799 ms2; p = 0.315). Alternatively, there was a reduction in RSA from 546 ± 167 ms2 to 158 ± 298 ms2 and in spontaneous BRS from 14 ± 5 ms/mmHg to 6 ± 2 ms/mmHg upon changing from supine to standing (both p ¡ 0.001). After a week of weightlessness in space, heart rate (61 ± 8 beats per min) and mean blood pressure (83 ± 6 mmHg) returned to the pre-flight supine values. This was also true for the low-frequency powers of systolic blood pressure (7 ± 4 mmHg2) and of heart rate (741 ± 716 ms2), as well as for RSA (465 ± 269 ms2) and spontaneous BRS (14 ± 4 ms/mmHg). It is concluded that cardiovascular control after one week in space corresponds to the pre-flight supine condition. This is characterized by a chronically increased vagal-cardiac outflow and suppressed sympathetic vasomotor modulation compared with the standing position on Earth. This kind of chronic baroreflex unloading is likely to contribute to post-spaceflight functional impairment of orthostatic blood pressure control.

Verheyden, Bart; Couckuyt, Kurt; Liu, Jiexin; Aubert, Andre

159

Heart rate and heart rate variability during a novel object test and a handling test in young horses  

Microsoft Academic Search

Forty-one Dutch Warmblood immature horses were used in a study to quantify temperamental traits on the basis of heart rate (HR) and heart rate variability (HRV) measures. Half of the horses received additional training from the age of 5 months onwards; the other half did not. Horses were tested at 9, 10, 21 and 22 months of age in a

E. K. Visser; C. G. van Reenen; M. B. H. Schilder; J. H. Knaap; A. Barneveld; H. J. Blokhuis

2002-01-01

160

Learning by Heart: Students Use Heart Rate Patterns To Identify Nervous System Imbalances.  

ERIC Educational Resources Information Center

Introduces a science unit on heart rate variability (HVR) patterns. Uses spectral analysis to determine the effects of environmental stimulants such as music and emotional stress on heart rate. Observes relaxation techniques and their effects on the autonomous nervous system. (Contains 12 references.) (YDS)

Ackerly, Spafford C.

2001-01-01

161

The effect of heart rate on the heart rate variability response to autonomic interventions.  

PubMed

Heart rate variability (HRV), the beat-to-beat variation in either heart rate (HR) or heart period (R-R interval), has become a popular clinical and investigational tool to quantify cardiac autonomic regulation. However, it is not widely appreciated that, due to the inverse curvilinear relationship between HR and R-R interval, HR per se can profoundly influence HRV. It is, therefore, critical to correct HRV for the prevailing HR particularly, as HR changes in response to autonomic neural activation or inhibition. The present study evaluated the effects of HR on the HRV response to autonomic interventions that either increased (submaximal exercise, n = 25 or baroreceptor reflex activation, n = 20) or reduced (pharmacological blockade: ?-adrenergic receptor, muscarinic receptor antagonists alone and in combination, n = 25, or bilateral cervical vagotomy, n = 9) autonomic neural activity in a canine model. Both total (RR interval standard deviation, RRSD) and the high frequency (HF) variability (HF, 0.24-1.04 Hz) were determined before and in response to an autonomic intervention. All interventions that reduced or abolished cardiac parasympathetic regulation provoked large reductions in HRV even after HR correction [division by mean RRsec or (mean RRsec)(2) for RRSD and HF, respectively] while interventions that reduced HR yielded mixed results. ?-adrenergic receptor blockade reduced HRV (RRSD but not HF) while both RRSD and HF increased in response to increases in arterial blood (baroreceptor reflex activation) even after HR correction. These data suggest that the physiological basis for HRV is revealed after correction for prevailing HR and, further, that cardiac parasympathetic activity is responsible for a major portion of the HRV in the dog. PMID:23986716

Billman, George E

2013-01-01

162

Age differences in heart rate patterns during concentration in a precision sport: implications for attentional functioning.  

PubMed

Highly skilled young (M = 29.5 years) and older (M = 50.0 years) miniature golf players were observed in relaxed training and high-arousal competition rounds. Motor performance (number of shots), subjective ratings of anxiety, and heart rate were registered. Results showed a similar increase of arousal from training to competition for both age groups. However, the older group deteriorated in motor performance from training to competition, whereas the younger group played equally well on both occasions. Results from continuous measurement of heart rate indicated a deceleration during the concentration phases among the younger players, and the magnitude of deceleration increased from training to competition. In contrast, heart rate accelerated during training among the older players, the magnitude of the heart rate change decreasing from training to competition. This evidence suggests that the deterioration in motor performance observed in older players in stressful competitive activity may be due to age-related changes in attentional functioning. PMID:2715589

Molander, B; Bäckman, L

1989-05-01

163

Approximate minimum bias multichannel spectral estimation for heart rate variability  

Microsoft Academic Search

Spectral decomposition of variations in heart rate permits noninvasive measurement of autonomic nervous activity in humans\\u000a and animals. Autonomic metrics based on spectral analysis are useful in monitoring clinical conditions such as diabetic neuropathy\\u000a and reinnervation in heart transplant patients. A persistent problem in deriving such autonomic measures is the prerequisite\\u000a of an accurate and unbiased power spectrum of heart

Eric G. Lovett; Joel B. Myklebust

1997-01-01

164

Heart rate and heart rate variability modification in chronic insomnia patients.  

PubMed

Chronic insomnia is highly prevalent in the general population, provoking personal distress and increased risk for psychiatric and medical disorders. Autonomic hyper-arousal could be a pathogenic mechanism of chronic primary insomnia. The aim of this study was to investigate autonomic activity in patients with chronic primary insomnia by means of heart rate variability (HRV) analysis. Eighty-five consecutive patients affected by chronic primary insomnia were enrolled (38 men and 47 women; mean age: 53.2 ± 13.6). Patients were compared with a control group composed of 55 healthy participants matched for age and gender (23 men and 32 women; mean age: 54.2 ± 13.9). Patients underwent an insomnia study protocol that included subjective sleep evaluation, psychometric measures, and home-based polysomnography with evaluation of HRV in wake before sleep, in all sleep stages, and in wake after final awakening. Patients showed modifications of heart rate and HRV parameters, consistent with increased sympathetic activity, while awake before sleep and during Stage-2 non-REM sleep. No significant differences between insomniacs and controls could be detected during slow-wave sleep, REM sleep, and post-sleep wake. These results are consistent with the hypothesis that autonomic hyper-arousal is a major pathogenic mechanism in primary insomnia, and confirm that this condition is associated with an increased cardiovascular risk. PMID:24128278

Farina, Benedetto; Dittoni, Serena; Colicchio, Salvatore; Testani, Elisa; Losurdo, Anna; Gnoni, Valentina; Di Blasi, Chiara; Brunetti, Riccardo; Contardi, Anna; Mazza, Salvatore; Della Marca, Giacomo

2014-07-01

165

Thermal acclimation of heart rates in reptilian embryos.  

PubMed

In many reptiles, the thermal regimes experienced by eggs in natural nests vary as a function of ambient weather and location, and this variation has important impacts on patterns of embryonic development. Recent advances in non-invasive measurement of embryonic heart rates allow us to answer a long-standing puzzle in reptilian developmental biology: Do the metabolic and developmental rates of embryos acclimate to local incubation regimes, as occurs for metabolic acclimation by post-hatching reptiles? Based on a strong correlation between embryonic heart rate and oxygen consumption, we used heart rates as a measure of metabolic rate. We demonstrate acclimation of heart rates relative to temperature in embryos of one turtle, one snake and one lizard species that oviposit in relatively deep nests, but found no acclimation in another lizard species that uses shallow (and hence, highly thermally variable) nests. Embryonic thermal acclimation thus is widespread, but not ubiquitous, within reptiles. PMID:21179473

Du, Wei-Guo; Ye, Hua; Zhao, Bo; Warner, Daniel A; Shine, Richard

2010-01-01

166

[Association between level of intelligence and heart rate variability].  

PubMed

Earlier we discovered that heart rate variability was associated with the level of intelligence. The purpose of this study is to confirm this association using more reliable method and to define more precisely the frequency band within which the amplitude of the heart rate modulations is related to intelligence. 13 males (aged 14 to 17) were the study subjects. The total score of the computer game Tetris was taken as a general measure of the intelligence level. Heart rate was recorded electrocardiographically both at rest and during playing Tetris. Frequency analysis of heart rate was carried out with digital Fourier transformation. Correlation analysis showed that there was positive association between the level of intelligence and the amplitude of heart rate modulation at the frequencies 0.30 and 0.15 modulations per RR interval. This association is closer for the heart rate at rest than for the heart rate during mental work and for the frequency 0.30 than for the 0.15 modulations per RR interval. PMID:21961308

Mukhin, V N; Iakovlev, N M

2011-08-01

167

Model-based detection of heart rate turbulence.  

PubMed

In this study, the integral pulse frequency modulation model is extended to account for the presence of ectopic beats and heart rate turbulence (HRT). Based on this model, a new statistical approach to the detection and characterization of HRT is presented. The detector structure involves a set of Karhunen-LoEve basis functions and a generalized likelihood ratio test statistic T(x) . The three most significant basis functions reflect the difference in heart rate prior to a ventricular ectopic beat (VEB) compared to after HRT, the "average" HRT, and a delayed contribution to HRT, respectively. Detector performance was studied on both simulated and ECG signals. Three different simulations were performed for the purpose of studying the influence of SNR, QRS jitter, and ECG sampling rate. The results show that the HRT test statistic T(x) performs better in all simulations than do the commonly used parameters known as turbulence onset (TO) and turbulence slope (TS). In order to attain the same performance as T(x), TS needs at least twice the amount of VEBs for averaging, and TO at least four times. The detector performance was also studied on ECGs acquired from eight patients who underwent hemodialysis treatment with the goal to discriminate between patients considered to be hypotension-resistant (HtR) and hypotension-prone (HtP). The results show that T(x) exhibits larger mean values in HtR patients than in HtP, suggesting that HRT is mostly present in HtR patients. The overlap between the two groups was larger for TO and TS than for T(x). PMID:19126450

Solem, Kristian; Laguna, Pablo; Martínez, Juan Pablo; Sörnmo, Leif

2008-12-01

168

Real-time Continuous Assessment Method for Mental and Physiological Condition using Heart Rate Variability  

NASA Astrophysics Data System (ADS)

It is necessary to monitor the daily health condition for preventing stress syndrome. In this study, it was proposed the method assessing the mental and physiological condition, such as the work stress or the relaxation, using heart rate variability at real time and continuously. The instantanuous heart rate (HR), and the ratio of the number of extreme points (NEP) and the number of heart beats were calculated for assessing mental and physiological condition. In this method, 20 beats heart rate were used to calculate these indexes. These were calculated in one beat interval. Three conditions, which are sitting rest, performing mental arithmetic and watching relaxation movie, were assessed using our proposed algorithm. The assessment accuracies were 71.9% and 55.8%, when performing mental arithmetic and watching relaxation movie respectively. In this method, the mental and physiological condition was assessed using only 20 regressive heart beats, so this method is considered as the real time assessment method.

Yoshida, Yutaka; Yokoyama, Kiyoko; Ishii, Naohiro

169

Autonomic balance revisited: Panic anxiety and heart rate variability  

Microsoft Academic Search

The analysis of heart rate variability (HRV) is becoming widely used in clinical research to provide a window into autonomic control of HR. This technique has been valuable in elucidating the autonomic underpinnings of panic disorder (PD), a condition that is marked by reports of heart palpitations. A body of research has emerged that implicates a relative reduction in HRV

Bruce H. Friedman; JULIAN F. THAYERt

1998-01-01

170

Phase Transition in a Healthy Human Heart Rate  

NASA Astrophysics Data System (ADS)

A healthy human heart rate displays complex fluctuations which share characteristics of physical systems in a critical state. We demonstrate that the human heart rate in healthy individuals undergoes a dramatic breakdown of criticality characteristics, reminiscent of continuous second order phase transitions. By studying the germane determinants, we show that the hallmark of criticality—highly correlated fluctuations—is observed only during usual daily activity, and a breakdown of these characteristics occurs in prolonged, strenuous exercise and sleep. This finding is the first reported discovery of the dynamical phase transition phenomenon in a biological control system and will be a key to understanding the heart rate control system in health and disease.

Kiyono, Ken; Struzik, Zbigniew R.; Aoyagi, Naoko; Togo, Fumiharu; Yamamoto, Yoshiharu

2005-07-01

171

Optimized Treatment and Heart Rate Reduction in Chronic Heart Failure  

PubMed Central

Background Heart failure (HF) is a syndrome that leads to poor outcome in advanced forms. The neurohormonal blockade modifies this natural history; however, it is often suboptimal. Objective The aim of this study is to assess at what percentage cardiologists used to treating HF can prescribe target doses of drugs of proven efficacy. Methods A total of 104 outpatients with systolic dysfunction were consecutively enrolled, all under stabilized treatment. Demographic and treatment data were evaluated and the doses achieved were verified. The findings are shown as percentages and correlations are made between different variables. Results The mean age of patients was 64.1 ± 14.2 years, with SBP =115.4 ± 15.3, HR = 67.8 ± 9.4 bpm, weight = 76.0 ± 17.0 kg and sinus rhythm (90.4%). As for treatment, 93.3% received a RAS blocker (ACEI 52.9%), all received beta-blockers (BB), the most often prescribed being carvedilol (92.3%). As for the doses: 97.1% of those receiving an ARB were below the optimal dose and of those who received ACEI, 52.7% received an optimized dose. As for the BB, target doses were prescribed to 76.0% of them. In this group of patients, most with BB target dose, it can be seen that 36.5% had HR ? 70 bpm in sinus rhythm. Conclusion Cardiologists used to treating HF can prescribe target doses of ACEI and BB to most patients. Even though they receive the recommended doses, about one third of patients persists with HR > 70 bpm and should have their treatment optimized.

Moreno, Irineu Blanco; Del Carlo, Carlos Henrique; Pereira-Barretto, Antonio Carlos

2013-01-01

172

Signal processing methodologies for an acoustic fetal heart rate monitor  

NASA Technical Reports Server (NTRS)

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively 'trained' in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a series of patients. Comparative data provides favorable indications of the feasibility of the acoustic monitor for clinical use.

Pretlow, Robert A., III; Stoughton, John W.

1992-01-01

173

Independent and incremental prognostic value of heart rate variability in patients with chronic heart failure  

Microsoft Academic Search

Background Decreased heart rate variability (HRV), indicating derangement in cardiac autonomic control, has been reported in patients with chronic heart failure. However, the independent and incremental prognostic value of HRV over clinical data and measures of left ventricular dysfunction has been less thoroughly investigated. This study was designed to evaluate the predictive value of HRV and Poincaré plots as assessed

Domenico Bonaduce; Mario Petretta; Fortunato Marciano; Maria L. E. Vicario; Claudio Apicella; Maria A. E. Rao; Emanuele Nicolai; Massimo Volpe

1999-01-01

174

Method of Discriminant Gravity Tolerance using Heart Rate Variability  

NASA Astrophysics Data System (ADS)

When returning on the earth by the space flight, the space deconditioning may be developed. As this countermeasure, the artificial gravity load device using the centrifuge is proposed in the space station. But the gravity load might cause the faint, and safe gravity load is uncertainty. We proposed that discriminate strength of gravity tolerance using heart rate variability time series. Step function was inputted to AR model estimated from heart rate variability time series during rest or under light gravity load, and strength of the gravity tolerance was discriminated by the step response function. On the result, discriminant accuracy was 87.5% by using heart rate variability time series when gravity load of 1.0 G was added to the human lying on the supine. Therefore, possibility of discriminant of gravity tolerance was obtained by using heart rate variability time series when sympathetic hyperactivity. Discriminant of the gravity tolerance is expected before countermeasure of space deconditioning is executed.

Yoshida, Yutaka; Yokoyama, Kiyoko; Takada, Hiroki; Iwase, Satoshi

175

An instantaneous heart-rate meter with digital display  

Microsoft Academic Search

A portable battery-driven instrument is described which displays the instantaneous heart rate in digital form. No controls\\u000a are required except the on\\/off switch and dry electrodes can often be used.

J. Atherton

1975-01-01

176

Heart Rate Response and Lactic Acid Concentration in Squash Players.  

ERIC Educational Resources Information Center

It was concluded that playing squash is an activity that results in heart rate responses of sufficient intensity to elicit aerobic training effects without producing high lactic acid concentration in the blood. (MM)

Beaudin, Paula; And Others

1978-01-01

177

Computer Sleep Stage Classification Using Heart Rate Data.  

National Technical Information Service (NTIS)

The paper explores the possibility of using discriminant analysis and Bayes classification procedures to determine sleep stage using only heart rate data. The recognition of sleep stages or even the ability to differentiate sleep from wakefulness using he...

A. J. Welch P. C. Richardson

1972-01-01

178

Assessment of anxiety using heart rate nonlinear dynamics  

NASA Astrophysics Data System (ADS)

Various anxiety states have been linked with disorders of the autonomic nervous system. These autonomic disorders may be revealed by analysis of physiological time series such as the heart rate interbeat interval series. The present paper reports a general model of biological system functioning and related assessment indices based on recent nonlinear dynamical systems approaches. In particular, two experimental studies are reported which suggest the utility of heart rate nonlinear dynamics in the assessment of anxiety.

Thayer, Julian F.; Friedman, Bruce H.

1993-11-01

179

Heart rate variability in infants, children and young adults  

Microsoft Academic Search

Heart rate variability was studied in normal subjects age 1 month-24 years while awake and in active and quiet sleep using 24 h continuous recordings of the ECG. Variability was quantified by spectral analysis for the two frequency bands: low frequency (LF) 0.03–0.15 Hz, high frequency (HF) 0.15–0.6 Hz. Heart rate variability showed an age dependence, being in general an

John P. Finley; Sherwin T. Nugent

1995-01-01

180

Mental Load and the Measurement of Heart Rate Variability  

Microsoft Academic Search

A number of studies concerning heart rate variability and mental load arereviewedIt is concluded that in paced choice reaction tasks the number of reversal pointsin the cardiotachogram is the most sensitive measure of the load of the task.This measure was strongly correlated with respirationSpectral analysis of heart rate variability revealed the existence of a frequency component at about 0·10 Hz, a

G. MULDER

1973-01-01

181

Digital heart rate measurement based on Atmega16L  

Microsoft Academic Search

The photoelectric heart rate meter reported in this paper picks up heart rate signals with a photoelectric cell, converts them into standard TTL pulse signal, and sends them into the input capture interface of a single-chip computer Atmega16L. Its input capture register can capture the Timer\\/Counter value at a given external (edge triggered) event on the input capture pin (ICP1)

Xiaoqing Zhang; Lishuang Feng; Jiqiang Wang

2008-01-01

182

Complex demodulation of heart rate changes during orthostatic testing  

Microsoft Academic Search

Heart rate changes induced by the standing up of young healthy subjects are processed by a complex demodulation algorithm yielding time-local estimates of the amplitude of the heart-rate variability function. Complex demodulate of the high-frequency band (0.15 to 0.45 Hz) shows an abrupt decrease of amplitude immediately after standing up, presumably due into vagal withdrawal. Complex demodulation of a part

T. Kiauta; F. Jager; W. N. Tapp

1990-01-01

183

Heart rate variability predicts control over memory retrieval.  

PubMed

Stopping retrieval of unwanted memories has been characterized as a process that requires inhibition. However, little research has examined the relationship between control over memory retrieval and individual differences in inhibitory control. Higher levels of resting heart rate variability (HRV) are associated with greater inhibitory control, as indicated by better performance on a number of cognitive, affective, and motor tasks. Therefore, we tested the hypothesis that higher levels of resting HRV predict enhanced memory inhibition as indexed by performance on the think/no-think task. Efforts to suppress no-think word pairs resulted in impaired recall for those items, as in past studies. Moreover, higher levels of resting HRV were associated with more successful suppression, as indicated by lower recall of the to-be-avoided stimuli relative to baseline stimuli. These findings are among the first to suggest that physiological markers of inhibitory control can be used to index a person's capacity to control unwanted memories. PMID:24335601

Gillie, Brandon L; Vasey, Michael W; Thayer, Julian F

2014-02-01

184

Heart rate variability in natural time and 1/f "noise"  

NASA Astrophysics Data System (ADS)

Several studies have shown that heart rate fluctuations exhibit the ubiquitous 1/f behavior which is altered in desease. Furthermore, the analysis of electrocardiograms in natural time reveals that important malfunctions in the complex system of the human heart can be identified. Here, we present a simple evolution model in natural time that exhibits the 1/fa behavior with a close to unity. The results of this model are consistent with a progressive modification of heart rate variability in healthy children and adolescents. The model results in complexity measures that separate healthy dynamics from patients as well as from sudden cardiac death individuals.

Sarlis, N. V.; Skordas, E. S.; Varotsos, P. A.

2009-07-01

185

Human heart rate variability relation is unchanged during motion sickness  

NASA Technical Reports Server (NTRS)

In a study of 18 human subjects, we applied a new technique, estimation of the transfer function between instantaneous lung volume (ILV) and instantaneous heart rate (HR), to assess autonomic activity during motion sickness. Two control recordings of ILV and electrocardiogram (ECG) were made prior to the development of motion sickness. During the first, subjects were seated motionless, and during the second they were seated rotating sinusoidally about an earth vertical axis. Subjects then wore prism goggles that reverse the left-right visual field and performed manual tasks until they developed moderate motion sickness. Finally, ILV and ECG were recorded while subjects maintained a relatively constant level of sickness by intermittent eye closure during rotation with the goggles. Based on analyses of ILV to HR transfer functions from the three conditions, we were unable to demonstrate a change in autonomic control of heart rate due to rotation alone or due to motion sickness. These findings do not support the notion that moderate motion sickness is manifested as a generalized autonomic response.

Mullen, T. J.; Berger, R. D.; Oman, C. M.; Cohen, R. J.

1998-01-01

186

Sympathetic reinnervation and heart rate variability after cardiac transplantation.  

PubMed Central

BACKGROUND: Heart rate variability is thought to measure autonomic modulation, but the relation has never been demonstrated directly in humans. AIM: To test the hypothesis that increased low frequency heart rate variability reflects sympathetic reinnervation after cardiac transplantation. PATIENTS: 24 cardiac transplant recipients at the time of routine surveillance coronary angiography two or more years after cardiac transplantation, and 10 controls with normal coronary arteries undergoing angiography for investigation of chest pain. SETTING: Regional cardiothoracic centre. METHODS: Sympathetic effector function at the sinus node was assessed by measuring the fall in cycle length for two minutes after injection of tyramine to the artery supplying the sinus node. Heart rate variability was measured from three-minute RR interval sequences at rest, during metronomic respiration, and before and after atropine. RESULTS: The logarithm of the low frequency component of heart rate variability during metronomic respiration was linearly related to the logarithm of the change in cycle length after injection of tyramine (R2 = 0.28, P = 0.007). Absolute units more accurately reflected sympathetic effector function than did normalised units or the ratio of low frequency to high frequency. Atropine did not affect high frequency heart rate variability in transplant recipients. CONCLUSIONS: The low frequency component of heart rate variability is directly related to sympathetic reinnervation to the sinus node.

Lord, S. W.; Clayton, R. H.; Mitchell, L.; Dark, J. H.; Murray, A.; McComb, J. M.

1997-01-01

187

Heart Rate Recovery in Asymptomatic Patients with Chagas Disease  

PubMed Central

Background Chagas disease patients with right bundle-branch block (RBBB) have diverse clinical presentation and prognosis, depending on left ventricular (LV) function. Autonomic disorder can be an early marker of heart involvement. The heart rate recovery (HRR) after exercise may identify autonomic dysfunction, with impact on therapeutic strategies. This study was designed to assess the HRR after symptom-limited exercise testing in asymptomatic Chagas disease patients with RBBB without ventricular dysfunction compared to patients with indeterminate form of Chagas disease and healthy controls. Methods One hundred and forty-nine subjects divided into 3 groups were included. A control group was comprised of healthy individuals; group 1 included patients in the indeterminate form of Chagas disease; and group 2 included patients with complete RBBB with or without left anterior hemiblock, and normal ventricular systolic function. A symptom-limited exercise test was performed and heart rate (HR) response to exercise was assessed. HRR was defined as the difference between HR at peak exercise and 1 min following test termination. Results There were no differences in heart-rate profile during exercise between healthy individuals and patients in indeterminate form, whereas patients with RBBB had more prevalence of chronotropic incompetence, lower exercise capacity and lower HRR compared with patients in indeterminate form and controls. A delayed decrease in the HR after exercise was found in 17 patients (15%), 9% in indeterminate form and 24% with RBBB, associated with older age, worse functional capacity, impaired chronotropic response, and ventricular arrhythmias during both exercise and recovery. By multivariable analysis, the independent predictors of a delayed decrease in the HRR were age (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.03 to 1.21; p?=?0.010) and presence of RBBB (OR 3.97; 95% CI 1.05 to 15.01; p?=?0.042). Conclusions A small proportion (15%) of asymptomatic Chagas patients had attenuated HRR after exercise, being more prevalent in patients with RBBB compared with patients in indeterminate form and controls.

de Alencar, Maria Clara Noman; Rocha, Manoel Otavio da Costa; Lima, Marcia Maria de Oliveira; Costa, Henrique Silveira; Sousa, Giovane Rodrigo; Carneiro, Renata de Carvalho Bicalho; Silva, Guilherme Canabrava Rodrigues; Brandao, Fernando Vieira; Kreuser, Lucas Jordan; Ribeiro, Antonio Luiz Pinho; Nunes, Maria Carmo Pereira

2014-01-01

188

Interrelation between donor and recipient heart rates during exercise after heterotopic cardiac transplantation  

Microsoft Academic Search

The interrelation between the rates of the innervated recipient heart and the denervated donor heart at rest, on standing, and during the different phases of maximal exercise was studied in nine patients 1-6 months after heterotopic cardiac transplantation. The resting heart rate was significantly higher in the donor heart compared with the recipient heart. Eight of the nine recipient hearts

S Yusuf; A Mitchell; M H Yacoub

1985-01-01

189

Gender- and age-related differences in heart rate dynamics: are women more complex than men?  

NASA Technical Reports Server (NTRS)

OBJECTIVES. This study aimed to quantify the complex dynamics of beat-to-beat sinus rhythm heart rate fluctuations and to determine their differences as a function of gender and age. BACKGROUND. Recently, measures of heart rate variability and the nonlinear "complexity" of heart rate dynamics have been used as indicators of cardiovascular health. Because women have lower cardiovascular risk and greater longevity than men, we postulated that there are important gender-related differences in beat-to-beat heart rate dynamics. METHODS. We analyzed heart rate dynamics during 8-min segments of continuous electrocardiographic recording in healthy young (20 to 39 years old), middle-aged (40 to 64 years old) and elderly (65 to 90 years old) men (n = 40) and women (n = 27) while they performed spontaneous and metronomic (15 breaths/min) breathing. Relatively high (0.15 to 0.40 Hz) and low (0.01 to 0.15 Hz) frequency components of heart rate variability were computed using spectral analysis. The overall "complexity" of each heart rate time series was quantified by its approximate entropy, a measure of regularity derived from nonlinear dynamics ("chaos" theory). RESULTS. Mean heart rate did not differ between the age groups or genders. High frequency heart rate power and the high/low frequency power ratio decreased with age in both men and women (p < 0.05). The high/low frequency power ratio during spontaneous and metronomic breathing was greater in women than men (p < 0.05). Heart rate approximate entropy decreased with age and was higher in women than men (p < 0.05). CONCLUSIONS. High frequency heart rate spectral power (associated with parasympathetic activity) and the overall complexity of heart rate dynamics are higher in women than men. These complementary findings indicate the need to account for gender-as well as age-related differences in heart rate dynamics. Whether these gender differences are related to lower cardiovascular disease risk and greater longevity in women requires further study.

Ryan, S. M.; Goldberger, A. L.; Pincus, S. M.; Mietus, J.; Lipsitz, L. A.

1994-01-01

190

Validity of a heart rate monitor during work in the laboratory and on the Space Shuttle  

NASA Technical Reports Server (NTRS)

Accurate heart rate measurement during work is required for many industrial hygiene and ergonomics situations. The purpose of this investigation was to determine the validity of heart rate measurements obtained by a simple, lightweight, commercially available wrist-worn heart rate monitor (HRM) during work (cycle exercise) sessions conducted in the laboratory and also during the particularly challenging work environment of space flight. Three different comparisons were made. The first compared HRM data to simultaneous electrocardiogram (ECG) recordings of varying heart rates that were generated by an ECG simulator. The second compared HRM data to ECG recordings collected during work sessions of 14 subjects in the laboratory. Finally, ECG downlink and HRM data were compared in four astronauts who performed cycle exercise during space flight. The data were analyzed using regression techniques. The results were that the HRM recorded virtually identical heart rates compared with ECG recordings for the data set generated by an ECG simulator. The regression equation for the relationship between ECG versus HRM heart rate data during work in the laboratory was: ECG HR = 0.99 x (HRM) + 0.82 (r2 = 0.99). Finally, the agreement between ECG downlink data and HRM data during space flight was also very high, with the regression equation being: Downlink ECG HR = 1.05 x (HRM) -5.71 (r2 = 0.99). The results of this study indicate that the HRM provides accurate data and may be used to reliably obtain valid data regarding heart rate responses during work.

Moore, A. D. Jr; Lee, S. M.; Greenisen, M. C.; Bishop, P.

1997-01-01

191

Stretching increases heart rate variability in healthy athletes complaining about limited muscular flexibility  

Microsoft Academic Search

An increase in muscular flexibility, as well as a significant beneficial effect on heart rate and heart rate variability (HRV), was observed in healthy male athletes after performing a standardized 15-minute stretching-program over a period of 28 days. We believe the HRV increase to be due, at least in part, to the improved vagal and\\/or diminished sympathetic control. Therefore, we

Michael Mueck-Weymann; G. Janshoff; H. Mueck

2004-01-01

192

Nonlinear systems dynamics in cardiovascular physiology: The heart rate delay map and lower body negative pressure  

NASA Technical Reports Server (NTRS)

A preliminary study of the applicability of nonlinear dynamic systems analysis techniques to low body negative pressure (LBNP) studies. In particular, the applicability of the heart rate delay map is investigated. It is suggested that the heart rate delay map has potential as a supplemental tool in the assessment of subject performance in LBNP tests and possibly in the determination of susceptibility to cardiovascular deconditioning with spaceflight.

Hooker, John C.

1990-01-01

193

The relationship between anaerobic threshold and heart rate linearity during cycle ergometry  

Microsoft Academic Search

Summary  Recent studies have demonstrated there is a definitive deflection in the heart rate response to incremental velocity work\\u000a that coincides with the anaerobic threshold. These studies were conducted with elite athletes who performed the specific activities\\u000a in which they were trained. The purpose of this study was to determine if the same relationship in heart rate and ventilatory\\u000a response to

K. T. Francis; P. R. McClatchey; J. R. Sumsion; D. E. Hansen

1989-01-01

194

Running velocities and heart rates at fixed blood lactate concentrations in young soccer players  

Microsoft Academic Search

The purpose of this study was to examine the running velocities and heart rates at fixed lactate concentrations of young soccer\\u000a players according to playing position and age. A total of 223 young male soccer players participated in this study. Each player\\u000a performed incremental exercise tests on a treadmill. Running velocities and heart rates at 2 mmol\\/L?1, 2.5 mmol\\/L?1, 3

Rustu Guner; Burak Kunduracioglu; Bülent Ulkar

2006-01-01

195

Automated Fetal Heart Rate Analysis in Labor: Decelerations and Overshoots  

NASA Astrophysics Data System (ADS)

Electronic fetal heart rate (FHR) recording is a standard way of monitoring fetal health in labor. Decelerations and accelerations usually indicate fetal distress and normality respectively. But one type of acceleration may differ, namely an overshoot that may atypically reflect fetal stress. Here we describe a new method for detecting decelerations, accelerations and overshoots as part of a novel system for computerized FHR analysis (OxSyS). There was poor agreement between clinicians when identifying these FHR features visually, which precluded setting a gold standard of interpretation. We therefore introduced `modified' Sensitivity (SE°) and `modified' Positive Predictive Value (PPV°) as appropriate performance measures with which the algorithm was optimized. The relation between overshoots and fetal compromise in labor was studied in 15 cases and 15 controls. Overshoots showed promise as an indicator of fetal compromise. Unlike ordinary accelerations, overshoots cannot be considered to be reassuring features of fetal health.

Georgieva, A. E.; Payne, S. J.; Moulden, M.; Redman, C. W. G.

2010-10-01

196

Effect of bucindolol on heart failure outcomes and heart rate response in patients with reduced ejection fraction heart failure and atrial fibrillation  

PubMed Central

Aims There is little evidence of beta-blocker treatment benefit in patients with heart failure and reduced left ventricular ejection fraction (HFREF) and atrial fibrillation (AF). We investigated the effects of bucindolol in HFREF patients with AF enrolled in the Beta-blocker Evaluation of Survival Trial (BEST). Methods and results A post-hoc analysis of patients in BEST with and without AF was performed to estimate the effect of bucindolol on mortality and hospitalization. Patients were also evaluated for treatment effects on heart rate and the influence of beta1-adrenergic receptor position 389 (?1389) arginine (Arg) vs. glycine (Gly) genotypes. In the 303/2708 patients in AF, patients receiving bucindolol were more likely to achieve a resting heart rate ?80 b.p.m. at 3 months (P < 0.005) in the absence of treatment-limiting bradycardia. In AF patients and sinus rhythm (SR) patients who achieved a resting heart rate ?80 b.p.m., there were beneficial treatment effects on cardiovascular mortality/cardiovascular hospitalization [hazard ratio (HR) 0.61, P = 0.025, and 0.79, P = 0.002]. Without achieving a resting heart rate ?80 b.p.m., there were no treatment effects on events in either group. ?1389-Arg/Arg AF patients had nominally significant reductions in all-cause mortality/HF hospitalization and cardiovascular mortality/hospitalization with bucindolol (HR 0.23, P = 0.037 and 0.28, P = 0.039), whereas Gly carriers did not. There was no evidence of diminished heart rate response in ?1389-Arg homozygotes. Conclusion In HFREF patients with AF, bucindolol was associated with reductions in composite HF endpoints in those who achieved a resting heart rate ?80 b.p.m. and nominally in those with the ?1389-Arg homozygous genotype.

Kao, David P.; Davis, Gordon; Aleong, Ryan; O'Connor, Christopher M.; Fiuzat, Mona; Carson, Peter E.; Anand, Inder S.; Plehn, Jonathan F.; Gottlieb, Stephen S.; Silver, Marc A.; Lindenfeld, JoAnn; Miller, Alan B.; White, Michel; Murphy, Guinevere A.; Sauer, Will; Bristow, Michael R.

2013-01-01

197

Resting heart rate in apparently healthy middle-aged men  

Microsoft Academic Search

Summary  Resting heart rate (fcrest) was measured by a standardized technique in 2,014 men aged 40–59 years during a cardiovascular survey. All men were thought to be healthy prior to the survey examination. According to the survey findings, the material was subdivided into 5 clinical subgroups, according to survey findings of coronary heart disease (CHD), or suspect symptoms, or signs. Coronary

Jan Erikssen; Kaare Rodahl

1979-01-01

198

Heart rate variability and target organ damage in hypertensive patients  

PubMed Central

Background We evaluated the association between linear standard Heart Rate Variability (HRV) measures and vascular, renal and cardiac target organ damage (TOD). Methods A retrospective analysis was performed including 200 patients registered in the Regione Campania network (aged 62.4?±?12, male 64%). HRV analysis was performed by 24-h holter ECG. Renal damage was assessed by estimated glomerular filtration rate (eGFR), vascular damage by carotid intima-media thickness (IMT), and cardiac damage by left ventricular mass index. Results Significantly lower values of the ratio of low to high frequency power (LF/HF) were found in the patients with moderate or severe eGFR (p-value?heart were found in patients with plaque compared to those with a normal IMT (p-value <0.05). These associations remained significant after adjustment for other factors known to contribute to the development of target organ damage, such as age. Moreover, depressed LF/HF was found also in patients with left ventricular hypertrophy but this association was not significant after adjustment for other factors. Conclusions Depressed HRV appeared to be associated with vascular and renal TOD, suggesting the involvement of autonomic imbalance in the TOD. However, as the mechanisms by which abnormal autonomic balance may lead to TOD, and, particularly, to renal organ damage are not clearly known, further prospective studies with longitudinal design are needed to determine the association between HRV and the development of TOD.

2012-01-01

199

Concurrent validity of the Armour39 heart rate monitor strap.  

PubMed

New technology offers potential advantages in physically demanding environments where convenience and comfort are important and accurate and reliable data collection is challenging. Nevertheless, it is important to validate the accuracy and reliability of such biological monitoring systems (BMS) before they are adopted. The purpose of this investigation was to assess the concurrent validity of a new heart rate monitor across a range of exercise intensities and with a large and diverse group of male subjects in a large cohort with diverse physical fitness characteristics. Seventy-five men (age, 23 ± 4 years; height, 181 ± 8 cm; body mass, 83 ± 12 kg; estimated V[Combining Dot Above]O2peak, 3.16 ± 0.63 [L·min]) volunteered and completed a graded cycle ergometer exercise protocol while heart rate was continuously monitored before, during, and after exercise with the new device (Armour39) and the gold standard (electrocardiogram). The 2-minute stages included sitting, standing, and cycling with 35 W increments until volitional fatigue. The coefficient of determination between mean heart rate values at each stage was R = 0.99, whereas Pearson correlations (r) at each stage were ? 0.99. Heart rates during exercise were typically within 1 beat of each other. The Armour39 BMS, therefore, is an acceptable means for the valid and reliable determination of heart rate under various bodily positions and levels of exertion, including maximal exercise intensity. PMID:23860286

Flanagan, Shawn D; Comstock, Brett A; Dupont, William H; Sterczala, Adam R; Looney, Dave P; Dombrowski, Dylan H; McDermott, Danielle M; Bryce, Alexander; Maladouangdock, Jesse; Dunn-Lewis, Courtenay; Luk, Hui-Ying; Szivak, Tunde K; Hooper, David R; Kraemer, William J

2014-03-01

200

A comparison of heart rate responses in racquet games.  

PubMed Central

The present study investigated the heart rate response to playing tennis with special reference to the skill levels and ages of the participants. Data obtained in a similar manner during earlier studies of badminton and squash players were compared with that obtained during tennis. The number of rallies, mean rally time and actual playing time in 30 minutes of play was also compared for the different skill levels and sports. Results showed that playing tennis raised the players' heart rates to 68-70% of their predicted maximum heart rate (PMHR). Playing squash and badminton could raise heart rates to 80-85% of the players' PMHR which was significantly higher than the values obtained for tennis. The actual skill level of the participants within their chosen sport did not have a significant effect in predicting the physical demands of squash or tennis but was important in predicting the heart rate response of badminton players. The more skillful the badminton player the greater the cardiac response as a result of game play. Analysis of time spent in actual play revealed that tennis players were involved in play for only five of the thirty minutes of game play, compared to 15 and 10 min respectively for squash and badminton. Skill level within each sport was only a significant factor in predicting length of play for squash players in which the medium and highly skilled groups played significantly longer than those of a lower level of skill. Images p96-a

Docherty, D.

1982-01-01

201

A comparison of heart rate responses in racquet games.  

PubMed

The present study investigated the heart rate response to playing tennis with special reference to the skill levels and ages of the participants. Data obtained in a similar manner during earlier studies of badminton and squash players were compared with that obtained during tennis. The number of rallies, mean rally time and actual playing time in 30 minutes of play was also compared for the different skill levels and sports. Results showed that playing tennis raised the players' heart rates to 68-70% of their predicted maximum heart rate (PMHR). Playing squash and badminton could raise heart rates to 80-85% of the players' PMHR which was significantly higher than the values obtained for tennis. The actual skill level of the participants within their chosen sport did not have a significant effect in predicting the physical demands of squash or tennis but was important in predicting the heart rate response of badminton players. The more skillful the badminton player the greater the cardiac response as a result of game play. Analysis of time spent in actual play revealed that tennis players were involved in play for only five of the thirty minutes of game play, compared to 15 and 10 min respectively for squash and badminton. Skill level within each sport was only a significant factor in predicting length of play for squash players in which the medium and highly skilled groups played significantly longer than those of a lower level of skill. PMID:7104564

Docherty, D

1982-06-01

202

Short-Term Heart Rate Variability Strongly Predicts Sudden Cardiac Death in Chronic Heart Failure Patients  

Microsoft Academic Search

Background—The predictive value of heart rate variability (HRV) in chronic heart failure (CHF) has never been tested in a comprehensive multivariate model using short-term laboratory recordings designed to avoid the confounding effects of respiration and behavioral factors. Methods and Results—A multivariate survival model for the identification of sudden (presumably arrhythmic) death was developed with data from 202 consecutive patients referred

Maria Teresa La Rovere; Gian Domenico Pinna; Roberto Maestri; Andrea Mortara; Soccorso Capomolla; Oreste Febo; Roberto Ferrari; Mariella Franchini; Marco Gnemmi; Cristina Opasich; Pier Giorgio Riccardi; Egidio Traversi; Franco Cobelli

203

Classification of heart rate variability in patients with mild hypertension.  

PubMed

The diagnostic performance of two pattern classification methods to detect hypertension was evaluated in a population of 29 mildly hypertensive and 20 normal subjects. The heart rate variability (HRV) signal of each subject was recorded during rest and isometric handgrip exercise. Feature vectors composed of up to 6 features from both the time and frequency domain representation of the HRV signal were constructed and applied to a Bayes' likelihood classifier and a voting k-nearest neighbours classifier. Each subject was classified as hypertensive or normal, and the classification compared to the clinical diagnosis for each subject. The diagnostic performance of each classifier/feature vector combination was evaluated using the leave-one-out method. The best performance of 90% correct classifications was achieved using a nearest neighbour classifier, a Euclidean distance metric and 3 features. The Bayes' classifier achieved a best performance of 84% correct classification. The work shows promise for the detection of the autonomic disturbance which precedes and accompanies the hypertensive state. PMID:9503692

Raymond, B; Taverner, D; Nandagopal, D; Mazumdar, J

1997-12-01

204

Kramers-Moyal Expansion of Heart Rate Variability  

NASA Astrophysics Data System (ADS)

The first six Kramers-Moyal coefficients were extracted from human heart rate variability recordings. The method requires the determination of the Markov time and of the proper conditional probability densities. We analyzed heart rate data recorded in a group of ten young, healthy subjects. We obtained non-negligible higher order Kramers-Moyal (K-M) terms in 6 h nighttime parts of the 24 h recordings. This indicates that the data is a non-Gaussian process and probably a correlated signal. The analysis yielded important new insights into the character and distribution of the stochastic processes measured in healthy group. In the night hours, the dominant oscillation in the heart rate is the so called respiratory sinus arrhythmia (RSA) -- a physiological phenomenon in which respiration acts as a drive for the heart rate. Certain kinds of pathology may disrupt RSA. We compared nighttime recordings of the healthy group with those recorded in six patients with hypertrophic cardiomyopathy (HCM). HCM is generally a pathology of heart cells but abnormalities in autonomic regulation are also observed. Using the higher order Kramers-Moyal coefficients, we analyzed the skewness and kurtosis in the nighttime recordings for the normal subjects.

Petelczyc, M.; ?ebrowski, J. J.; Baranowski, R.

2009-05-01

205

Impaired heart rate recovery in patients with endemic fluorosis.  

PubMed

The objective of the present study was to determine the heart rate recovery index (HRRI), a marker of autonomic nervous system function in patients with endemic fluorosis. Forty patients with endemic fluorosis (16 men/24 women) and 40 age-, sex-, and body mass index-matched healthy controls (16 men/24 women) with normal fluoride intake were enrolled in this study. HRRI was calculated by subtracting the heart rate values at the first, second, and third minutes of the recovery phase from the peak heart rate (HRRI 1, HRRI 2, HRRI 3). Urine fluoride levels of fluorosis patients were significantly (P?

Adali, M Koray; Varol, Ercan; Aksoy, Fatih; Icli, Atilla; Ersoy, I Hakki; Ozaydin, Mehmet; Erdogan, Dogan; Dogan, Abdullah

2013-06-01

206

Age related reference ranges for respiration rate and heart rate from 4 to 16 years  

PubMed Central

Background: Clinical vital signs in children (temperature, heart rate, respiration rate, and blood pressure) are an integral part of clinical assessment of degree of illness or normality. Despite this, only blood pressure and temperature have a reliable evidence base. The accepted ranges of heart and respiration rate vary widely. Methods: This study examined 1109 children aged 4–16 years in their own schools. Age, sex, height, weight, and resting respiration rate and heart rate were recorded. The data were used to produce age related reference ranges for everyday clinical use. Results: Reference intervals are presented for the range of heart rate and respiration rate of healthy resting children aged 4–16 years. The recorded values are at variance with standard quoted ranges in currently available texts.

Wallis, L; Healy, M; Undy, M; Maconochie, I

2005-01-01

207

Prospective Study of Heart Rate Variability and Mortality in Chronic Heart Failure Results of the United Kingdom Heart Failure Evaluation and Assessment of Risk Trial (UK-Heart)  

Microsoft Academic Search

Background—Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the value of heart rate variability (HRV) measures as independent predictors of death in CHF. Methods and Results—In a prospective study powered for mortality, we recruited 433 outpatients 62 69.6 years old

James Nolan; Phillip D. Batin; Richard Andrews; Steven J. Lindsay; Paul Brooksby; Michael Mullen; Wazir Baig; Andrew D. Flapan; Alan Cowley; Robin J. Prescott; James M. M. Neilson; Keith A. A. Fox

208

Pathophysiology of exercise heart rate recovery: a comprehensive analysis.  

PubMed

Expanded use of exercise heart rate recovery (HRR) has renewed interest in the pathophysiology of heart rate control. This study uses basic physiologic principles to construct a unique model capable of describing the full time course of sympathetic and parasympathetic activity during HRR. The model is tested in a new study of 22 diverse subjects undergoing both maximal and submaximal treadmill exercise. Based on this analysis, prolongation of HRR involves changes within the sinus node, changes in sympathetic function, in parasympathetic function, and in the central mechanisms regulating autonomic balance. The methods may provide unique insight into alterations in autonomic control in health and disease. PMID:23530480

Pierpont, Gordon L; Adabag, Selcuk; Yannopoulos, Demetri

2013-03-01

209

Robust efficient estimation of heart rate pulse from video  

PubMed Central

We describe a simple but robust algorithm for estimating the heart rate pulse from video sequences containing human skin in real time. Based on a model of light interaction with human skin, we define the change of blood concentration due to arterial pulsation as a pixel quotient in log space, and successfully use the derived signal for computing the pulse heart rate. Various experiments with different cameras, different illumination condition, and different skin locations were conducted to demonstrate the effectiveness and robustness of the proposed algorithm. Examples computed with normal illumination show the algorithm is comparable with pulse oximeter devices both in accuracy and sensitivity.

Xu, Shuchang; Sun, Lingyun; Rohde, Gustavo Kunde

2014-01-01

210

Robust efficient estimation of heart rate pulse from video.  

PubMed

We describe a simple but robust algorithm for estimating the heart rate pulse from video sequences containing human skin in real time. Based on a model of light interaction with human skin, we define the change of blood concentration due to arterial pulsation as a pixel quotient in log space, and successfully use the derived signal for computing the pulse heart rate. Various experiments with different cameras, different illumination condition, and different skin locations were conducted to demonstrate the effectiveness and robustness of the proposed algorithm. Examples computed with normal illumination show the algorithm is comparable with pulse oximeter devices both in accuracy and sensitivity. PMID:24761294

Xu, Shuchang; Sun, Lingyun; Rohde, Gustavo Kunde

2014-04-01

211

Estimating Energy Expenditure from Heart Rate in Older Adults: A Case for Calibration  

PubMed Central

Background Accurate measurement of free-living energy expenditure is vital to understanding changes in energy metabolism with aging. The efficacy of heart rate as a surrogate for energy expenditure is rooted in the assumption of a linear function between heart rate and energy expenditure, but its validity and reliability in older adults remains unclear. Objective To assess the validity and reliability of the linear function between heart rate and energy expenditure in older adults using different levels of calibration. Design Heart rate and energy expenditure were assessed across five levels of exertion in 290 adults participating in the Baltimore Longitudinal Study of Aging. Correlation and random effects regression analyses assessed the linearity of the relationship between heart rate and energy expenditure and cross-validation models assessed predictive performance. Results Heart rate and energy expenditure were highly correlated (r?=?0.98) and linear regardless of age or sex. Intra-person variability was low but inter-person variability was high, with substantial heterogeneity of the random intercept (s.d.?=?0.372) despite similar slopes. Cross-validation models indicated individual calibration data substantially improves accuracy predictions of energy expenditure from heart rate, reducing the potential for considerable measurement bias. Although using five calibration measures provided the greatest reduction in the standard deviation of prediction errors (1.08 kcals/min), substantial improvement was also noted with two (0.75 kcals/min). Conclusion These findings indicate standard regression equations may be used to make population-level inferences when estimating energy expenditure from heart rate in older adults but caution should be exercised when making inferences at the individual level without proper calibration.

Schrack, Jennifer A.; Zipunnikov, Vadim; Goldsmith, Jeff; Bandeen-Roche, Karen; Crainiceanu, Ciprian M.; Ferrucci, Luigi

2014-01-01

212

Age effects on interrelationships between lung volume and heart rate during standing  

Microsoft Academic Search

terize the effects of aging on autonomic mediation of heart rate, lung volume, and interrelationships be- tween lung volume and heart rate, we analyzed spec- tral properties of respiration and heart rate and mod- eled interrelationships between respiration and heart rate in healthy young and older subjects in response to movement from the supine to standing positions. Our results demonstrating

GARRETT STANLEY; DAVIDE VEROTTA; NOAH CRAFT; RONALD A. SIEGEL; JANICE B. SCHWARTZ

1997-01-01

213

Heart rate variability and cognitive function: effects of physical effort.  

PubMed

This study investigated alterations in heart rate variability (HRV) and cognitive performance before and after physical effort, for 30 high-level track and field athletes (23 males and 7 females). Interbeat intervals were assessed at the baseline and during each task of a CogState cognitive battery (simple reaction time, choice reaction time, working memory, short-term memory and sustained attention). Time and frequency domain measures of HRV were compared between conditions and between tasks. The results indicated differences in HRV between executive and non-executive tasks. There was a significant increase in sympathetic-modulation-related indices after physical effort. The differences between executive and non-executive tasks were the same in post-test. Correlations were found between HRV and cognitive performance, which differed by speed and accuracy. We conclude that HRV is related to cognitive demand and that the correlation between HRV and cognitive performance seems to be stronger after physical exercise. The results raise questions about the psychophysiological meaning of different HRV signals and this has implications for future research about the relationship between HRV and cognition. PMID:19632295

Luft, Caroline Di Bernardi; Takase, Emílio; Darby, David

2009-10-01

214

Adjusting heart rate during sleep using activity variance.  

PubMed

In order to mimic the natural decrease in heart rate that occurs during sleep, an algorithm was devised to decrease the base rate to a programmable sleep rate. The algorithm was developed using activity and sinus rate data obtained from 18 normal subjects ranging in age from 22-80 years. The data were recorded in the event record of a "taped-on" pacemaker. The surface ECG signal was used to inhibit a pacer programmed to VVI at 45 ppm. The ECG documented the sinus rate while the accelerometer-based activity signals were recorded in an event record. An algorithm was used to estimate the smoothed acceleration variance every 26 seconds. The activity variance was stored in a histogram. Results: The lower 7/24ths of the histogram entries were primarily attributable to sleep. If the activity variance was entered into the lower 7/24ths of the histogram and the accelerometer reading was below rate responsive threshold, the base rate was switched to sleep rate. Using least mean squares to estimate optimal slope, base rate, and sleep rate, the root mean square error between activity derived heart rate and sinus rate was 12 beats/min. Conclusion: This study supports using an estimate of activity variance to automatically decrease pacing rate below programmed base rate. This decrease may be actuated during an afternoon nap or nighttime sleep. PMID:7845794

Bornzin, G A; Arambula, E R; Florio, J; Levine, P A; Hauck, G

1994-11-01

215

Remote Measurements of Heart and Respiration Rates for Telemedicine  

PubMed Central

Non-contact and low-cost measurements of heart and respiration rates are highly desirable for telemedicine. Here, we describe a novel technique to extract blood volume pulse and respiratory wave from a single channel images captured by a video camera for both day and night conditions. The principle of our technique is to uncover the temporal dynamics of heart beat and breathing rate through delay-coordinate transformation and independent component analysis-based deconstruction of the single channel images. Our method further achieves robust elimination of false positives via applying ratio-variation probability distributions filtering approaches. Moreover, it enables a much needed low-cost means for preventing sudden infant death syndrome in new born infants and detecting stroke and heart attack in elderly population in home environments. This noncontact-based method can also be applied to a variety of animal model organisms for biomedical research.

Qian, Yi; Tsien, Joe Z.

2013-01-01

216

Conditional mutual information-based feature selection for congestive heart failure recognition using heart rate variability.  

PubMed

Feature selection plays an important role in pattern recognition systems. In this study, we explored the problem of selecting effective heart rate variability (HRV) features for recognizing congestive heart failure (CHF) based on mutual information (MI). The MI-based greedy feature selection approach proposed by Battiti was adopted in the study. The mutual information conditioned by the first-selected feature was used as a criterion for feature selection. The uniform distribution assumption was used to reduce the computational load. And, a logarithmic exponent weighting was added to model the relative importance of the MI with respect to the number of the already-selected features. The CHF recognition system contained a feature extractor that generated four categories, totally 50, features from the input HRV sequences. The proposed feature selector, termed UCMIFS, proceeded to select the most effective features for the succeeding support vector machine (SVM) classifier. Prior to feature selection, the 50 features produced a high accuracy of 96.38%, which confirmed the representativeness of the original feature set. The performance of the UCMIFS selector was demonstrated to be superior to the other MI-based feature selectors including MIFS-U, CMIFS, and mRMR. When compared to the other outstanding selectors published in the literature, the proposed UCMIFS outperformed them with as high as 97.59% accuracy in recognizing CHF using only 15 features. The results demonstrated the advantage of using the recruited features in characterizing HRV sequences for CHF recognition. The UCMIFS selector further improved the efficiency of the recognition system with substantially lowered feature dimensions and elevated recognition rate. PMID:22261219

Yu, Sung-Nien; Lee, Ming-Yuan

2012-10-01

217

Developmental and Gender Differences in the Relationship of Behavior Pattern to Heart Rate Reactivity between Two Teenage Samples.  

ERIC Educational Resources Information Center

Assessed Type A behavior pattern for 122 teenagers who had heart rate measured during rest and presentation of mental arithmetic stressor under timed and competitive conditions. Examined whether sex, age, task performance, and behavior pattern predicted heart rate reactivitiy. Found no significant main effects for behavior pattern, sex, or age;…

Sharpley, Christopher F.; And Others

1993-01-01

218

Autonomic nervous control of the heart rate response to dynamic incremental exercise: evaluation of the Rosenblueth-Simeone model  

Microsoft Academic Search

Summary  To evaluate the validity of the Rosenblueth-Simeone model for the heart rate response to incremental dynamic exercise, 11 healthy men performed maximal exercise tests on a cycle ergometer after administration of placebo, propranolol, atropine or both propranolol and atropine. The model showed that the influence of sympathetic activity on heart rate increased at intensities up to those which resulted in

Jorge Pinto Ribeiro; José Manuel Ibáñez; Ricardo Stein

1991-01-01

219

Inhalation of ultrafine carbon particles alters heart rate and heart rate variability in people with type 2 diabetes  

PubMed Central

Background Diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ?100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects. Methods 17 never-smoker subjects 30–60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0–10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure. Results Analysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p?=?0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p?=?0.045). There were no UFP effects on cardiac rhythm or repolarization. Conclusions Inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure.

2014-01-01

220

When heart goes "BOOM" to fast. Heart rate greater than 80 as mortality predictor in acute myocardial infarction  

PubMed Central

Many prospective studies established association between high heart rate and increased cardiovascular morbidity and mortality, independently of other risk factors. Heart rate over 80 beats per minute more often leads to atherosclerotic plaque disruption, the main step in developing acute coronary syndrome. Purpose was to investigate the incidence of higher heart rate levels in patients with anterior wall acute myocardial infarction with ST-segment elevation and the influence of heart rate on mortality. Research included 140 patients with anterior wall acute myocardial infarction with ST-segment elevation treated in Coronary Unit, Clinical Center Kragujevac in the period from January 2001-June 2006. Heart rate was calculated as the mean value of baseline and heart rate in the first 30 minutes after admission. Other risk factors were also followed to determine their connection with elevated heart rate. Results showed that the majority of patients survived (over 70%). In a total number of patients, more than 75% had a heart rate levels greater than 80 beats per minute. There was a significant difference in heart rate on addmision between survivors and patients who died, with a greater levels in patients with fatal outcome. Both, univariate and multivariate regression analysis singled out heart rate greater than 80 beats per minute as independent mortality predictor in these patients. Heart rate greater than 80 beats per minute is a major, independent risk factor for morbidity and important predictor of mortality in patients with acute myocardial infarction.

Davidovic, Goran; Iric-Cupic, Violeta; Milanov, Srdjan; Dimitijevic, Aleksandra; Petrovic-Janicijevic, Mirjana

2013-01-01

221

Circadian Variation of Heart Rate Variability Across Sleep Stages  

PubMed Central

Study Objectives: Nocturnal cardiovascular events are more frequent at the beginning and end of the night. It was proposed that this pattern reflects the nocturnal distribution of sleep and sleep stages. Using heart rate variability (HRV), we recently showed an interaction between the circadian system and vigilance states on the regulation of cardiac rhythmicity. Here, we further investigate this interaction in order to clarify the specific effects of sleep stages on the regulation of the heart. Design: Participants underwent a 72-h ultradian sleep-wake cycle procedure in time isolation consisting of alternating 60-min wake episodes in dim light and 60-min nap opportunities in total darkness. Setting: Time isolation suite. Patients or participants: Fifteen healthy young participants; two were subsequently excluded. Interventions: N/A. Measurements and Results: The current study revealed that sleep onset and progression to deeper sleep stages was associated with a shift toward greater parasympathetic modulation, whereas rapid eye movement (REM) sleep was associated with a shift toward greater sympathetic modulation. We found a circadian rhythm of heart rate (HR) and high-frequency power during wakefulness and all non-REM sleep stages. A significant circadian rhythm of HR and sympathovagal balance of the heart was also observed during REM sleep. During slow wave sleep, maximal parasympathetic modulation was observed at ?02:00, whereas during REM sleep, maximal sympathetic modulation occurred in the early morning. Conclusion: The circadian and sleep stage-specific effects on heart rate variability are clinically relevant and contribute to the understanding of the degree of cardiovascular vulnerability during sleep. Citation: Boudreau P; Yeh WH; Dumont GA; Boivin DB. Circadian variation of heart rate variability across sleep stages. SLEEP 2013;36(12):1919-1928.

Boudreau, Philippe; Yeh, Wei-Hsien; Dumont, Guy A.; Boivin, Diane B.

2013-01-01

222

Evaluation of cardiac autonomic functions in patients with ankylosing spondylitis via heart rate recovery and heart rate variability  

Microsoft Academic Search

Objective  The aim of this study was to evaluate heart rate variability (HRV) and heart rate recovery (HRR) in otherwise healthy ankylosing\\u000a spondlitis (AS) patients and control subjects.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A total of 28 patients with AS and 30 volunteers matched for age and sex were enrolled. All subjects underwent HRV analysis,\\u000a exercise testing (ET), and transthoracic echocardiography. HRR indices were calculated by

Ergun Baris Kaya; Sercan Okutucu; Hakan Aksoy; Ugur Nadir Karakulak; Erol Tulumen; Oya Ozdemir; Fatma Inanici; Kudret Aytemir; Giray Kabakci; Lale Tokgozoglu; Hilmi Ozkutlu; Ali Oto

2010-01-01

223

Severe depression is associated with markedly reduced heart rate variability in patients with stable coronary heart disease  

Microsoft Academic Search

Objective: The purpose of this study was to investigate the relationship between depression and heart rate variability in cardiac patients. Methods: Heart rate variability was measured during 24-hour ambulatory electrocardiographic (ECG) monitoring in 40 medically stable out-patients with documented coronary heart disease meeting current diagnostic criteria for major depression, and 32 nondepressed, but otherwise comparable, patients. Patients discontinued ?-blockers and

Phyllis K Stein; Robert M Carney; Kenneth E Freedland; Judith A Skala; Allan S Jaffe; Robert E Kleiger; Jeffrey N Rottman

2000-01-01

224

Heart Rate Monitors Promote Physical Education for Children  

ERIC Educational Resources Information Center

National health and fitness data suggests that a significant percentage of children are not on a pathway to leading healthy, physically active lifestyles. Many children are leading sedentary lifestyles due to a lack of opportunity, success, or self-motivation in physical activity. Programs that highlight the use of heart rate monitors offer a…

Tipton, Jan; Sander, Allan N.

2004-01-01

225

Relationship between Exercise Heart Rate and Music Tempo Preference  

ERIC Educational Resources Information Center

The present study examined the predicted positive and linear relationship (Iwanaga, 1995a, 1995b) between exercise heart rate and music tempo preference. Initially, 128 undergraduate students (M age = 20.0 years, SD = 0.9) were surveyed to establish their three favorite music artists. A separate experimental group of 29 undergraduates (M age =…

Karageorghis, Costas I.; Jones, Leighton; Low, Daniel C.

2006-01-01

226

Heart Rate Variability as an Index of Regulated Emotional Responding  

Microsoft Academic Search

The study of individual differences in emotional responding can provide considerable insight into interpersonal dynamics and the etiology of psychopathology. Heart rate variability (HRV) analysis is emerging as an objective measure of regulated emotional responding (generating emotional responses of appropriate timing and magnitude). This review provides a theoretical and empirical rationale for the use of HRV as an index of

Bradley M. Appelhans; Linda J. Luecken

2006-01-01

227

Postprandial Changes of Sympathovagal Balance Measured by Heart Rate Variability  

Microsoft Academic Search

The aim of this study was to investigate thesympathovagal balance after meals by measuring thespectral analysis of heart rate variability (HRV). Ninehealthy volunteers were enrolled in this study. The electrocardiogram (ECG) was recorded for 30 minin a fasting state and 60 min after a 500-kcal testmeal. The HRV was derived from the ECG and was measuredby power spectral analysis using

Ching-Liang Lu; Xiaoping Zou; William C. Orr; J. D. Z. Chen

1999-01-01

228

Heart rate variability is altered following spinal cord injury  

Microsoft Academic Search

Spinal cord injury (SCI) patients are know to suffer from autonomic failure as a result of their injury. The magnitude of the dysautonomia resulting from such an injury is difficult to predict or characterize and, in varying degree, it impedes the recovery of physiological homeostasis. This study is intended to investigate the effectiveness of heart rate variability (HRV) analysis as

David C. Bunten; Alberta L. Warner; Sherry R. Brunnemann; Jack L. Segal

1998-01-01

229

Depression, Heart Rate Variability, and Acute Myocardial Infarction  

Microsoft Academic Search

Background—Clinical depression is associated with an increased risk for mortality in patients with a recent myocardial infarction (MI). Reduced heart rate variability (HRV) has been suggested as a possible explanation for this association. The purpose of this study was to determine if depression is associated with reduced HRV in patients with a recent MI. Methods and Results—Three hundred eighty acute

Robert M. Carney; James A. Blumenthal; Phyllis K. Stein; Lana Watkins; Diane Catellier; Lisa F. Berkman; Susan M. Czajkowski; Christopher O'Connor; Peter H. Stone; Kenneth E. Freedland

230

Practical Implementations of Real-Time Heart Rate Variability.  

National Technical Information Service (NTIS)

Heart rate variability (HRV) is a useful, non-invasive indicator of autonomic nervous system responsiveness that can be used to signal the need for life-saving interventions, but to date it has not been possible to use it in real-time (RT). Because HRV re...

A. Sastre

2004-01-01

231

Heart Rate Variability During Early Adaptation to Space  

NASA Technical Reports Server (NTRS)

A recent report hypothesized that episodes of space motion sickness (SMS) were reliably associated with low frequency oscillations (less than 0.03 to less than 0.01 Hz) in heart rate variability. This paper archives a large data set for review of investigators in this field which may facilitate the evaluation of this hypothesis. Continuous recording of Electro-cardiography (ECG) and other measures were made for 6 to 12 hours per day (waking hours) of six Shuttle crewmembers for the first 3 mission days of two separate Shuttle flights. Spectral analyses of heart rate variability during approximately 200 hours of inflight is presented. In addition, nearly 200 hours of data collected on these same individuals during ground tests prior to the mission are presented. The Purpose of this Publication is to document the incidence of low frequency oscillations of heart rate in 4 people exposed to microgravity over a period of five days. In addition, this report contains spectral analyses of heart rate data collected on these same individuals during ground-based mission simulations. By archiving these data in this manner, it is our intention to make this information available to other investigators interested in studying this phenomena.

Toscano, W. B.; Cowings, P. S.

1994-01-01

232

Heart Rate Variability: Effect of Exercise Intensity on Postexercise Response  

ERIC Educational Resources Information Center

The purpose of the present study was to investigate the influence of two exercise intensities (moderate and severe) on heart rate variability (HRV) response in 16 runners 1 hr prior to (-1 hr) and at +1 hr, +24 hr, +48 hr, and +72 hr following each exercise session. Time domain indexes and a high frequency component showed a significant decrease…

James, David V. B.; Munson, Steven C.; Maldonado-Martin, Sara; De Ste Croix, Mark B. A.

2012-01-01

233

Heart Rate Variability and Drawing Impairment in Hypoxemic COPD  

ERIC Educational Resources Information Center

We studied 54 patients with hypoxemic chronic obstructive pulmonary disease (COPD). The Mini Mental State Examination and the Mental Deterioration Battery were used for neuropsychological assessment. Heart rate variability (HRV) was assessed based on 24-h Holter ECG recording. Mann-Whitney test was used to compare HRV parameters of patients…

Incalzi, Raffaele Antonelli; Corsonello, Andrea; Trojano, Luigi; Pedone, Claudio; Acanfora, Domenico; Spada, Aldo; D'Addio, Gianni; Maestri, Roberto; Rengo, Franco; Rengo, Giuseppe

2009-01-01

234

Sub-?W signal power doppler radar heart rate detection  

Microsoft Academic Search

Periodic motion, such as that resulting from cardiopulmonary activity, can be measured by direct-conversion microwave Doppler radar. In such systems, motion is measured as phase modulation and measurement sensitivity is significantly affected by phase noise and amplitude modulation sidebands in the local oscillator. Presented here are experimental results of heart rate measurements under various signal output power conditions, with consideration

Shuhei Yamada; Mingqi Chen; Victor Lubecke

2006-01-01

235

Non-contact heart rate tracking using Doppler radar  

Microsoft Academic Search

Non-contact vital signs monitoring system based on Continuous-wave (CW) Doppler radar has been becoming more and more attractive in the field of health care. CW Doppler radar has been extensively studied to extract respiration and heart rates, which are vital for many medical applications. This paper will introduce a radar signal processing method, which is able to extract respiration and

He Tan; Dengyu Qiao; Ye Li

2012-01-01

236

Basic notions of heart rate variability and its clinical applicability  

Microsoft Academic Search

Autonomic nervous system (ANS) plays an important role in the regulation of the physiological processes of the human organism during normal and pathological conditions. Among the techniques used in its evaluation, the heart rate variability (HRV) has arising as a simple and non-invasive measure of the autonomic impulses, representing one of the most promising quantitative markers of the autonomic balance.

Luiz Carlos; Marques VANDERLEI; Carlos Marcelo PASTRE; Rosângela Akemi HOSHI; Moacir Fernandes de GODOY

2009-01-01

237

Exploring the Relationship between Fetal Heart Rate and Cognition  

ERIC Educational Resources Information Center

A relationship between fetal heart rate (HR) and cognition is explored within the context of infant, child and adult studies where the association is well established. Lack of direct access to the fetus and maturational changes limit research paradigms and response measures for fetal studies. Nevertheless, neural regulation of HR shows a number of…

Kisilevsky, Barbara S.; Hains, Sylvia M. J.

2010-01-01

238

Model reference adaptive control of heart rate during wheelchair ergometry  

Microsoft Academic Search

This study used parametric methods to identify a model of the wheelchair user's heart rate response to changes in physical workload while on a wheelchair dynamometer. A model reference adaptive control (MRAC) algorithm was developed based upon the results of the system identification process. Based upon subject's maximum speed, ten random levels from zero to maximal speed were selected to

Rory A. Cooper; Tianna L. Fletcher-Shaw; Rick N. Robertson

1998-01-01

239

Changes in Heart Rate Variability in Patients under Local Anesthesia  

Microsoft Academic Search

Spectral analysis of Heart Rate Variability (HRV) is widely used for the assessment of cardiovascular autonomic control. Several studies have shown the effect of anesthetic agents on HRV parameters. In this study a systematic approach of HRV analysis has been employed. The effect caused by the ectopic beats on the spectral measurements has been investigated and results are presented. A

K. Shafqat; S. K. Pal; S. Kumari; P. A. Kyriacou

2007-01-01

240

Thermoregulation mediated by conditioned heart-rate changes in pigeons  

Microsoft Academic Search

Pigeons were subjected to an apparent heat (44 °C) or cold (30 °C) load by means of a thermode located next to their thermosensitive spinal cord. They were then able to obtain brief thermonormality (40 °C) spells if they changed their heart-rate by a preset amount above (or below) their baseline heartrate. In the final experiments the animals increased (or

Markus Sieland; Juan D. Delius; Werner Rautenberg; Bärbel May

1981-01-01

241

Heart rate monitoring during training and competition in cyclists  

Microsoft Academic Search

To obtain optimal training effects and avoid overtraining, it is necessary to monitor the intensity of training. In cycling, speed is not an accurate indicator of exercise intensity, and therefore alternatives have to be found to monitor exercise intensity during training and competition. Power output may be the most direct indicator, but heart rate is easier to monitor and measure.

Asker Jeukendrup; Adrie Van Diemen

1998-01-01

242

Heart Rate and Stress in a College Setting  

ERIC Educational Resources Information Center

Conditions producing stress are present in all colleges and universities. In this paper we report on an investigation utilizing heart rate as an indicator of stress in students when participating in activities encountered in a college classroom or laboratory. The activities included presenting an oral report, taking an exam, and participating in a…

Elwess, Nancy L.; Vogt, F. Daniel

2005-01-01

243

Volitional Control of Heart Rate During Exercise Stress.  

ERIC Educational Resources Information Center

Thirty five volunteer college women were divided into three groups to determine if heart rate could be conditioned instrumentally and lowered during exercise stress on the treadmill. The three groups were a) experimental group I, 15 subjects who received instrumental conditioning with visual feedback; b) instrumental group II, 9 subjects who…

LeFevers, Victoria A.

244

Long-term measurement of heart rate in chicken eggs  

Microsoft Academic Search

Taking advantage of acoustocardiogram (ACG), we measured the heart rate (HR) of chick embryos continuously from day 12 until hatching and then investigated the development of HR irregularities (HRI), HR variability (HRV), and the existence of a circadian rhythm in mean HR (MHR). HRI comprised transient bradycardia and tachycardia, which first developed on day 14 and 16 in most embryos,

Ryuichi Akiyama; Akira Matsuhisa; James T Pearson; Hiroshi Tazawa

1999-01-01

245

Heart rate variability and catecholamines during hypoglycemia and orthostasis  

Microsoft Academic Search

The low frequency component of heart rate variability (HRV) is believed to be affected by sympathetic activity, but an evidence for this suggestion remains controversial. This study analyzed association between HRV and plasma catecholamines in response to two distinct conditions activating sympathetic nervous system.Changes in HRV were analysed from ECG recording and plasma norepinephrine and epinephrine levels were measured in

Miroslav Vlcek; Zofia Radikova; Adela Penesova; Richard Kvetnansky; Richard Imrich

2008-01-01

246

Heart Rate Detection from an Electronic Weighing Scale  

Microsoft Academic Search

We propose a novel technique for heart rate detection on a subject that stands on a common electronic weighing scale. The detection relies on sensing force variations related to the blood acceleration in the aorta, works even if wearing footwear, and does not require any sensors attached to the body. We have applied our method to three different weighing scales,

R. Gonzalez-Landaeta; O. Casas; R. Pallas-Areny

2007-01-01

247

Depression, heart rate variability, and exercise training in dialysis patients  

Microsoft Academic Search

Background Functional limitations, altered cardiac autonomic activity, and psychological distress are known disorders in chronic hemodialysis (HD) patients, relating to increased morbidity and mortality. The aim of this study was to examine the influence of an exercise training program on emotional parameters and heart rate variability (HRV) indices, as well as to determine whether emotional stress contributes to autonomic dysfunction

Evangelia Kouidi; Vassilis Karagiannis; Dimitrios Grekas; Apostolos Iakovides; George Kaprinis; Achilleas Tourkantonis; Asterios Deligiannis

2010-01-01

248

Simplified recurrence plots approach on heart rate variability data  

Microsoft Academic Search

Recurrence plot analysis has been applied to heart rate variability (HRV) data to identify hidden rhythms and complex dynamical patterns of fluctuations. Since the autonomic nervous system (ANS) is the primary regulating factor of HRV, derived measures as well as structural and qualitative aspects of these plots may be associated to different states or changes in neural control. A procedural

L. Cimponeriu; A. Bezerianos

1999-01-01

249

Sleep-Wakefulness Determinations from Heart Rate Data.  

National Technical Information Service (NTIS)

During the second year of this research the REM-NREM algorithm developed during the first year of work to separate the sleep cycles on the basis of minute-by-minute heart rate was re-evaluated on new data as was the algorithm for separation and classifica...

P. C. Richardson A. J. Welch M. J. Lisenby T. P. Daubek

1976-01-01

250

Relationship between laboratory-measured variables and heart rate during an ultra-endurance triathlon  

Microsoft Academic Search

The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean?±?s: age 35?±?6 years, height 1.77?±?0.05?m, mass 74.0?±?6.9?kg, ??=??4.75?±?0.42?l?·?min) performed

Paul B Laursen; Wade L Knez; Cecilia M Shing; Robert H Langill; Edward C Rhodes; David G Jenkins

2005-01-01

251

Feature selection using genetic algorithms for fetal heart rate analysis.  

PubMed

The fetal heart rate (FHR) is monitored on a paper strip (cardiotocogram) during labour to assess fetal health. If necessary, clinicians can intervene and assist with a prompt delivery of the baby. Data-driven computerized FHR analysis could help clinicians in the decision-making process. However, selecting the best computerized FHR features that relate to labour outcome is a pressing research problem. The objective of this study is to apply genetic algorithms (GA) as a feature selection method to select the best feature subset from 64 FHR features and to integrate these best features to recognize unfavourable FHR patterns. The GA was trained on 404 cases and tested on 106 cases (both balanced datasets) using three classifiers, respectively. Regularization methods and backward selection were used to optimize the GA. Reasonable classification performance is shown on the testing set for the best feature subset (Cohen's kappa values of 0.45 to 0.49 using different classifiers). This is, to our knowledge, the first time that a feature selection method for FHR analysis has been developed on a database of this size. This study indicates that different FHR features, when integrated, can show good performance in predicting labour outcome. It also gives the importance of each feature, which will be a valuable reference point for further studies. PMID:24854596

Xu, Liang; Redman, Christopher W G; Payne, Stephen J; Georgieva, Antoniya

2014-07-01

252

Heart rate variability analysis during central hypovolemia using wavelet transformation.  

PubMed

Detection of hypovolemia prior to overt hemodynamic decompensation remains an elusive goal in the treatment of critically injured patients in both civilian and combat settings. Monitoring of heart rate variability has been advocated as a potential means to monitor the rapid changes in the physiological state of hemorrhaging patients, with the most popular methods involving calculation of the R-R interval signal's power spectral density (PSD) or use of fractal dimensions (FD). However, the latter method poses technical challenges, while the former is best suited to stationary signals rather than the non-stationary R-R interval. Both approaches are also limited by high inter- and intra-individual variability, a serious issue when applying these indices to the clinical setting. We propose an approach which applies the discrete wavelet transform (DWT) to the R-R interval signal to extract information at both 500 and 125 Hz sampling rates. The utility of machine learning models based on these features were tested in assessing electrocardiogram signals from volunteers subjected to lower body negative pressure induced central hypovolemia as a surrogate of hemorrhage. These machine learning models based on DWT features were compared against those based on the traditional PSD and FD, at both sampling rates and their performance was evaluated based on leave-one-subject-out fold cross-validation. Results demonstrate that the proposed DWT-based model outperforms individual PSD and FD methods as well as the combination of these two traditional methods at both sample rates of 500 Hz (p value <0.0001) and 125 Hz (p value <0.0001) in detecting the degree of hypovolemia. These findings indicate the potential of the proposed DWT approach in monitoring the physiological changes caused by hemorrhage. The speed and relatively low computational costs in deriving these features may make it particularly suited for implementation in portable devices for remote monitoring. PMID:23371800

Ji, Soo-Yeon; Belle, Ashwin; Ward, Kevin R; Ryan, Kathy L; Rickards, Caroline A; Convertino, Victor A; Najarian, Kayvan

2013-06-01

253

A new physiological method for heart rate correction of the QT interval  

Microsoft Academic Search

AIMTo reassess QT interval rate correction.BACKGROUNDThe QT interval is strongly and inversely related to heart rate. To compare QT intervals between different subjects with different heart rates requires the application of a QT interval rate correction formula. To date these formulae have inappropriately assumed a fixed relation between QT interval and heart rate. An alternative method of QT interval rate

P. Davey

1999-01-01

254

Twenty-Four Hour Time Domain Heart Rate Variability and Heart Rate: Relations to Age and Gender Over Nine Decades  

Microsoft Academic Search

Objectives. This study sought to define the effects of age and gender effects on the normal range of time domain heart rate variability (HRV) over nine decades in healthy subjects.Background. Low HRV is considered an independent marker of mortality risk. However, the age-related decline in HRV may limit its predictive value, particularly in the elderly. Delineation of the range of

Ken Umetani; Donald H Singer; Rollin McCraty; Mike Atkinson

1998-01-01

255

Assessment of mental stress in warmblood horses: heart rate variability in comparison to heart rate and selected behavioural parameters  

Microsoft Academic Search

The aim of the study was to investigate whether heart rate variability (HRV) could assess alterations of the autonomic nervous system (ANS) at different levels of excitement. The behavioural and physiological responses of 20 warmblood horses to a challenging ground exercise task were studied. Prior to the experiment, the horses were evaluated at rest and during forward walking (FW). The

T. R. Rietmann; A. E. A. Stuart; P. Bernasconi; M. Stauffacher; J. A. Auer; M. A. Weishaupt

2004-01-01

256

The influence of mean heart rate on measures of heart rate variability as markers of autonomic function: a model study  

Microsoft Academic Search

Some studies have demonstrated that the assessments of autonomic activities from the alterations of heart rate variations (HRVs) after autonomic blockade and during exercise of high intensity by the spectral analysis of HRV seemed inconsistent with actual situation. The inconsistency is probably caused by the contributions of fluctuating magnitudes and mean levels of autonomic activities on HRV having not been

Hung-Wen Chiu; Ti-Ho Wang; Lu-Chou Huang; Han-Wen Tso; Tsair Kao

2003-01-01

257

Association of hyperglycemia with reduced heart rate variability (The Framingham Heart Study)  

Microsoft Academic Search

This study was designed to examine the association of heart rate variability (HRV) with blood glucose levels in a large community-based population. Previous reports have shown HRV to be reduced in diabetics, suggesting the presence of abnormalities in neural regulatory mechanisms. There is scant information about HRV across the spectrum of blood glucose levels in a population-based cohort. One thousand

Jagmeet P Singh; Martin G Larson; Christopher J O’Donnell; Peter F Wilson; Hisako Tsuji; Donald M Lloyd-Jones; Daniel Levy

2000-01-01

258

Impact of Sleep-Disordered Breathing on Heart Rate Turbulence in Heart Failure Patients  

PubMed Central

Background Sleep-disordered breathing (SDB) is associated with adverse outcomes in patients with chronic heart failure (CHF). Additionally, heart rate turbulence (HRT) reflects changes in the sinus cycle length of baroreceptor in response to hemodynamic fluctuations after ventricular premature beat. Recent studies have suggested that HRT as a marker of vagal activity has a predictive value of poor prognosis in CHF patients. However, little is known about the relationship between SDB and HRT in CHF patients. Methods and Results In this study, 75 patients with CHF were enrolled. We simultaneously performed Holter ECG during a 24-hr period and portable sleep monitoring at nighttime, and determined the respiratory disturbance index (RDI), HRT (turbulence onset (TO) and turbulence slope (TS)) during that 24-hr period. These patients were divided into two groups based on the presence of severe SDB: Group A (RDI?30, n?=?17) and Group B (RDI<30, n?=?58). TS was significantly lower in Group A than in Group B across the 24-hr period (nighttime: 3.6±1.1 vs. 6.9±1.3; daytime: 3.7±0.8 vs. 7.0±1.1; all-day: 3.5±0.7 vs. 6.7±0.9% ms/RR, P<0.05, respectively). TO did not differ between the two groups. Furthermore, there was a significant negative correlation between all-day TS and RDI (R?=?–0.257, P?=?0.027). Moreover, in the multiple regression analysis, RDI was an independent factor to determine all-day TS. Conclusions In patients with severe SDB, blunted TS was observed across 24 hours. These results suggest that SDB induce impairment of vagal activity across a 24-hour period and may be associated with poor prognosis in CHF patients.

Yoshihisa, Akiomi; Suzuki, Satoshi; Takiguchi, Mai; Shimizu, Takeshi; Abe, Satoshi; Sato, Takamasa; Yamaki, Takayoshi; Sugimoto, Koichi; Kunii, Hiroyuki; Nakazato, Kazuhiko; Suzuki, Hitoshi; Saitoh, Shu-ichi; Takeishi, Yasuchika

2014-01-01

259

Heart rate analysis in normal subjects of various age groups  

PubMed Central

Background Analysis of heart rate variation (HRV) has become a popular noninvasive tool for assessing the activities of the autonomic nervous system (ANS). HRV analysis is based on the concept that fast fluctuations may specifically reflect changes of sympathetic and vagal activity. It shows that the structure generating the signal is not simply linear, but also involves nonlinear contributions. Linear parameters, Power spectral indice (LF/HF) is calculated with nonlinear indices Poincare plot geometry(SD1,SD2), Approximate Entropy (ApEn), Largest Lyapunov Exponent (LLE) and Detrended Fluctuation Analysis(DFA). The results show that, with aging the heart rate variability decreases. In this work, the ranges of all linear and nonlinear parameters for four age group normal subjects are presented with an accuracy of more than 89%. As a pre-analysis step, the HRV data is tested for nonlinearity using surrogate data analysis and the results exhibited a significant difference in the ApEn, LLE, SD1/SD2 and DFA parameters of the actual data and the surrogate data. Methods The heart rate is analyzed using the various time domain parameters, frequency domain parameter and nonlinear parameters like Poincare geometry, ApEn, LLE and DFA. Results In this work, the different linear and nonlinear parameters evaluated show a particular range for various cardiac abnormalities. And the results of these were subjected to 't' test with more than 89% confidence interval giving excellent 'p' values in all cases. Conclusions Heart rate variability (HRV) signal can be used as a reliable indicator of state of the heart. It becomes less random with the aging(less chaotic). This is evaluated by using various time domain, frequency domain and nonlinear parameters like SD1/SD2, ApEn, LLE ?s and ?l. Different ranges of non-linear parameters for various age groups are presented with 'p' value ? 0.12.

Acharya U, Rajendra; N, Kannathal; Sing, Ong Wai; Ping, Luk Yi; Chua, TjiLeng

2004-01-01

260

Nonlinear Control of Heart Rate Variability in Human Infants  

NASA Astrophysics Data System (ADS)

Nonlinear analyses of infant heart rhythms reveal a marked rise in the complexity of the electrocardiogram with maturation. We find that normal mature infants (gestation >= 35 weeks) have complex and distinctly nonlinear heart rhythms (consistent with recent reports for healthy adults) but that such nonlinearity is lacking in preterm infants (gestation <= 27 weeks) where parasympathetic-sympathetic interaction and function are presumed to be less well developed. Our study further shows that infants with clinical brain death and those treated with atropine exhibit a similar lack of nonlinear feedback control. These three lines of evidence support the hypothesis championed by Goldberger et al. [Goldberger, A. L., Rigney, D. R. & West, B. J. (1990) Sci. Am. 262, 43-49] that autonomic nervous system control underlies the nonlinearity and possible chaos of normal heart rhythms. This report demonstrates the acquisition of nonlinear heart rate dynamics and possible chaos in developing human infants and its loss in brain death and with the administration of atropine. It parallels earlier work documenting changes in the variability of heart rhythms in each of these cases and suggests that nonlinearity may provide additional power in characterizing physiological states.

Sugihara, George; Allan, Walter; Sobel, Daniel; Allan, Kenneth D.

1996-03-01

261

Physical activity is a major contributor to the ultra low frequency components of heart rate variability  

PubMed Central

OBJECTIVE—To investigate the link between changes in level of physical activity and the pattern of heart rate variability during long term ambulatory monitoring.?DESIGN—Heart rate variability was measured simultaneously with a quantitative indicator of muscle activity by electromyography (EMG) in five men and five women while they did activities typical of daily life or while they rested for 2-3 hours. Spectral and cross spectral analyses were performed on both variables with standard fast Fourier transform.?RESULTS—There was a marked reduction in spectral power in the ultra low frequency band (< 0.003 Hz) on going from active to rest conditions for both heart rate variability (men 6187 (1801) v 410 (89) ms2/Hz; women 4056 (1161) v 2094 (801), mean (SEM); p < 0.01) and EMG (p < 0.001). Cross spectral analysis showed a strong positive gain between the EMG and heart rate variability signal that was virtually eliminated in the resting condition (p < 0.01). A sex-by-condition effect (p = 0.06) was noted with a reduction in total spectral power for heart rate variability during rest in men, while it increased slightly in women.?CONCLUSIONS—There is a quantitative link between muscle activation and heart rate variability in the lowest frequency band. Voluntary restriction of physical activity in healthy young subjects caused marked reduction in spectral power in the lowest frequency band which is often used to assess patient prognosis. The findings strongly suggest that studies of ambulatory heart rate variability should always include an indication of physical activity patterns.???Keywords: spectral analysis; electromyography; Holter monitoring; sex effect

Serrador, J; Finlayson, H; Hughson, R

1999-01-01

262

Voluntary Control of Human Heart Rate: Effect on Reaction to Aversive Stimulation: A Replication and Extension.  

National Technical Information Service (NTIS)

In anticipation of receiving painful stimuli, 20 female subjects learned to regulate their heart rate when provided with meter biofeedback and monetary bonuses for heart rate changes and instructions to increase or decrease their rate. Voluntary slowing o...

A. D. Sirota G. E. Schwartz D. Shapiro

1976-01-01

263

General anesthesia suppresses normal heart rate variability in humans  

NASA Astrophysics Data System (ADS)

The human heart normally exhibits robust beat-to-beat heart rate variability (HRV). The loss of this variability is associated with pathology, including disease states such as congestive heart failure (CHF). The effect of general anesthesia on intrinsic HRV is unknown. In this prospective, observational study we enrolled 100 human subjects having elective major surgical procedures under general anesthesia. We recorded continuous heart rate data via continuous electrocardiogram before, during, and after anesthesia, and we assessed HRV of the R-R intervals. We assessed HRV using several common metrics including Detrended Fluctuation Analysis (DFA), Multifractal Analysis, and Multiscale Entropy Analysis. Each of these analyses was done in each of the four clinical phases for each study subject over the course of 24 h: Before anesthesia, during anesthesia, early recovery, and late recovery. On average, we observed a loss of variability on the aforementioned metrics that appeared to correspond to the state of general anesthesia. Following the conclusion of anesthesia, most study subjects appeared to regain their normal HRV, although this did not occur immediately. The resumption of normal HRV was especially delayed on DFA. Qualitatively, the reduction in HRV under anesthesia appears similar to the reduction in HRV observed in CHF. These observations will need to be validated in future studies, and the broader clinical implications of these observations, if any, are unknown.

Matchett, Gerald; Wood, Philip

2014-06-01

264

Post-Exercise Heart Rate Recovery Independently Predicts Mortality Risk in Patients with Chronic Heart Failure  

PubMed Central

Background Post-exercise heart rate recovery (HRR) is an index of parasympathetic function associated with clinical outcomes in populations with and without documented coronary heart disease. Decreased parasympathetic activity is thought to be associated with disease progression in chronic heart failure (HF), but an independent association between post-exercise HRR and clinical outcomes among such patients has not been established. Methods and Results We measured HRR (calculated as the difference between heart rate at peak exercise and after 1 minute of recovery) in 202 HF subjects and recorded 17 mortality and 15 urgent transplantation outcome events over 624 days of follow-up. Reduced post-exercise HRR was independently associated with increased event risk after adjusting for other exercise-derived variables (peak oxygen uptake and VE/VCO2 slope), for the Heart Failure Survival Score (adjusted HR 1.09 for one beat/min reduction, 95% CI 1.05-1.13, p<0.0001) and the Seattle Heart Failure Model score (adjusted HR 1.08 for one beat/min reduction, 95% CI 1.05-1.12, p<0.0001). Subjects in the lowest risk tertile based on post-exercise HRR (?30 beats/min) had low risk of events irrespective of the risk predicted by the survival scores. In a subgroup of 15 subjects, reduced post-exercise HRR was associated with increased serum markers of inflammation (interleukin-6 r=0.58, p=0.024, high sensitivity C-reactive protein r=0.66, p=0.007). Conclusions Post-exercise HRR predicts mortality risk in patients with HF and provides prognostic information independent of previously described survival models. Pathophysiologic links between autonomic function and inflammation may be mediators of this association.

Tang, Yi-Da; Dewland, Thomas A.; Wencker, Detlef; Katz, Stuart D.

2009-01-01

265

The predictive value of low heart rate and heart rate variability during stress for reoffending in delinquent male adolescents.  

PubMed

Low autonomic (re)activity is a consistent correlate of antisocial behavior in juveniles. However, longitudinal research relating autonomic measures to persistent antisocial behavior has remained scarce. Therefore, in the present study we examined the predictive value of heart rate (HR) and heart rate variability (HRV, often studied as respiratory sinus arrhythmia) for reoffending in delinquent male adolescents. At initial assessment, HR and HRV were measured at rest and in response to a public speaking task. Registered reoffending was assessed after 5-year follow-up. Attenuated HR response and stronger HRV response to stress predicted higher reoffending rates. Results provide evidence that HR/HRV reactivity are neurobiological markers for persistent juvenile antisocial behavior. Although effect sizes were small to moderate, our findings underscore the consistency of the relationship between autonomic markers and antisocial behavior. PMID:21824152

De Vries-Bouw, Marjan; Popma, Arne; Vermeiren, Robert; Doreleijers, Theo A H; Van De Ven, Peter M; Jansen, Lucres M C

2011-11-01

266

Effects of spironolactone on heart rate variability and left ventricular systolic function in severe ischemic heart failure  

Microsoft Academic Search

Recent data show that blockade of aldosterone receptors by spironolactone reduces the risk of morbidity and death among patients with severe heart failure. Heart failure secondary to ischemia is characterized by an imbalance of the autonomic nervous system, which can be assessed by analysis of the heart rate variability (HRV). Spironolactone’s effects on HRV are not well defined. If spironolactone

Mehmet Emin Korkmaz; Haldun Müderriso?lu; Melek Uluçam; Bülent Özin

2000-01-01

267

Analysis of long term heart rate variability: methods, 1/f scaling and implications  

NASA Technical Reports Server (NTRS)

The use of spectral techniques to quantify short term heart rate fluctuations on the order of seconds to minutes has helped define the autonomic contributions to beat-to-beat control of heart rate. We used similar techniques to quantify the entire spectrum (0.00003-1.0 Hz) of heart rate variability during 24 hour ambulatory ECG monitoring. The ECG from standard Holter monitor recordings from normal subjects was sampled with the use of a phase locked loop, and a heart rate time series was constructed at 3 Hz. Frequency analysis of the heart rate signal was performed after a nonlinear filtering algorithm was used to eliminate artifacts. A power spectrum of the entire 24 hour record revealed power that was inversely proportional to frequency, 1/f, over 4 decades from 0.00003 to 0.1 Hz (period approximately 10 hours to 10 seconds). Displaying consecutive spectra calculated at 5 minute intervals revealed marked variability in the peaks at all frequencies throughout the 24 hours, probably accounting for the lack of distinct peaks in the spectra of the entire records.

Saul, J. P.; Albrecht, P.; Berger, R. D.; Cohen, R. J.

1988-01-01

268

Longitudinal monitoring of power output and heart rate profiles in elite cyclists  

Microsoft Academic Search

Power output and heart rate were monitored for 11 months in one female ([Vdot]O2max: 71.5 mL · kg · min) and ten male ([Vdot]O2max: 66.5 ± 7.1 mL · kg · min) cyclists using SRM power-meters to quantify power output and heart rate distributions in an attempt to assess exercise intensity and to relate training variables to performance. In total, 1802 data sets were divided into workout categories according to

Alfred Nimmerichter; Roger G. Eston; Norbert Bachl; Craig Williams

2011-01-01

269

Multifractal heart rate dynamics in human cardiovascular model  

NASA Astrophysics Data System (ADS)

Human cardiovascular and/or cardio-respiratory systems are shown to exhibit both multifractal and synchronous dynamics, and we recently developed a nonlinear, physiologically plausible model for the synchronization between heartbeat and respiration (Kotani, et al. Phys. Rev. E 65: 051923, 2002). By using the same model, we now show the multifractality in the heart rate dynamics. We find that beat-to-beat monofractal noise (fractional Brownian motion) added to the brain stem cardiovascular areas results in significantly broader singularity spectra for heart rate through interactions between sympathetic and parasympathetic nervous systems. We conclude that the model proposed here would be useful in studying the complex cardiovascular and/or cardio- respiratory dynamics in humans.

Kotani, Kiyoshi; Takamasu, Kiyoshi; Safonov, Leonid; Yamamoto, Yoshiharu

2003-05-01

270

Respiration and heart rate in exercising land crabs.  

PubMed

Land Crabs, Cardisoma guanhumi, were fitted with respiratory masks and E.C.G. electrodes and run for 10 or 20 min on a treadmill at speeds of 150 and 300 cm/min. Aerobic metabolism increased linearly with the speed of locomotion. The recovery period was characterized by a large oxygen debt. The primary respiratory adjustment to exercise was an increased ventilation volume; only a minor increase in oxygen extraction occurred. The respiratory exchange ratio increased during exercise and during recovery, presumably correlated with a metabolic acidosis. These results are similar to data collected for exercising vertebrates and the net cost of locomotion of crabs appears similar to quadrupeds. However, the heart rate in exercising crabs changed in an unexpected way: during moderate exercise no change was noted, but during heavy exercise a bradycardia developed. The reduction in rate resulted from an increase in interbeat interval and frequent pauses in the heart beat. PMID:451370

Herreid, C F; Lee, L W; Shah, G M

1979-05-01

271

Electroencephalogram and Heart Rate Measures of Working Memory at 5 and 10 Months of Age  

ERIC Educational Resources Information Center

We recorded electroencephalogram (EEG; 6-9 Hz) and heart rate (HR) from infants at 5 and 10 months of age during baseline and performance on the looking A-not-B task of infant working memory (WM). Longitudinal baseline-to-task comparisons revealed WM-related increases in EEG power (all electrodes) and EEG coherence (medial frontal-occipital…

Cuevas, Kimberly; Bell, Martha Ann; Marcovitch, Stuart; Calkins, Susan D.

2012-01-01

272

Differences in maximum heart rates in distance runners during training, competition and laboratory testing  

Microsoft Academic Search

Successful performance in aerobic distance running is dependant on the athlete's ability to cover a fixed distance in the shortest time possible. An effective distance runner's programme must include an exercise prescription specifically developed for the individual athlete. In this regard, a percentage of either measured or predicted maximum heart rate is commonly used to prescribe and measure exercise intensity.

Ina Shaw

2010-01-01

273

Relation between heart rate variability and training load in middle-distance runners  

Microsoft Academic Search

V. PICHOT, F. ROCHE, J. M. GASPOZ, F. ENJOLRAS, A. ANTONIADIS, P. MININI, F. COSTES, T. BUSSO, J. R. LACOUR, and J. C. BARTHELEMY. Relation between heart rate variability and training load in middle-distance runners. Med. Sci. Sports Exerc., Vol. 32, No. 10, pp. 1729-1736, 2000. Purpose: Monitoring physical performance is of major importance in competitive sports. Indices commonly used,

Vincent PICHOT; Jean-Michel GASPOZ; Franck ENJOLRAS; Anestis ANTONIADIS; Pascal MININI; Thierry BUSSO

2000-01-01

274

Heart rate variability related to effort at work.  

PubMed

Changes in autonomic nervous system function have been related to work stress induced increases in cardiovascular morbidity and mortality. Our purpose was to examine whether various heart rate variability (HRV) measures and new HRV-based relaxation measures are related to self-reported chronic work stress and daily emotions. The relaxation measures are based on neural network modelling of individual baseline heart rate and HRV information. Nineteen healthy hospital workers were studied during two work days during the same work period. Daytime, work time and night time heart rate, as well as physical activity were recorded. An effort-reward imbalance (ERI) questionnaire was used to assess chronic work stress. The emotions of stress, irritation and satisfaction were assessed six times during both days. Seventeen subjects had an ERI ratio over 1, indicating imbalance between effort and reward, that is, chronic work stress. Of the daily emotions, satisfaction was the predominant emotion. The daytime relaxation percentage was higher on Day 2 than on Day 1 (4 ± 6% vs. 2 ± 3%, p < 0.05) and the night time relaxation (43 ± 30%) was significantly higher than daytime or work time relaxation on the both Days. Chronic work stress correlated with the vagal activity index of HRV. However, effort at work had many HRV correlates: the higher the work effort the lower daytime HRV and relaxation time. Emotions at work were also correlated with work time (stress and satisfaction) and night time (irritation) HRV. These results indicate that daily emotions at work and chronic work stress, especially effort, is associated with cardiac autonomic function. Neural network modelling of individual heart rate and HRV information may provide additional information in stress research in field conditions. PMID:21356531

Uusitalo, Arja; Mets, Terhi; Martinmäki, Kaisu; Mauno, Saija; Kinnunen, Ulla; Rusko, Heikki

2011-11-01

275

Nonintrusive measurement of heart rate using a flexible sensor array  

Microsoft Academic Search

Wide interest in wearable technology has brought progresses in wrist-worn, nonintrusive bio-signal measurement techniques. However, previous wrist-worn devices have rigid form-factors, causing them to be vulnerable to motion artifacts. In this paper, we propose a wrist-worn, nonintrusive heart rate sensing module which has an array of sensors mounted on a flexible band. Its flexibility allows it to fit users with

Young Sung Kim; Bae Sun Kim; Yong Ki Son; Il Yeon Cho

2012-01-01

276

Heart rate dynamics in iNOS knockout mice  

Microsoft Academic Search

Nitric oxide has both an inhibitory and excitatory role in the regulation of pre-ganglionic sympathetic neurons, involving the iNOS and nNOS systems respectively. The aim of the present study was to examine cardiovascular autonomic activity in iNOS knockout mice using spectral analysis of heart rate variability (HRV), and to determine the role of iNOS in altered HRV in endotoxaemia. Electrocardiograms

Ali R. Mani; Richard Ollosson; Yasaman Mani; Silvia Ippolito; Kevin P. Moore

2006-01-01

277

Wavelet decomposition analysis of heart rate variability in aerobic athletes  

Microsoft Academic Search

Heart rate variability (HRV) can be quantified, among others, in the frequency domain using digital signal processing (DSP) techniques. The wavelet transform is an alternative tool for the analysis of non-stationary signals. The implementation of perfect reconstruction digital filter banks leads to multi resolution wavelet analysis. Software was developed in LabVIEW.In this study, the average power was compared at each

Dieter Verlinde; Frank Beckers; Dirk Ramaekers; André E. Aubert

2001-01-01

278

Prognostic Significance of PVCs and Resting Heart Rate  

Microsoft Academic Search

Background: We sought to evaluate the prognostic significance of premature ventricular contractions (PVCs) on a routine electrocardiogram (ECG) and to evaluate the relationship between heart rate and PVCs. Methods: Computerized 12-lead ECGs of 45,402 veterans were analyzed. Vital status was available through the California Health Department Service. Results: There were 1731 patients with PVCs (3.8%). Compared to patients without PVCs,

Gregory Engel; Shaun Cho; Afshin Ghayoumi; Takuya Yamazaki; Sung Chun; William F. Fearon; Victor F. Froelicher

2007-01-01

279

Cholesterol enhances classical conditioning of the rabbit heart rate response  

PubMed Central

The cholesterol-fed rabbit is a model of atherosclerosis and has been proposed as an animal model of Alzheimer's disease. Feeding rabbits cholesterol has been shown to increase the number of beta amyloid immunoreactive neurons in the cortex. Addition of copper to the drinking water of cholesterol-fed rabbits can increase this number still further and may lead to plaque-like structures. Classical conditioning of the nictitating membrane response in cholesterol-fed rabbits is retarded in the presence of these plaque-like structures but may be facilitated in their absence. In a factorial design, rabbits fed 2% cholesterol or a normal diet (0% cholesterol) for 8 weeks with or without copper added to the drinking water were given trace classical conditioning using a tone and periorbital electrodermal stimulation to study the effects of cholesterol and copper on classical conditioning of heart rate and the nictitating membrane response. Cholesterol-fed rabbits showed significant facilitation of heart rate conditioning and conditioning-specific modification of heart rate relative to normal diet controls. Consistent with previous research, cholesterol had minimal effects on classical conditioning of the nictitating membrane response when periorbital electrodermal stimulation was used as the unconditioned stimulus. Immunohistochemical analysis showed a significant increase in the number of beta amyloid positive neurons in the cortex, hippocampus and amygdala of the cholesterol-fed rabbits. Supplementation of drinking water with copper increased the number of beta amyloid positive neurons in the cortex of cholesterol-fed rabbits but did not produce plaque-like structures or have a significant effect on heart rate conditioning. The data provide additional support for our finding that, in the absence of plaques, dietary cholesterol may facilitate learning and memory.

Schreurs, Bernard G.; Smith-Bell, Carrie A.; Darwish, Deya S.; Wang, Desheng; Burhans, Lauren B.; Gonzales-Joekes, Jimena; Deci, Stephen; Stankovic, Goran; Sparks, D. Larry

2007-01-01

280

Capturing Entertainment Through Heart Rate Dynamics in the Playware Playground  

Microsoft Academic Search

This paper introduces a statistical approach for capturing enter-tainment in real-time through physiological signals within\\u000a interactive playgrounds inspired by computer games. For this purpose children’s heart rate (HR) signals and judgement on entertainment\\u000a are obtained from experiments on the innovative Playware playground. A comprehensive statistical analysis shows that children’s\\u000a notion of entertainment correlates highly with their average HR during the

Georgios N. Yannakakis; John Hallam; Henrik Hautop Lund

2006-01-01

281

Heart rate variability in children with neurocardiogenic syncope  

Microsoft Academic Search

In order to characterize the autonomic profile of syncopal children, we have studied heart rate variability (HRV) of 73 children, ages 11–18, with neurocardiogenic syncope and a positive outcome of head-up tilt testing (HUT).HRV was calculated over a 24-hour period for the time-domain indices (SDNN, SDANNi, SDNN, rMSSD, pNN50), and over 5-minute segments from night and day for frequency-domain indices

Agnieszka Zygmunt; Jerzy Stanczyk

2004-01-01

282

Estimating mental fatigue based on electroencephalogram and heart rate variability  

NASA Astrophysics Data System (ADS)

The effects of long term mental arithmetic task on psychology are investigated by subjective self-reporting measures and action performance test. Based on electroencephalogram (EEG) and heart rate variability (HRV), the impacts of prolonged cognitive activity on central nervous system and autonomic nervous system are observed and analyzed. Wavelet packet parameters of EEG and power spectral indices of HRV are combined to estimate the change of mental fatigue. Then wavelet packet parameters of EEG which change significantly are extracted as the features of brain activity in different mental fatigue state, support vector machine (SVM) algorithm is applied to differentiate two mental fatigue states. The experimental results show that long term mental arithmetic task induces the mental fatigue. The wavelet packet parameters of EEG and power spectral indices of HRV are strongly correlated with mental fatigue. The predominant activity of autonomic nervous system of subjects turns to the sympathetic activity from parasympathetic activity after the task. Moreover, the slow waves of EEG increase, the fast waves of EEG and the degree of disorder of brain decrease compared with the pre-task. The SVM algorithm can effectively differentiate two mental fatigue states, which achieves the maximum classification accuracy (91%). The SVM algorithm could be a promising tool for the evaluation of mental fatigue. Fatigue, especially mental fatigue, is a common phenomenon in modern life, is a persistent occupational hazard for professional. Mental fatigue is usually accompanied with a sense of weariness, reduced alertness, and reduced mental performance, which would lead the accidents in life, decrease productivity in workplace and harm the health. Therefore, the evaluation of mental fatigue is important for the occupational risk protection, productivity, and occupational health.

Zhang, Chong; Yu, Xiaolin

2010-01-01

283

320-detector row CT coronary angiography: effects of heart rate and heart rate variability on image quality, diagnostic accuracy and radiation exposure  

PubMed Central

Objectives To evaluate the effects of heart rate and heart rate variability on image quality, patient dose and diagnostic accuracy of 320-detector row CT. Methods 94 patients were prospectively enrolled. Heart rate was defined as the mean value of different intervals elapsing between two consecutive R waves in an electrocardiogram (R–R intervals) and the heart rate variability was calculated as the standard deviation from the average heart rate. The image quality was evaluated by four grades, according to motion artefacts (“step artefacts” and “blurring artefacts”). The diagnostic accuracy was analysed in 43 patients who were scheduled for invasive coronary angiography (ICA). The coeffects of heart rate and heart rate variability on image quality, radiation dose and diagnostic accuracy were evaluated by multivariate regression. Results The mean image quality score was 1.2±0.5 and the mean effective dose was 14.8±9.8 mSv. The results showed that heart rate (74.0±11.2 beats per minute) was the single factor influencing image quality (p<0.001) and radiation dose (p<0.001), while heart rate variability (3.7±4.6) had no significant effect on them (p=0.16 and p=0.47, respectively). For 43 patients who underwent ICA, heart rate and heart rate variability showed no influence on the accuracy (p=0.17 and p=0.12, respectively). Overall sensitivity was 97.4% (37/38), specificity was 99.4% (351/353), positive predictive value was 94.9% (37/39) and negative predictive value was 99.7% (351/352). Conclusion 320-detector row CT, with improved longitudinal coverage of detector, resolves step artefact and high patient dose caused by irregular heart rate. However, it is still recommended to control heart rate to a lower level to eliminate blurring artefact and radiation dose.

Sun, G; Li, M; Jiang, X-S; Li, L; Peng, Z-H; Li, G-Y; Xu, L

2012-01-01

284

Heart-rate reactivity to cold pressor stress following biofeedback training  

Microsoft Academic Search

Three previous studies have shown that biofeedback training is useful in modifying heart-rate and pain ratings during ice water stimulation (cold pressor test). Subjects were given an initial cold pressor followed by heart-rate biofeedback training and a final cold pressor test in which they were instructed to control their heart rate in accordance with the prior training. It was assumed

John L. Reeves; David Shapiro

1983-01-01

285

QT intervals and heart rate variability in hypertensive patients.  

PubMed

Low heart rate variability and increased QT dispersion are risk factors for cardiac mortality in various patient populations. We studied dispersion of QT interval, i.e. an index of inhomogeneity of repolarization, and heart rate variability (HRV) i.e., a measure of cardiac autonomic modulation in 76 essential hypertension cases (45 women, 53.0 +/- 11.1 years, body mass index: 25.1 +/- 1.4 kg/m2) and 70 healthy cases (42 women, 54.0 +/- 10.2 years, body mass index: 25.5 +/- 1.6 kg/m2, p > 0.05). QT-corrected QT intervals and their dispersions were significantly higher in the hypertensive group (p < 0.0001), all showing a direct relation with the level of systolic and diastolic blood pressures, ventricular mass index and high Lown grade ventricular rhythm problems. Time domain measures like standard deviation of RR intervals, standard deviation of the means of all corrected RR intervals calculated at 5 min intervals (p < 0.0001), proportion of adjacent RR intervals differing by > 50 msec (p = 0.005), HRV triangular index (p = 0.007), the square root of the mean squared differences of successive RR intervals (p = 0.011), and the high frequency (HF, 0.16-0.40 Hz, p < 0.0001) part of the frequency domain measure of HRV were all decreased, whereas the low frequency (LF, 0.04-0.15 Hz, p = 0.013) part of the frequency domain measures and LF / HF ratio (p < 0.0001) were increased in hypertensive cases. Time domain and the HF part of frequency domain measures of heart rate variability showed an inverse relation with the increased levels of both systolic and diastolic blood pressures and Lown grading system of ventricular rhythm problems, whereas LF and LF / HF showed direct relations with high levels of systolic and diastolic blood pressures and high Lown grade ventricular rhythm problems. The measures of heart rate variability apart from LF and LF / HF were inversely related with the QT intervals and dispersions, whereas LF / HF was directly related with them. Therefore, we conclude that the levels of both systolic and diastolic blood pressures are related to the generation of ventricular rhythm problems either via increasing left ventricular mass which results in an increase in QT parameter measurements, or by altering heart rate variability measures indicating a disturbance in cardiac autonomic balance in essential hypertension. PMID:10850533

Kaftan, A H; Kaftan, O

2000-03-01

286

Unobstrusive heart rate and respiratory rate monitor embedded on a wheelchair  

Microsoft Academic Search

A biomedical system embedded on a wheelchair able to measure heart rate, respiratory rate, and the wheelchair motion state is presented. A wireless multi-channel acquisition module is connected to a BCG (ballistocardiography) unit and to an inertial 3-axial MEMS accelerometer based unit. The sensing units are embedded on the seat and backrest of the wheelchair and the acquired data is

Octavian Postolache; Pedro Silva Girão; Joaquim Mendes; Gabriela Postolache

2009-01-01

287

Measurement of heart-rate variability: Part 1—Comparative study of heart-rate variability analysis methods  

Microsoft Academic Search

A definition of heart-rate variability (h.r.v.) is given. The use of h.r.v. measurement in both clinical applications and\\u000a the neural cardiovascular research is discussed. For the latter applications, four different signals describing h.r.v. are\\u000a reviewed. It is shown that these signals are based on modifications of one model, namely the integral pulse frequency modulator.\\u000a In Part 2, a hardware device

O. Rompelman; A. J. R. M. Coenen; R. I. Kitney

1977-01-01

288

Acute exposure to environmental tobacco smoke and heart rate variability.  

PubMed Central

Environmental tobacco smoke (ETS) has been associated with cardiovascular mortality. Pathophysiologic pathways leading from ETS exposure to cardiopulmonary disease are still being explored. Reduced cardiac autonomic function, as measured by heart rate variability (HRV), has been associated with cardiac vulnerability and may represent an important pathophysiologic mechanism linking ETS and risk of cardiac mortality. In this study we evaluated acute ETS exposure in a commercial airport with changes in HRV in 16 adult nonsmokers. We conducted ambulatory electrocardiographic (ECG) monitoring for 8-hr periods while participants alternated 2 hr in nonsmoking and smoking areas. Nicotine and respirable suspended particle concentrations and participants' blood oxygen saturation were also monitored. We calculated time and frequency domain measures of HRV for periods in and out of the smoking area, and we evaluated associations with ETS using comparative statistics and regression modeling. ETS exposure was negatively associated with all measures of HRV. During exposure periods, we observed an average decrement of approximately 12% in the standard deviation of all normal-to-normal heart beat intervals (an estimate of overall HRV). ETS exposures were not associated with mean heart rate or blood oxygen saturation. Altered cardiac autonomic function, assessed by decrements in HRV, is associated with acute exposure to ETS and may be part of the pathophysiologic mechanisms linking ETS exposure and increased cardiac vulnerability.

Pope, C A; Eatough, D J; Gold, D R; Pang, Y; Nielsen, K R; Nath, P; Verrier, R L; Kanner, R E

2001-01-01

289

Characterizing heart rate variability by scale-dependent Lyapunov exponent  

NASA Astrophysics Data System (ADS)

Previous studies on heart rate variability (HRV) using chaos theory, fractal scaling analysis, and many other methods, while fruitful in many aspects, have produced much confusion in the literature. Especially the issue of whether normal HRV is chaotic or stochastic remains highly controversial. Here, we employ a new multiscale complexity measure, the scale-dependent Lyapunov exponent (SDLE), to characterize HRV. SDLE has been shown to readily characterize major models of complex time series including deterministic chaos, noisy chaos, stochastic oscillations, random 1/f processes, random Levy processes, and complex time series with multiple scaling behaviors. Here we use SDLE to characterize the relative importance of nonlinear, chaotic, and stochastic dynamics in HRV of healthy, congestive heart failure, and atrial fibrillation subjects. We show that while HRV data of all these three types are mostly stochastic, the stochasticity is different among the three groups.

Hu, Jing; Gao, Jianbo; Tung, Wen-Wen

2009-06-01

290

Reading multifractal spectra: Aging by multifractal analysis of heart rate  

NASA Astrophysics Data System (ADS)

The method of effective reading of multifractal properties is proposed. The method consists in the analysis of a given signal together with the analysis of an integrated signal. A practical way to separate monofractal-type signals from other signals is given. The method is applied to 24-hour ECG recordings of RR-interbeat intervals to assess the effect of aging on autonomic regulation of the heart in healthy adults. Heart rate variability is evaluated by multifractal analysis in the VLF band. A switch from mono- to multifractality is observed between diurnal and nocturnal parts of series in the group of young adults. With aging the multifractal structure of nocturnal signals declines. The observed changes can be related to the circadian alternation in the central mechanisms controlling the cardiovascular system which becomes impaired with advance in age in human. Indices for age impairment of autonomic regulation are proposed.

Makowiec, D.; Rynkiewicz, A.; Ga?aska, R.; Wdowczyk-Szulc, J.; ?arczy?ska-Buchowiecka, M.

2011-06-01

291

Analysis of heart rate variability using fuzzy measure entropy.  

PubMed

This paper proposed a new entropy measure, Fuzzy Measure Entropy (FuzzyMEn), for the analysis of heart rate variability (HRV) signals. FuzzyMEn was calculated based on the fuzzy set theory and improved the poor statistical stability in the approximate entropy (ApEn) and sample entropy (SampEn). The simulation results also demonstrated that the FuzzyMEn had better algorithm discrimination ability when compared with the recently published fuzzy entropy (FuzzyEn), The validity of FuzzyMEn was tested for clinical HRV analysis on 120 subjects (60 heart failure and 60 healthy control subjects). It is concluded that FuzzyMEn could be considered as a valid and reliable method for a clinical HRV application. PMID:23273774

Liu, Chengyu; Li, Ke; Zhao, Lina; Liu, Feng; Zheng, Dingchang; Liu, Changchun; Liu, Shutang

2013-02-01

292

The loss of circadian heart rate variations in patients undergoing mitral valve replacement and Corridor procedure--comparison to heart transplant patients.  

PubMed

We have presently demonstrated that when added to mitral valve replacement (MVR) the corridor procedure is 75% efficient in restoring and maintaining sinus rhythm in patients with chronic atrial fibrillation (AF), caused by rheumatic mitral valve disease, (follow up 13.9months). In the same patient population, we observed that the typical day-night cycle heart rate (HR) variations were lost and our present study concentrates on this subject. Heart rate variability analysis based on 24-h Holter ECG recording (StrataScan 563 DelMar Avionics) or hospital discharge (12th-14th postoperative days) was performed in 3 patient groups: Group I: Patients with a Corridor procedure added to MVR (12pts, m/f 10/2, mean age 47.3+/-7.5yr); Group II (control): with patients MVR performed through the left atrial approach, without additional antiarrhythmic procedures (10pts, m/f 3/7 mean age 51.5+/-6.7yr), and Group III: heart transplant recipients (5pts, mean age 46.4+/-11.22yr). We analyzed the hourly heart rate over 24-h period divided into three 8-h segments (07-14h; 15-22h and 23-06h). Statistical comparison of mean hourly heart rate values was made between the three time periods of Holter monitoring. The Corridor procedure performed with mitral valve replacement resulted in conversion of sinus rhythm in 75% of patients (Group I), but postoperative heart rate variability analyses based on Holter monitoring disclosed that the mean heart rate was not statistically significantly difficult between the three 8-h segments of the day-night (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). In the second group (classical MVR), statistically significant differences in mean HR variation existed between the three 8-h intervals (P<0.05), and although atrial fibrillation occurred postoperatively physiologic circadian heart rate variations were preserved. With the Corridor procedure, both atria were surgically and electrically isolated and chronotropic function of the ventricles was restored by creating a small strip of atrial tissue with isolated sinus node and atrio-ventricular node, connected to the ventricles. This technique produced heart denervation nervous system influence, producing the loss of circadian HR variations, similar to the transplanted heart. PMID:11137811

Velimirovic, D B; Pavlovic, S U; Petrovic, P; Neskovic, A; Zivkovic, M; Bojic, M

2001-02-01

293

The effects of cold-water immersion on power output and heart rate in elite cyclists.  

PubMed

The purpose of this study was to examine the effects of cold-water immersion on power output, heart rate, and time to peak power in 10 well-trained cyclists. The Compu-trainer Professional Model 8001 computerized stationary trainer was used to evaluate maximum power, average power, and time to peak power during a simulated cycling sprint. The heart rate was measured using a Polar heart rate monitor. Subjects performed 2 maximum-effort sprints (for approximately 30 seconds) separated by either an experimental condition (15 minutes of cold-water immersion at 12 degrees C up to the level of the iliac crest) or a control condition (15 minutes of quiet sitting). All subjects participated under both control and experimental conditions in a counterbalanced design in which 5 subjects performed the experimental condition first and the other 5 subjects performed the control condition first. Each condition was separated by at least 2 days. The time to peak power was not different between the 2 conditions. Maximum and average powers declined by 13.7 and 9.5% for the experimental condition but only by 4.7 and 2.3% for the control condition, respectively. The results also demonstrated a significantly greater decline in maximum heart rate after cold-water immersion (8.1%) than under the control condition (2.4%). Average heart rate showed a decrease of 4.2% under the experimental condition, as compared with an increase of 1.5% under the control condition. The major findings of this study suggest that a relatively brief period of cold-water immersion can manifest significant physiological effects that can impair cycling performance. PMID:12423186

Schniepp, Jason; Campbell, Teri S; Powell, Kasey L; Pincivero, Danny M

2002-11-01

294

Heart rate variability in overactive bladder experimental model  

PubMed Central

Introduction Two main pathophysiological concepts of overactive bladder (OAB) are postulated: the neurogenic and myogenic theories. Autonomic nervous system (ANS) dysfunction is also involved in OAB pathophysiology. The purpose of our study was to estimate ANS activity by heart rate variability (HRV) assessment in two OAB experimental models evoked by cyclophosphamide administration: acute (AOAB) and chronic (COAB) overactive ones. Material and methods In the AOAB model, an i.p. dose of cyclophosphamide was administered (200 mg/kg body weight) while the COAB model received 4 times the i.p. administration of cyclophosphamide (75 mg/kg body weight). In each subject, after urethane anaesthesia (1.2 g/kg body weight), 20-minute ECG recordings (PowerLab) were performed with subsequent HRV analysis. Results Most of the differences in time domain analysis parameters were insignificant, except those concerning SDNN and rMSSD (p < 0.05). In frequency analysis, a power decrease of all standard spectral components was revealed in both OAB groups. In AOAB, TP (1.43 ±1.21 vs. 7.92 ±6.22 in control; p < 0.05) and VLF (0.95 ±1.08 vs. 6.97 ±5.99 in control; p < 0.05) showed significant power decrease, whereas the COAB group was mostly characterized by LF (0.09 ±0.15 vs. 0.34 ±0.33 in control; p < 0.05) and HF (0.25 ±0.29 vs. 0.60 ±0.41 in control; p < 0.05) decrease. Conclusions The ANS disturbances, found as standard spectral parameter abnormalities, were demonstrated in both AOAB and COAB. When this finding is analysed, together with the lack of statistically significant differences in normalized nLF and nHF powers, the VLF changes seem to play an essential role, probably reflecting the progression in bladder inflammatory changes.

Thor, Piotr

2012-01-01

295

Genetic locus on mouse chromosome 7 controls elevated heart rate  

PubMed Central

Elevated heart rate (HR) is a risk factor for cardiovascular diseases. The goal of the study was to map HR trait in mice using quantitative trait locus (QTL) analysis followed by genome-wide association (GWA) analysis. The first approach provides mapping power and the second increases genome resolution. QTL analyses were performed in a C3HeB×SJL backcross. HR and systolic blood pressure (SBP) were measured by the tail-cuff plethysmography. HR was ?80 beats/min higher in SJL compared with C3HeB. There was a wide distribution of the HR (536–763 beats/min) in N2 mice. We discovered a highly significant QTL (logarithm of odds = 6.7, P < 0.001) on chromosome 7 (41 cM) for HR in the C3HeB×SJL backcross. In the Hybrid Mouse Diversity Panel (58 strains, n = 5–6/strain) we found that HR (beats/min) ranged from 546 ± 12 in C58/J to 717 ± 7 in MA/MyJ mice. SBP (mmHg) ranged from 99 ± 6 in strain I/LnJ to 151 ± 4 in strain BXA4/PgnJ. GWA analyses were done using the HMDP, which revealed a locus (64.2–65.1 Mb) on chromosome 7 that colocalized with the QTL for elevated HR found in the C3HeB×SJL backcross. The peak association was observed for 17 SNPs that are localized within three GABAA receptor genes. In summary, we used a combined genetic approach to fine map a novel elevated HR locus on mouse chromosome 7.

Smolock, Elaine M.; Ilyushkina, Irina A.; Ghazalpour, Anatole; Gerloff, Janice; Murashev, Arkady N.; Lusis, Aldons J.

2012-01-01

296

Heart rate variability and disease characteristics in patients with COPD.  

PubMed

Heart rate variability (HRV) is reduced in patients with chronic obstructive pulmonary disease (COPD). However, the relationships among HRV and characteristics of COPD are unknown. The aim of this study was to characterize HRV in patients with COPD and to verify the correlation of HRV measured during rest with disease severity and pulmonary, muscular, and functional impairment. Thirty-one patients with COPD (16 male; 66 +/- 8 years; BMI = 24 +/- 6 kg/m(2); FEV(1) = 46 +/- 16% predicted) without severe cardiac dysfunction were included. HRV assessment was performed by the head-up tilt test (HUTT), and the main variables used for analysis were SDNN index, LF/HF ratio, and R-R intervals. Other tests included spirometry, bioelectrical impedance, cardiopulmonary exercise test, 6-minute walk test, respiratory and peripheral muscle force, health-related quality of life and functional status questionnaires, and objective quantification of physical activity level in daily life with the DynaPort and SenseWear armband activity monitors, besides calculation of the BODE index. There was a statistical difference in all variables of HRV between the HUTT positions (lying and standing). There was no correlation of HRV with BODE index or FEV(1). Out of the BODE index, just the BMI was correlated with SDNN and R-R intervals (r = 0.44; p < 0.05 and r = 0.37; p < 0.05, respectively). There was correlation between HRV reduction and a lower level of physical activity in daily life, besides worse health-related quality of life, functional status, and respiratory and peripheral muscle force. Cardiac autonomic function of patients with COPD is not related to disease severity but mainly to the level of physical activity in daily life. PMID:18815834

Camillo, Carlos A; Pitta, Fabio; Possani, Heloíse V; Barbosa, Marcus V R A; Marques, Divina S O; Cavalheri, Vinícius; Probst, Vanessa S; Brunetto, Antonio F

2008-01-01

297

Muscle metaboreflex and autonomic regulation of heart rate in humans.  

PubMed

We elucidated the autonomic mechanisms whereby heart rate (HR) is regulated by the muscle metaboreflex. Eight male participants (22 ± 3 years) performed three exercise protocols: (1) enhanced metaboreflex activation with partial flow restriction (bi-lateral thigh cuff inflation) during leg cycling exercise, (2) isolated muscle metaboreflex activation (post-exercise ischaemia; PEI) following leg cycling exercise, (3) isometric handgrip followed by PEI. Trials were undertaken under control (no drug), ?1-adrenergic blockade (metoprolol) and parasympathetic blockade (glycopyrrolate) conditions. HR increased with partial flow restriction during leg cycling in the control condition (11 ± 2 beats min(-1); P < 0.05). The magnitude of this increase in HR was similar with parasympathetic blockade (11 ± 2 beats min(-1)), but attenuated with ?-adrenergic blockade (4 ± 1 beats min(-1); P < 0.05 vs. control and parasympathetic blockade). During PEI following leg cycling exercise, HR remained similarly elevated above rest under all conditions (11 ± 2, 13 ± 3 and 9 ± 4 beats min(-1), for control, ?-adrenergic and parasympathetic blockade; P > 0.05 between conditions). During PEI following handgrip, HR was similarly elevated from rest under control and parasympathetic blockade (4 ± 1 vs. 4 ± 2 beats min(-1); P > 0.05 between conditions) conditions, but attenuated with ?-adrenergic blockade (0.2 ± 1 beats min(-1); P > 0.05 vs. rest). Thus muscle metaboreflex activation-mediated increases in HR are principally attributable to increased cardiac sympathetic activity, and only following exercise with a large muscle mass (PEI following leg cycling) is there a contribution from the partial withdrawal of cardiac parasympathetic tone. PMID:23713032

Fisher, James P; Adlan, Ahmed M; Shantsila, Alena; Secher, J Frederik; Sørensen, Henrik; Secher, Niels H

2013-08-01

298

Heart Rate Variability in Men with Erectile dysfunction  

PubMed Central

Purpose The objective of this study is to investigate alteration of autonomic nervous system (ANS) activity in patients suffering from erectile dysfunction (ED) by comparing parameters of heart rate variability (HRV) between men with ED and healthy subjects. Methods A retrospective review was performed on 40 ED patients (mean age, 46.0±8.49 years) without any disease and 180 healthy control people (mean age, 44.4±7.83 years) without ED in our institution from June 2008 to July 2010. And electrocardiographic signals were obtained to measure HRV parameters for both patients and controls in a resting state. Results For the time domain analysis, square root of the mean differences between successive RR intervals (RMSSD) representing parasympathetic activity was lower in patients than controls although P-value was not statistically significant (P=0.060). For the frequency domain analysis, high frequency (HF) representing parasympathetic activity was lower in patients than controls (P=0.232) and low frequency (LF) representing mainly sympathetic activity was higher in patients than controls (P=0.416). Lastly, LF/HF ratio reflecting sympathetic/parasympathetic activity ratio was statistically higher in patients than controls (P=0.027). Conclusions Patients with ED exhibited different HRV parameters compared with normal controls. This suggests that the patients with ED may have some kind of imbalance in the ANS and it may be possible that general imbalance of the ANS is one of the causes of ED. Thus, HRV analysis may give valuable diagnostic information and serve as a rapid screening tool to evaluate altered ANS activity in patients with ED.

Lee, Ji Yong; Joo, Kwan-Joong; Kim, Jin Tae; Cho, Sung Tae; Cho, Dae Sung; Won, Yong-Yeun

2011-01-01

299

Heart Rate Lowering by Specific and Selective If Current Inhibition with Ivabradine: A New Therapeutic Perspective in Cardiovascular Disease  

Microsoft Academic Search

and the mortality benefit of some cardiovascular drugs seems to be related in part to their heart rate-lowering effects. Since it is difficult to separate the benefit of heart rate lowering from other actions with currently available drugs, a 'pure' heart rate-lowering drug would be of great interest in establishing the benefit of heart rate reduction per se. Heart rate

Dario DiFrancesco; John A. Camm

2004-01-01

300

Heart rate and arterial blood pressure at the onset of static exercise in man with complete neural blockade.  

PubMed Central

1. We tested the 'muscle-heart reflex' hypothesis for the immediate increases in heart rate and blood pressure at the onset of static exercise in man by performing complete blockade of afferent nerves from the working muscles. Brief (5 s) maximal static hand-grip contractions were performed without performing a Valsalva-like manoeuvre and with no increase in central venous pressure both before and after combined axillary and radial blockade with lidocaine. Muscle strength was reduced to near zero. The effectiveness of the afferent neural blockade was evaluated by recording the heart rate and blood pressure responses and rating the perceived pain during a cold pressor test of the blocked and contralateral unblocked hand. 2. The cold pressor test increased blood pressure but had no effect on heart rate. Afferent neural blockade eliminated the increase in blood pressure and the perceived pain associated with the cold pressor test. Maximal hand-grip contractions resulted in immediate and similar increases in heart rate and blood pressure before and after afferent neural blockade of the arm. 3. The results of this study suggest that the immediate increases in heart rate and blood pressure at the onset of static exercise in man occur when the 'muscle-heart reflex' is inoperable. Images Fig. 1

Friedman, D B; Jensen, F B; Mitchell, J H; Secher, N H

1990-01-01

301

Deceleration capacity of heart rate as a predictor of mortality after myocardial infarction: cohort study  

Microsoft Academic Search

Background Decreased vagal activity after myocardial infarction results in reduced heart-rate variability and increased risk of death. To distinguish between vagal and sympathetic factors that aff ect heart-rate variability, we used a signal- processing algorithm to separately characterise deceleration and acceleration of heart rate. We postulated that diminished deceleration-related modulation of heart rate is an important prognostic marker. Our prospective

Axel Bauer; Jan W Kantelhardt; Petra Barthel; Raphael Schneider; Timo Mäkikallio; Kurt Ulm; Katerina Hnatkova; Albert Schömig; Heikki Huikuri; Armin Bunde; Marek Malik; Georg Schmidt

2006-01-01

302

Resting Heart Rate and Outcomes in Patients with Cardiovascular Disease: Where Do We Currently Stand?  

PubMed Central

Background Data from large epidemiological studies suggest that elevated heart rate is independently associated with cardiovascular and all-cause mortality in patients with hypertension and in those with established cardiovascular disease. Clinical trial findings also suggest that the favorable effects of beta-blockers and other heart rate–lowering agents in patients with acute myocardial infarction and congestive heart failure may be, at least in part, due to their heart rate–lowering effects. Contemporary clinical outcome prediction models such as the Global Registry of Acute Coronary Events (GRACE) score include admission heart rate as an independent risk factor. Aims This article critically reviews the key epidemiology concerning heart rate and cardiovascular risk, potential mechanisms through which an elevated resting heart rate may be disadvantageous and evaluates clinical trial outcomes associated with pharmacological reduction in resting heart rate. Conclusions Prospective randomised data from patients with significant coronary heart disease or heart failure suggest that intervention to reduce heart rate in those with a resting heart rate >70 bpm may reduce cardiovascular risk. Given the established observational data and randomised trial evidence, it now appears appropriate to include reduction of elevated resting heart rate by lifestyle +/? pharmacological therapy as part of a secondary prevention strategy in patients with cardiovascular disease.

Menown, Ian BA; Davies, Simon; Gupta, Sandeep; Kalra, Paul R; Lang, Chim C; Morley, Chris; Padmanabhan, Sandosh

2013-01-01

303

Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders.  

PubMed

Elevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate-increasing and heart rate-decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets. PMID:23583979

den Hoed, Marcel; Eijgelsheim, Mark; Esko, Tõnu; Brundel, Bianca J J M; Peal, David S; Evans, David M; Nolte, Ilja M; Segrè, Ayellet V; Holm, Hilma; Handsaker, Robert E; Westra, Harm-Jan; Johnson, Toby; Isaacs, Aaron; Yang, Jian; Lundby, Alicia; Zhao, Jing Hua; Kim, Young Jin; Go, Min Jin; Almgren, Peter; Bochud, Murielle; Boucher, Gabrielle; Cornelis, Marilyn C; Gudbjartsson, Daniel; Hadley, David; van der Harst, Pim; Hayward, Caroline; den Heijer, Martin; Igl, Wilmar; Jackson, Anne U; Kutalik, Zoltán; Luan, Jian'an; Kemp, John P; Kristiansson, Kati; Ladenvall, Claes; Lorentzon, Mattias; Montasser, May E; Njajou, Omer T; O'Reilly, Paul F; Padmanabhan, Sandosh; St Pourcain, Beate; Rankinen, Tuomo; Salo, Perttu; Tanaka, Toshiko; Timpson, Nicholas J; Vitart, Veronique; Waite, Lindsay; Wheeler, William; Zhang, Weihua; Draisma, Harmen H M; Feitosa, Mary F; Kerr, Kathleen F; Lind, Penelope A; Mihailov, Evelin; Onland-Moret, N Charlotte; Song, Ci; Weedon, Michael N; Xie, Weijia; Yengo, Loic; Absher, Devin; Albert, Christine M; Alonso, Alvaro; Arking, Dan E; de Bakker, Paul I W; Balkau, Beverley; Barlassina, Cristina; Benaglio, Paola; Bis, Joshua C; Bouatia-Naji, Nabila; Brage, Søren; Chanock, Stephen J; Chines, Peter S; Chung, Mina; Darbar, Dawood; Dina, Christian; Dörr, Marcus; Elliott, Paul; Felix, Stephan B; Fischer, Krista; Fuchsberger, Christian; de Geus, Eco J C; Goyette, Philippe; Gudnason, Vilmundur; Harris, Tamara B; Hartikainen, Anna-Liisa; Havulinna, Aki S; Heckbert, Susan R; Hicks, Andrew A; Hofman, Albert; Holewijn, Suzanne; Hoogstra-Berends, Femke; Hottenga, Jouke-Jan; Jensen, Majken K; Johansson, Asa; Junttila, Juhani; Kääb, Stefan; Kanon, Bart; Ketkar, Shamika; Khaw, Kay-Tee; Knowles, Joshua W; Kooner, Angrad S; Kors, Jan A; Kumari, Meena; Milani, Lili; Laiho, Päivi; Lakatta, Edward G; Langenberg, Claudia; Leusink, Maarten; Liu, Yongmei; Luben, Robert N; Lunetta, Kathryn L; Lynch, Stacey N; Markus, Marcello R P; Marques-Vidal, Pedro; Mateo Leach, Irene; McArdle, Wendy L; McCarroll, Steven A; Medland, Sarah E; Miller, Kathryn A; Montgomery, Grant W; Morrison, Alanna C; Müller-Nurasyid, Martina; Navarro, Pau; Nelis, Mari; O'Connell, Jeffrey R; O'Donnell, Christopher J; Ong, Ken K; Newman, Anne B; Peters, Annette; Polasek, Ozren; Pouta, Anneli; Pramstaller, Peter P; Psaty, Bruce M; Rao, Dabeeru C; Ring, Susan M; Rossin, Elizabeth J; Rudan, Diana; Sanna, Serena; Scott, Robert A; Sehmi, Jaban S; Sharp, Stephen; Shin, Jordan T; Singleton, Andrew B; Smith, Albert V; Soranzo, Nicole; Spector, Tim D; Stewart, Chip; Stringham, Heather M; Tarasov, Kirill V; Uitterlinden, André G; Vandenput, Liesbeth; Hwang, Shih-Jen; Whitfield, John B; Wijmenga, Cisca; Wild, Sarah H; Willemsen, Gonneke; Wilson, James F; Witteman, Jacqueline C M; Wong, Andrew; Wong, Quenna; Jamshidi, Yalda; Zitting, Paavo; Boer, Jolanda M A; Boomsma, Dorret I; Borecki, Ingrid B; van Duijn, Cornelia M; Ekelund, Ulf; Forouhi, Nita G; Froguel, Philippe; Hingorani, Aroon; Ingelsson, Erik; Kivimaki, Mika; Kronmal, Richard A; Kuh, Diana; Lind, Lars; Martin, Nicholas G; Oostra, Ben A; Pedersen, Nancy L; Quertermous, Thomas; Rotter, Jerome I; van der Schouw, Yvonne T; Verschuren, W M Monique; Walker, Mark; Albanes, Demetrius; Arnar, David O; Assimes, Themistocles L; Bandinelli, Stefania; Boehnke, Michael; de Boer, Rudolf A; Bouchard, Claude; Caulfield, W L Mark; Chambers, John C; Curhan, Gary; Cusi, Daniele; Eriksson, Johan; Ferrucci, Luigi; van Gilst, Wiek H; Glorioso, Nicola; de Graaf, Jacqueline; Groop, Leif; Gyllensten, Ulf; Hsueh, Wen-Chi; Hu, Frank B; Huikuri, Heikki V; Hunter, David J; Iribarren, Carlos; Isomaa, Bo; Jarvelin, Marjo-Riitta; Jula, Antti; Kähönen, Mika; Kiemeney, Lambertus A; van der Klauw, Melanie M; Kooner, Jaspal S; Kraft, Peter; Iacoviello, Licia; Lehtimäki, Terho; Lokki, Marja-Liisa L; Mitchell, Braxton D; Navis, Gerjan; Nieminen, Markku S; Ohlsson, Claes; Poulter, Neil R; Qi, Lu; Raitakari, Olli T; Rimm, Eric B; Rioux, John D; Rizzi, Federica; Rudan, Igor; Salomaa, Veikko; Sever, Peter S; Shields, Denis C; Shuldiner, Alan R; Sinisalo, Juha; Stanton, Alice V; Stolk, Ronald P; Strachan, David P; Tardif, Jean-Claude; Thorsteinsdottir, Unnur; Tuomilehto, Jaako; van Veldhuisen, Dirk J; Virtamo, Jarmo; Viikari, Jorma; Vollenweider, Peter; Waeber, Gérard; Widen, Elisabeth; Cho, Yoon Shin; Olsen, Jesper V; Visscher, Peter M; Willer, Cristen; Franke, Lude; Erdmann, Jeanette; Thompson, John R; Pfeufer, Arne; Sotoodehnia, Nona; Newton-Cheh, Christopher; Ellinor, Patrick T; Stricker, Bruno H Ch; Metspalu, Andres; Perola, Markus

2013-06-01

304

Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders  

PubMed Central

Elevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate–increasing and heart rate–decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets.

den Hoed, Marcel; Eijgelsheim, Mark; Esko, Tonu; Brundel, Bianca J J M; Peal, David S; Evans, David M; Nolte, Ilja M; Segre, Ayellet V; Holm, Hilma; Handsaker, Robert E; Westra, Harm-Jan; Johnson, Toby; Isaacs, Aaron; Yang, Jian; Lundby, Alicia; Zhao, Jing Hua; Kim, Young Jin; Go, Min Jin; Almgren, Peter; Bochud, Murielle; Boucher, Gabrielle; Cornelis, Marilyn C; Gudbjartsson, Daniel; Hadley, David; Van Der Harst, Pim; Hayward, Caroline; Heijer, Martin Den; Igl, Wilmar; Jackson, Anne U; Kutalik, Zoltan; Luan, Jian'an; Kemp, John P; Kristiansson, Kati; Ladenvall, Claes; Lorentzon, Mattias; Montasser, May E; Njajou, Omer T; O'Reilly, Paul F; Padmanabhan, Sandosh; Pourcain, Beate St.; Rankinen, Tuomo; Salo, Perttu; Tanaka, Toshiko; Timpson, Nicholas J; Vitart, Veronique; Waite, Lindsay; Wheeler, William; Zhang, Weihua; Draisma, Harmen H M; Feitosa, Mary F; Kerr, Kathleen F; Lind, Penelope A; Mihailov, Evelin; Onland-Moret, N Charlotte; Song, Ci; Weedon, Michael N; Xie, Weijia; Yengo, Loic; Absher, Devin; Albert, Christine M; Alonso, Alvaro; Arking, Dan E; de Bakker, Paul I W; Balkau, Beverley; Barlassina, Cristina; Benaglio, Paola; Bis, Joshua C; Bouatia-Naji, Nabila; Brage, S?ren; Chanock, Stephen J; Chines, Peter S; Chung, Mina; Darbar, Dawood; Dina, Christian; Dorr, Marcus; Elliott, Paul; Felix, Stephan B; Fischer, Krista; Fuchsberger, Christian; de Geus, Eco J C; Goyette, Philippe; Gudnason, Vilmundur; Harris, Tamara B; Hartikainen, Anna-liisa; Havulinna, Aki S; Heckbert, Susan R; Hicks, Andrew A; Hofman, Albert; Holewijn, Suzanne; Hoogstra-Berends, Femke; Hottenga, Jouke-Jan; Jensen, Majken K; Johansson, Asa; Junttila, Juhani; Kaab, Stefan; Kanon, Bart; Ketkar, Shamika; Khaw, Kay-Tee; Knowles, Joshua W; Kooner, Angrad S; Kors, Jan A; Kumari, Meena; Milani, Lili; Laiho, Paivi; Lakatta, Edward G; Langenberg, Claudia; Leusink, Maarten; Liu, Yongmei; Luben, Robert N; Lunetta, Kathryn L; Lynch, Stacey N; Markus, Marcello R P; Marques-Vidal, Pedro; Leach, Irene Mateo; McArdle, Wendy L; McCarroll, Steven A; Medland, Sarah E; Miller, Kathryn A; Montgomery, Grant W; Morrison, Alanna C; Muller-Nurasyid, Martina; Navarro, Pau; Nelis, Mari; O'Connell, Jeffrey R; O'Donnell, Christopher J; Ong, Ken K; Newman, Anne B; Peters, Annette; Polasek, Ozren; Pouta, Anneli; Pramstaller, Peter P; Psaty, Bruce M; Rao, Dabeeru C; Ring, Susan M; Rossin, Elizabeth J; Rudan, Diana; Sanna, Serena; Scott, Robert A; Sehmi, Jaban S; Sharp, Stephen; Shin, Jordan T; Singleton, Andrew B; Smith, Albert V; Soranzo, Nicole; Spector, Tim D; Stewart, Chip; Stringham, Heather M; Tarasov, Kirill V; Uitterlinden, Andre G; Vandenput, Liesbeth; Hwang, Shih-Jen; Whitfield, John B; Wijmenga, Cisca; Wild, Sarah H; Willemsen, Gonneke; Wilson, James F; Witteman, Jacqueline C M; Wong, Andrew; Wong, Quenna; Jamshidi, Yalda; Zitting, Paavo; Boer, Jolanda M A; Boomsma, Dorret I; Borecki, Ingrid B; Van Duijn, Cornelia M; Ekelund, Ulf; Forouhi, Nita G; Froguel, Philippe; Hingorani, Aroon; Ingelsson, Erik; Kivimaki, Mika; Kronmal, Richard A; Kuh, Diana; Lind, Lars; Martin, Nicholas G; Oostra, Ben A; Pedersen, Nancy L; Quertermous, Thomas; Rotter, Jerome I; van der Schouw, Yvonne T; Verschuren, W M Monique; Walker, Mark; Albanes, Demetrius; Arnar, David O; Assimes, Themistocles L; Bandinelli, Stefania; Boehnke, Michael; de Boer, Rudolf A; Bouchard, Claude; Caulfield, W L Mark; Chambers, John C; Curhan, Gary; Cusi, Daniele; Eriksson, Johan; Ferrucci, Luigi; van Gilst, Wiek H; Glorioso, Nicola; de Graaf, Jacqueline; Groop, Leif; Gyllensten, Ulf; Hsueh, Wen-Chi; Hu, Frank B; Huikuri, Heikki V; Hunter, David J; Iribarren, Carlos; Isomaa, Bo; Jarvelin, Marjo-Riitta; Jula, Antti; Kahonen, Mika; Kiemeney, Lambertus A; van der Klauw, Melanie M; Kooner, Jaspal S; Kraft, Peter; Iacoviello, Licia; Lehtimaki, Terho; Lokki, Marja-Liisa L; Mitchell, Braxton D; Navis, Gerjan; Nieminen, Markku S; Ohlsson, Claes; Poulter, Neil R; Qi, Lu; Raitakari, Olli T; Rimm, Eric B; Rioux, John D; Rizzi, Federica; Rudan, Igor; Salomaa, Veikko; Sever, Peter S; Shields, Denis C; Shuldiner, Alan R; Sinisalo, Juha; Stanton, Alice V; Stolk, Ronald P; Strachan, David P; Tardif, Jean-Claude; Thorsteinsdottir, Unnur; Tuomilehto, Jaako; van Veldhuisen, Dirk J; Virtamo, Jarmo; Viikari, Jorma; Vollenweider, Peter; Waeber, Gerard; Widen, Elisabeth; Cho, Yoon Shin; Olsen, Jesper V; Visscher, Peter M; Willer, Cristen; Franke, Lude; Erdmann, Jeanette; Thompson, John R; Pfeufer, Arne; Sotoodehnia, Nona; Newton-Cheh, Christopher; Ellinor, Patrick T; Stricker, Bruno H Ch; Metspalu, Andres; Perola, Markus; Beckmann, Jacques S

2013-01-01

305

Heart rate change as evidence for vaginally elicited orgasm and orgasm intensity  

Microsoft Academic Search

The purposes of this study were a) to further replicate previous findings on vaginal eroticism, using heart rate change as corroborative evidence for the subjective perception of sexual arousal and orgasm; and b) to investigate the correlation between heart rate change and subjective intensity of female orgasm. Heart rate measurements were obtained from ECG tracings. Eleven coitally experienced volunteers were

Heli Alzate; Bernardo Useche; Magdalena Villegas

1989-01-01

306

Dynamic analysis of heart rate may predict subsequent ventricular tachycardia after myocardial infarction  

NASA Technical Reports Server (NTRS)

Dynamics analysis of RR interval behavior and traditional measures of heart rate variability were compared between postinfarction patients with and without vulnerability to ventricular tachyarrhythmias in a case-control study. Short-term fractal correlation of heart rate dynamics was better than traditional measures of heart rate variability in differentiating patients with and without life-threatening arrhythmias.

Makikallio, T. H.; Seppanen, T.; Airaksinen, K. E.; Koistinen, J.; Tulppo, M. P.; Peng, C. K.; Goldberger, A. L.; Huikuri, H. V.

1997-01-01

307

Problem Behavior and Heart Rate Reactivity in Adopted Adolescents: Longitudinal and Concurrent Relations  

ERIC Educational Resources Information Center

The present longitudinal study examined resting heart rate and heart rate variability and reactivity to a stressful gambling task in adopted adolescents with aggressive, delinquent, or internalizing behavior problems and adopted adolescents without behavior problems (total N=151). Early-onset delinquent adolescents showed heart rate

Bimmel, Nicole; van IJzendoorn, Marinus H.; Bakermans-Kranenburg, Marian J.; Juffer, Femmie; De Geus, Eco J. C.

2008-01-01

308

Comparisons of high, medium, and low feedback sensitivity for the control of heart-rate acceleration  

Microsoft Academic Search

Thirty-four student volunteers were randomly assigned to one of three feedback sensitivity conditions: high sensitivity, medium sensitivity, or low sensitivity. Each subject received four sessions of biofeedback training with instructions to accelerate heart rate. In each condition, analogue feedback was provided during heart-rate acceleration trials. In addition to heart rate, frontal EMG and digital skin temperature were also recorded. Results

Donald A. Williamson; Mark P. Jarrell; John E. Monguillot; Peter Hutchinson

1983-01-01

309

Individual Differences in Human Operant Heart Rate Conditioning: Autonomic, Cognitive and Dispositional Concomitants  

Microsoft Academic Search

Research in human operant heart rate conditioning concerned with the elucidation of the mediators of operant heart rate changes has postulated five mediating mechanisms related to operant heart rate change: respiratory, somatic-muscular, central neurological, cognitive and dispositional (personality). However, examination of the literature indicates that much of this research has produced equivocal results, hence, a clear picture of mediation has

Paul Favaro

1979-01-01

310

Prognostic Value of Heart Rate Increase at Onset of Exercise Testing  

Microsoft Academic Search

Background—The initial response of heart rate to dynamic exercise has been proposed as having prognostic value in limited studies that have used modalities other than the treadmill. Our aim was to evaluate the prognostic value of early heart rate parameters in patients referred for routine clinical treadmill testing. Methods and Results—The heart rate rise at the onset of exercise was

Nicholas J. Leeper; Frederick E. Dewey; Euan A. Ashley; Marcus Sandri; Swee Yaw Tan; David Hadley; Jonathan Myers; Victor Froelicher

2010-01-01

311

Heart rate as a predictor of energy expenditure in people with spinal cord injury  

Microsoft Academic Search

This study evaluated the accuracy of heart rate calibrated from a maximum exercise test for predicting energy expenditure during five activities of daily living (ADL) in par- ticipants with spinal cord injury (SCI). Thirteen individuals with SCI underwent maximum exercise testing, followed by portable heart rate and metabolic testing during five ADL. A regression equation was developed from heart rate

Amy M. Hayes; Jonathan N. Myers; Monica Ho; Matthew Y. Lee; Inder Perkash; B. Jenny Kiratli

2005-01-01

312

Analysis of nonlinear and linear behaviors of heart rate for running exercise  

Microsoft Academic Search

This study investigates the nonlinear\\/linear behaviors of human heart rate response to treadmill exercise, for young and healthy subjects. The heart rate of the subject is measured, starting at a speed of 7 km\\/h, and increasing until the maximum heart rate for the subject is reached. The obtained nonlinear model is complicated and is not robust. Furthermore, sustained exercise at

Felician J More; Kevin Weng; Peter Mclean; Steven Su

2009-01-01

313

Effect of Heart Rate on Regulative Features of the Cortical Activity-Flow Coupling  

Microsoft Academic Search

Objective: Heart rate plays an important role in compensatory conditions of arterial pressure changes. Very little information, however, exists on its role in the dynamic adjustment of stimulated organ perfusion. We studied the influence of heart rate on the activity-flow coupling mechanism which adapts local cerebral blood flow in accordance with cortical activity. Since it does not affect heart rate

B. Rosengarten; C. Budden; S. Osthaus; M. Kaps

2003-01-01

314

Genome-wide association analysis identifies multiple loci related to resting heart rate  

Microsoft Academic Search

Higher resting heart rate is associated with increased cardiovascular disease and mortality risk. Though heritable factors play a substantial role in population variation, little is known about specific genetic determinants. This knowledge can impact clinical care by identifying novel factors that influence pathologic heart rate states, modulate heart rate through cardiac structure and function or by improving our understanding of

Mark Eijgelsheim; Christopher Newton-Cheh; Nona Sotoodehnia; Bakker de P. I. W; M. Müller; Alanna C. Morrison; Albert V. Smith; Aaron Isaacs; Serena Sanna; M. Dörr; P. Navarro; C. Fuchsberger; I. M. Nolte; Geus de E. J. C; K. Estrada; S.-J. Hwang; J. C. Bis; I.-M. Ruckert; A. Alonso; L. J. Launer; J. J. Hottenga; F. Rivadeneira Ramirez; P. A. Noseworthy; T. A. Rice; S. Perz; D. E. Arking; T. D. Spector; J. A. Kors; Y. S. Aulchenko; K. V. Tarasov; G. Homuth; S. H. Wild; F. Marroni; C. Gieger; C. M. M. Licht; R. J. Prineas; A. Hofman; J. I. Rotter; A. A. Hicks; F. D. J. Ernst; S. S. Najjar; A. F. Wright; A. Peters; E. R. Fox; B. A. Oostra; H. K. Kroemer; D. J. Couper; H. Völzke; H. Campbell; T. Meitinger; M. Uda; J. C. M. Witteman; B. M. Psaty; H.-E. Wichmann; T. B. Harris; S. Kääb; D. S. Siscovick; Y. Jamshidi; A. G. Uitterlinden; A. R. Folsom; M. G. Larson; J. F. Wilson; B. W. J. H. Penninx; H. Snieder; P. P. Pramstaller; P. Tikka-Kleemola; E. G. Lakatta; S. B. Felix; V. Gudnason; A. Pfeufer; S. R. Heckbert; B. H. Ch. Stricker; E. Boerwinkle; C. J. O'Donnell

2010-01-01

315

[A DSP-based design method for detecting fetal heart rate signals].  

PubMed

The paper presents the development and design of an ultrasonic Doppler fetal heart rate monitoring system based on DSP, and explains the realization of a algorithm for detecting fetal heart rate. Clinical practice has proved that this system is able to pick up the real-time fetal heart rate correctly and rapidly. PMID:17300006

Yang, Xiao-feng; Li, Peng; Zhang, Da-long; Bian, Zheng-zhong

2006-11-01

316

Heart rate variability and alternans formation in the heart: The role of feedback in cardiac dynamics.  

PubMed

A beat-to-beat alternation in the action potential duration (APD) of myocytes, i.e. alternans, is believed to be a direct precursor of ventricular fibrillation in the whole heart. A common approach for the prediction of alternans is to construct the restitution curve, which is the nonlinear functional relationship between the APD and the preceding diastolic interval (DI). It was proposed that alternans appears when the magnitude of the slope of the restitution curve exceeds one, known as the restitution hypothesis. However, this restitution hypothesis was derived under the assumption of periodic stimulation, when there is a dependence of the DI on the immediate preceding APD (i.e. feedback). However, under physiological conditions, the heart rate exhibits substantial variations in time, known as heart rate variability (HRV), which introduces deviations from periodic stimulation in the system. In this manuscript, we investigated the role of HRV on alternans formation in isolated cardiac myocytes using numerical simulations of an ionic model of the cardiac action potential. We used this model with two different pacing protocols: a periodic pacing protocol with feedback and a protocol without feedback. We show that when HRV is incorporated in the periodic pacing protocol, it facilitated alternans formation in the isolated cell, but did not significantly change the magnitude of alternans. On the other hand, in the case of the pacing protocol without feedback, alternans formation was prevented, even in the presence of HRV. PMID:24576615

McIntyre, Stephen D; Kakade, Virendra; Mori, Yoichiro; Tolkacheva, Elena G

2014-06-01

317

Time-variant modelling of heart rate responses to exercise intensity during road cycling  

Microsoft Academic Search

The aim of this study was to determine if heart rate responses to training intensity during road cycling could be modelled with compact time-variant mathematical model structures. The model performance was evaluated in terms of model order (complexity), number of inputs and parameter estimation methods used (time-invariant vs. time-variant). Thirteen male cyclists performed two identical cycling tests of 27 km

Joris Lefever; Daniel Berckmans; Jean-Marie Aerts

2012-01-01

318

[Heart rate: a risk factor or an epiphenomenon?].  

PubMed

The role of heart rate (HR) as an independent predictor of cardiovascular morbidity and mortality remains controversial. Direct evidence supporting a causal association between HR and prognosis is still lacking even if such relation appears plausible and may be inferred from epidemiological studies and clinical trials with HR lowering agents. The introduction of If current blocking agents, namely ivabradine, has offered the novel and unique opportunity to directly and exclusively interfere with HR and, thus, to validate the presence of a causal relationship between HR and prognosis. The BEAUTIFUL trial has recently confirmed that HR is a powerful negative prognostic predictor in patients with coronary artery disease and left ventricular systolic dysfunction. Particularly, subjects with a resting HR >70 b/min showed an increased risk of major adverse cardiovascular events. In these patients, HR reduction with ivabradine was associated with a reduction in major cardiac ischemic events, though not mortality. Further data will become available with the SHIFT trial in which patients with heart failure and HR > or =70 b/min are included and reduction in cardiovascular mortality and heart failure hospitalizations is the primary endpoint. PMID:20550061

Metra, Marco; Zacà, Valerio; Lombardi, Carlo; Bugatti, Silvia; Dei Cas, Livio

2010-03-01

319

Wireless patch sensor for remote monitoring of heart rate, respiration, activity, and falls.  

PubMed

Unobtrusive continuous monitoring of important vital signs and activity metrics has the potential to provide remote health monitoring, at-home screening, and rapid notification of critical events such as heart attacks, falls, or respiratory distress. This paper contains validation results of a wireless Bluetooth Low Energy (BLE) patch sensor consisting of two electrocardiography (ECG) electrodes, a microcontroller, a tri-axial accelerometer, and a BLE transceiver. The sensor measures heart rate, heart rate variability (HRV), respiratory rate, posture, steps, and falls and was evaluated on a total of 25 adult participants who performed breathing exercises, activities of daily living (ADLs), various stretches, stationary cycling, walking/running, and simulated falls. Compared to reference devices, the heart rate measurement had a mean absolute error (MAE) of less than 2 bpm, time-domain HRV measurements had an RMS error of less than 15 ms, respiratory rate had an MAE of 1.1 breaths per minute during metronome breathing, posture detection had an accuracy of over 95% in two of the three patch locations, steps were counted with an absolute error of less than 5%, and falls were detected with a sensitivity of 95.2% and specificity of 100%. PMID:24111135

Chan, Alexander M; Selvaraj, Nandakumar; Ferdosi, Nima; Narasimhan, Ravi

2013-01-01

320

A study on the rehabilitation of ischemic heart disease patients. The heart rate, beta-receptor blocking agents and strength-duration relationship of exercise.  

PubMed

Exercise tests with bicycle ergometer were performed in 9 normals and 54 patients with ischemic heart disease (IHD), in order to evaluate the heart rate (HR) as a parameter for determining the physical working capacity and controlling the daily activities, and to observe the circulatory and metabolic effects of beta-blockers and moreover to study the strength-duration relationship of exertion. The following results were obtained and discussed: 1. Reliable correlation between heart rate and O2 consumption during all phases of exercise, including the recovery period (R = 0.60-0.87, p less than 0.001) and parallelism of heart rate and pressure rate product allows the heart rate to be used as a parameter for myocardial O2 demand and ST-T changes. It is reasonable to evaluate the exercise effect by the net increment of heart rate during and after exercise, and to utilize the increment of heart rate in the recovery period for the evaluation of physical fitness and adaptability. 2. Similar to other studies made on beta-blockers, in this study too, the agents including Kö 1366 suppressed the exercise responses of heart rate (p less than 0.01), the product of heart rate and blood pressure (p less than 0.01), and O2 consumption (p less than 0.01). But a relatively slow recovery of O2 consumption from the peak response towards pre-exercise level and a higher O2 pulse in the early recovery period was observed after beta-blocker medication. 3. Capillary (ear lobe) pH decreased and recovered in correlation with the strength of exertion. This corresponded with the response of other factors such as ST-T, heart rate, pressure-rate product, and O2 consumption, showing that the exercise strength was one of the more dominant factors to determine allowable work load for ischemic heart disease patients. 4. Recovery of pH was delayed after medication with Kö 1366 (p less than 0.01). PMID:240049

Kamyar, G A

1975-09-01

321

Decreased heart rate variability is associated with poststroke depression  

PubMed Central

Objective Although decreased heart rate variability (HRV) has been well documented in association with depression following myocardial infarction, this phenomenon has not been studied in patients with stroke. The present study was designed to prospectively assess HR in relationship to depression among patients with acute stroke. Design Using 24 hour Holter monitoring, assess HRV. Setting A large university rehabilitation hospital. Participants patients, with first ever stroke and no other severe physical illness, cigarette smoking or drug therapy that could affect HRV, were evaluated over 24 hours for heart rate variability. Measurements Patients were evaluated using the Structured Clinical Interview for depression diagnosis. Severity was assessed by Hamilton Depression Rating Scale. Stroke severity was assessed by the NIH Stroke Scale, the Barthel Index and the Mini Mental State Exam. The standard deviation of time in msec between normal heart beats (SDNN) was the primary measure of HRV. Results Among patients with poststroke major or minor depression (N=33), the SDNN was 109±32.6 SD compared with nondepressed patients (N=16) whose SDNN was 133.9±40.1 SD(Wilcoxon rank test S=492, p=0.048). The SDNN was significantly and independently related to the existence of depression, but no other intergroup differences. Conclusions These findings, for the first time, have provided some evidence that both major and minor poststroke depression may lead to decreased HRV. Future research in larger groups of patients should determine whether other measures of HRV more specific to sympathetic-parasympathetic tone are decreased in patients with poststroke depression.

Spalletta, Gianfranco; Jorge, Ricardo E.; Bassi, Andrea; Colivicchi, Furio; Ripa, Alessandra; Caltagirone, Carlo

2008-01-01

322

Prospective study of fetal heart rate and rhythm patterns.  

PubMed Central

The fetal heart beat, detected by ultrasound, was recorded for five minutes from 934 antenatal women--266 at 30 to 35 weeks' gestation and 718 at 36 to 41 weeks. Episodes of bradycardia < 100/minute ranging from 5-30 seconds' duration occurred in 3 (1.1%) of the former and in 9 (1.3%) of the latter group. Tachycardia > 180/minute ranging from 30-90 seconds' duration occurred in 1 (0.4%) of the former and in 4 (0.6%) of the latter. Premature beats were not detected between 30 and 35 weeks, but occurred in 12 (1.7%) of 720 at 36 to 41 weeks' gestation. 50 subjects were monitored at both 30 and 35 weeks and 36 to 41 weeks' gestation and in one woman premature beats were present in the latter but not in the former recording. The incidence (1.7% of premature beats in the fetus at 36 to 41 weeks' gestation was similar to that in the healthy neonate (0.8%). Recordings of arrhythmias or rates outside the range 100-180/minute were replayed through a standard antepartum fetal heart rate monitor. The monitor failed to detect premature beats, 2 to 4 episodes of tachycardia > 180/minute, and 9 of 12 episodes of bradycardia < 100/minute, stressing its unreliability for detecting rapidly changing rates.

Southall, D P; Richards, J; Hardwick, R A; Shinebourne, E A; Gibbens, G L; Thelwall-Jones, H; de Swiet, M; Johnston, P G

1980-01-01

323

Determination of Performance Criteria for Artificial Hearts.  

National Technical Information Service (NTIS)

CONTENTS: Reliability and quality assurance - the primary performance criteria; Technical performance criteria; Economic and sociologic criteria; Facilities criteria; Overall figure of merit; Summary of performance criteria.

1966-01-01

324

The effect of physical training upon the mechanical and metabolic performance of the rat heart  

PubMed Central

The dynamic and metabolic performance of rats conditioned by a swimming program (CH) and hearts of sedentary rats (SH) was studied in an isolated working rat heart apparatus. Heart rate, filling pressure, and afterload were controlled or kept constant, and heart weights were comparable in both groups. When compared with SH, CH had increased cardiac output and cardiac work. Atrial pacing at more rapid rates caused greater differences in these functions, and left ventricular pressure and maximal rate of pressure rise (dp/dt) became higher in CH than in SH. Atrial pacing was associated in CH with increased oxygen consumption but in SH by increased lactate and pyruvate production. When atrial filling pressure was elevated in order to perform ventricular function curves, CH showed greater dynamic responses than SH. There were also greater increments in oxygen consumption, and the ratio of aerobic to anaerobic energy production was also higher in CH. The mechanism of increasing oxygen consumption during stress in CH was mainly by improved coronary flow. In SH coronary flow did not change, but extraction of oxygen from the perfusing fluid increased. The results indicate that in physically trained rats the function of the heart as a pump is improved. These hearts have greater aerobic and mechanical reserve than hearts of sedentary animals. These effects appear to be at least partially due to improved mechanisms of oxygen delivery.

Penpargkul, Somsong; Scheuer, James

1970-01-01

325

Circadian pattern of blood pressure and heart rate in the longer term after heart transplantation.  

PubMed

A loss of the circadian rhythm pattern of the blood pressure (BP) and heart rate (HR) as well as the development of hypertension has been found after heart transplantation (Htx). To determine whether a reappearance of this rhythm occurs in the long term after Htx, we used 24-h ambulatory monitoring to study 27 patients 1.7+/-1.6 years (range of 10 days to 4.3 years) after Htx. Patients were divided into two groups: group I (short term), Htx less than 6 months (n = 7); and group 2 (long term), Htx more than 6 months previously (n = 20). Group 2 had significantly higher diastolic BP as well as a greater fall in systolic BP during the night (-0.4+/-8.0 vs. 9.0+/-7.2 mm Hg, p < 0.01). There was also a higher day HR found in group 2 (73.2+/-14.5 vs. 96.8+/-12.5 beats/min, p < 0.001) as well as a larger fall in night HR in group 2 (4.2+/-5.5 vs. 11.9+/-4.9 beats/min, p < 0.005). The return of the circadian rhythm pattern in the longer term after Htx may result from partial reinervation of the heart, although other neurohumoral factors or concomitant medication (lower steroid dosages) may play a role. PMID:11527142

von Pölnitz, A; Bracht, C; Kemkes, B; Höfling, B

1990-01-01

326

Prognostic significance of heart rate turbulence parameters in patients with chronic heart failure  

PubMed Central

Background This study is aimed to evaluate the clinical significance of heart rate turbulence (HRT) parameters in predicting the prognosis in patients with chronic heart failure (CHF). Methods From June 2011 to December 2012, a total of 104 CHF patients and 30 healthy controls were enrolled in this study. We obtained a 24-hour Holter ECG recording to assess the HRT parameters, included turbulence onset (TO), turbulence slope (TS), standard deviation of N-N intervals (SDNN), and resting heart rate (RHR). The relationships between HRT parameters and the prognosis of CHF patients were determined. Results The assessment follow-up period lasted until January 31, 2013. The overall mortality of CHF patients was 9.6% (10/104). Our results revealed that CHF patients had higher levels of TO than those of healthy subjects, but the TS levels of CHF patients were lower than that of the control group. CHF patients with NYHA grade IV had higher HRT1/2 rate than those with NYHA grade II/III. There were statistical differences in TS, LVEF, SDNN and RHR between the non-deteriorating group and the non-survivor group. Significant differences in TS among the three groups were also found. Furthermore, CHF patients in the non-survivor group had lower levels of TS than those in the deteriorating group. Correlation analyses indicated that TO negatively correlate with SDNN, while TS positively correlated with SDNN and left ventricular ejection fraction (LVEF). We also observed negative correlations between TS and left ventricular end-diastolic cavity dimension (LVEDD), RHR, homocysteine (Hcy) and C-reactive protein (CRP). Multivariate Cox regression analysis further confirmed that LVEF (?30%), HRT2, SDNN and RHR were independent risk factors which can indicate poor prognosis in CHF patients. Conclusions Our findings indicate that HRT may have good clinical predictive value in patients with CHF. Thus, quantifying HRT parameters could be a useful tool for predicting mortality in CHF patients.

2014-01-01

327

Determinants for Heart Rate Variability in a Normal Korean Population  

PubMed Central

This study examined the normal ranges and the determinants for various parameters of the short-term heart rate variability (HRV) measurements in a large Korean sample of healthy people. HRV measurements were obtained in 2,748 healthy men and 735 healthy women 18-65 yr of age. The mean total power (TP), low frequency (LF), high frequency (HF), and LF/HF ratio were 1,358.9 ± 1,840.8 ms2, 417.3 ± 807.6 ms2, 254.1 ± 414.1 ms2, and 2.4 ± 20.9 ms2 in the frequency-domain spectral analysis. The mean standard deviation of the normal-to-normal (NN) interval (SDNN) and the square root of the mean squared differences of successive NN intervals (RMSSD) were 39.6 ± 22.1 ms and 29.7 ± 18.1 ms in the time-domain analysis. The female subjects had significantly higher SDNN, RMSSD, and HF values than the male subjects. After controlling for age, there was no statistically significant difference in the SDNN. Quantile regression analysis showed that age and mean heart rate had a significant impact on short-term HRV measurement. Given that both clinicians and researchers are increasingly relying on short-term HRV assessment in measuring stress, our work suggests that age and gender should be considered as independent determinants for HRV.

Kim, Gyung-Mee

2011-01-01

328

Determinants for heart rate variability in a normal Korean population.  

PubMed

This study examined the normal ranges and the determinants for various parameters of the short-term heart rate variability (HRV) measurements in a large Korean sample of healthy people. HRV measurements were obtained in 2,748 healthy men and 735 healthy women 18-65 yr of age. The mean total power (TP), low frequency (LF), high frequency (HF), and LF/HF ratio were 1,358.9 ± 1,840.8 ms(2), 417.3 ± 807.6 ms(2), 254.1 ± 414.1 ms(2), and 2.4 ± 20.9 ms(2) in the frequency-domain spectral analysis. The mean standard deviation of the normal-to-normal (NN) interval (SDNN) and the square root of the mean squared differences of successive NN intervals (RMSSD) were 39.6 ± 22.1 ms and 29.7 ± 18.1 ms in the time-domain analysis. The female subjects had significantly higher SDNN, RMSSD, and HF values than the male subjects. After controlling for age, there was no statistically significant difference in the SDNN. Quantile regression analysis showed that age and mean heart rate had a significant impact on short-term HRV measurement. Given that both clinicians and researchers are increasingly relying on short-term HRV assessment in measuring stress, our work suggests that age and gender should be considered as independent determinants for HRV. PMID:22022180

Kim, Gyung-Mee; Woo, Jong-Min

2011-10-01

329

Conditioned tolerance to the heart rate effects of smoking.  

PubMed

This study extended our findings that behavioral tolerance to nicotine in animals can be influenced by conditioning to cardiovascular tolerance in humans. Subjects smoked one-half a cigarette during each of five trials. In the ten-minute intersmoking interval the contexts that preceded smoking were varied. Smokers in the Changing group attended to a different five-minute segment of a Sherlock Holmes radio mystery before each trial, while those in the Repeated group listened to the same segment of the tape. Presmoking heart rates were stable across the groups from trials 1 to 5. As predicted, heart rate for subjects who smoked in the same context showed tolerance to smoking from trials 1 to 5 (84.5 to 78 bpm), while subjects who smoked in in the same context showed tolerance to 83.9 bpm). COa levels increased equally for both groups over the five trials. The results of this study suggest tolerance to smoking can be influenced by learning. PMID:1924497

Epstein, L H; Caggiula, A R; Perkins, K A; McKenzie, S J; Smith, J A

1991-05-01

330

Investigation of noise exposure effect on heart rate variability parameters.  

PubMed

This paper deals with the study of the effect of 135 min exposure to noise with intensity Leq 95 dB(A) in experimental conditions. Three experimental sessions: before, at the onset, and at the end of the noise exposure were conducted. The comparison of heart rate variability (HRV) parameters before and on the onset of the experiment showed tendency for significant decrease of the cardiointervals variability parameters: standard deviation (SD), sum of positive differences between successive cardiointervals (S), total wave energy in the cardiotachogram (S*Ns), mean difference between successive cardiointervals (V). Statistically significant increase of the mean value was found at HRV parameters related to the distribution of the cardiointervals: control adequacy parameter (IARP), equilibrium autonomic parameter (IVE), autonomous balance (IVB), homeostasis parameter (HI). At the end of the third experimental session HRV parameters were almost restored, but they did not achieve the initial values. An elevation of the sympathetic activity under noise exposure effect was found. In this aspect, the heart rate variability parameters were interpreted as a sensitive indicator for the quality of cardiac rhythm and they can be used for assessment of the functional status and the level of preserving of the adaptive reserves of the investigated persons. PMID:11505734

Tzaneva, L; Danev, S; Nikolova, R

2001-08-01

331

Online heart rate estimation in unstable ballistocardiographic records.  

PubMed

When recording the pressure oscillations of a seated subject two distinct effects are assessed, ample vibrations due to the person's movement, and periodic oscillations of small amplitude due to cardiopulmonary activity, expressed by the ballistocardiogram (BCG). Embedding a pressure sensor in a chair's back or seat allows unobtrusive monitoring of the BCG. However, inconspicuously acquired signals are affected by numerous artifacts, often generated by the subject's forgetfulness, and posture changes due to lack of constrains. Moreover, the signal changes considerably its shape from person to person, and when the seating posture, or conversely, sensor position, is different. For real-time continuous monitoring, it is still to be found a method which, without introducing significant delays, can deal with such volatility. Thus, tailored calibration of peak detectors and other algorithms is recurrent, and even so, the neighboring samples of artifacts are possibly untreatable. This work evaluates the advantages of Empirical Mode Decomposition, as well as a coarser demodulation approach of the BCG signal, as dependable methods to allow real-time heart rate estimation on unstable BCG records. An analysis of the Fourier transform of the demodulated signals is the method used to provide and compare robustness of heart rate estimates. PMID:21096778

Pinheiro, Eduardo C; Postolache, Octavian A; Girão, Pedro S

2010-01-01

332

Heart rates increase after hatching in two species of Natricine snakes.  

PubMed

Experimental studies have shown heart rates to decrease from embryo to hatchling stage in turtles, remain steady in skinks, and increase in birds. However, no snake species has been studied in this regard. I recorded heart rate evolution trajectories from embryo to juvenile stage in 78 eggs from two species of European Natricine snakes. Unexpectedly, snakes behaved more like birds than turtles or lizards: heart rates increased after hatching in both N. maura and N. natrix, respectively by 43.92 ± 22.84% and 35.92 ± 24.52%. Heart rate shift was not related to an abrupt elevation of metabolism per se (snakes that increased their heart rates the most sharply grew the least after birth), but rather due to a number of smaller eggs that experienced lower than normal heart rates throughout the incubation and recovered a normal heart rate post-birth. This finding is discussed in the light of hatching synchrony benefits. PMID:24287712

Aubret, Fabien

2013-01-01

333

Heart rates increase after hatching in two species of natricine snakes  

PubMed Central

Experimental studies have shown heart rates to decrease from embryo to hatchling stage in turtles, remain steady in skinks, and increase in birds. However, no snake species has been studied in this regard. I recorded heart rate evolution trajectories from embryo to juvenile stage in 78 eggs from two species of European Natricine snakes. Unexpectedly, snakes behaved more like birds than turtles or lizards: heart rates increased after hatching in both N. maura and N. natrix, respectively by 43.92 ± 22.84% and 35.92 ± 24.52%. Heart rate shift was not related to an abrupt elevation of metabolism per se (snakes that increased their heart rates the most sharply grew the least after birth), but rather due to a number of smaller eggs that experienced lower than normal heart rates throughout the incubation and recovered a normal heart rate post-birth. This finding is discussed in the light of hatching synchrony benefits.

Aubret, Fabien

2013-01-01

334

Heart Rate and Blood Pressure: Any Possible Implications for Management of Hypertension?  

PubMed Central

Hypertension is a common clinical problem and a major risk factor for cardiovascular disease and stroke. Elevated heart rate is associated with elevated blood pressure, increased risk for hypertension, and, among hypertensives, increased risk for cardiovascular disease. Despite these important relationships, heart rate is generally not a major consideration in choosing antihypertensive medications. In part, this is due to a lack of evidence supporting heart rate lowering as a therapeutic strategy in hypertension. Additionally, while there is a positive correlation between heart rate and peripheral blood pressure, there is an inverse relationship between heart rate and central blood pressure. The use of antihypertensive medications, specifically medications that affect heart rate, may not reliably reduce central blood pressure to a similar extent as observed peripherally. We review the relationship between heart rate and peripheral and central blood pressure, with a focus on the implications for chronotropic therapy in hypertension.

Reule, Scott; Drawz, Paul E.

2012-01-01

335

Coherence between heart rate and dominant frequency of the time-frequency heart rate variability spectrum as ischemic marker in the exercise test  

Microsoft Academic Search

Observation on heart rate (HR) and heart rate variability (HRV) trends in exercise ECGs lead us to hypothesize that some correlation exists between the evolution of HR and the dominant HRV frequency, which may differ in ischemic and healthy subjects. The ECGs recordings from stress test trials were collected and clustered into four groups: ischemic (positive coronary angiography), non-ischemic, volunteers

M. Canales; J. Mateo; R. Bailon; P. Laguna; P. Serrano

2003-01-01

336

HEART RATE VARIABILITY DURING RECOVERY IN TWO GROUPS WITH DIFFERENT TRAINING LEVEL  

Microsoft Academic Search

Heart Rate Variability (HRV) study, beside having a clini- cal interest, it has also worried researchers in exercise re- sponse and training adaptation. Although heart rate recov- ery (HRR) has been used as a cardiovascular index in mul- tiple tests, there is little information about the physiological mechanisms that explain the process of heart recovery af- ter exercise (1). Objective.

Lorenzo Irma; Calderón Francisco Javier; Benito Pedro

337

Modulation of cardiac A 1 -adenosine receptors in rats following treatment with agents affecting heart rate  

Microsoft Academic Search

Effects of chronic treatment affecting heart rate on A1 adenosine receptor levels and their functions were studied. Treatment of rats with isoproterenol for 10 days accelerated heart rate and increased the level of adenosine receptors, in both the atria and ventricles. Negative dromotropic response of isolated heart to adenosine was enhanced in isoproterenol-treated rats. Similar results were obtained following treatment

Nissim Balas; Michael Arad; Babeth Rabinowitz; Asher Shainberg

2002-01-01

338

Tracking control and robustness analysis for a nonlinear model of human heart rate during exercise  

Microsoft Academic Search

The control of human heart rate during exercise is an important problem that has implications for the development of protocols for athletics, assessing physical fitness, weight management, and the prevention of heart failure. Here we provide a new stabilization technique for a recently-proposed nonlinear model for human heart rate response that describes the central and peripheral local responses during and

Frédéric Mazenc; Michael Malisoff; Marcio de Querioz

2011-01-01

339

Determinants of Heart Rate Recovery in Patients with Suspected Coronary Artery Disease  

Microsoft Academic Search

Background: Heart rate recovery after exercise is an independent prognostic indicator for cardiovascular and all-cause mortality. The purpose of this study was to clarify the clinical determinants of heart rate recovery. Methods and results: We examined 114 consecutive male patients who underwent exercise myocardial perfusion single-photon emission computed tomography and echocardiography for the evaluation of suspected coronary artery disease. Heart

AKIKO NONAKA; HIDEYUKI SHIOTANI; KIMIKO KITANO; MITSUHIRO YOKOYAMA

340

Heart rate and heart rate variability in pregnant warmblood and Shetland mares as well as their fetuses.  

PubMed

Heart rate (HR) is an important parameter of fetal well-being. In horses, HR and heart rate variability (HRV) can be determined by fetomaternal electrocardiography (ECG) from mid-pregnancy to foaling. Normal values for physiological parameters in larger breeds are often used as reference values in ponies. However, HR increases with decreasing size of the animal and in ponies is higher than in warmblood horses. It is not known if fetal HR is affected by breed and if values obtained in larger breeds can be used to assess Shetland fetuses. We have determined fetomaternal beat-to-beat (RR) interval (inversely correlated to HR) and HRV in warmblood (n=6) and Shetland pregnancies (n=7) at days 280 and 300 of gestation by ECG. Maternal RR interval was lower in pony than in warmblood mares (day 280: Shetland: 958±110, warmblood: 1489±126ms, p<0.01) The SDRR (standard deviation of RR interval) and the RMSSD (root mean square of successive RR differences) did not differ between breeds at any time. Also RR interval as well as HRV did not differ between warmblood and pony fetuses (RR interval day 280: Shetland: 606±39, warmblood: 589±38ms). In conclusion, although maternal RR interval is clearly higher in Shetland than in warmblood mares, fetal RR interval in the two breeds is on the same level. PMID:21907506

Nagel, Christina; Aurich, Jörg; Palm, Franziska; Aurich, Christine

2011-09-01

341

Maximal constant heart rate--a heart rate based method to estimate maximal lactate steady state in running.  

PubMed

The aim of the present study was to investigate the accuracy of the maximal constant heart rate method for predicting anaerobic threshold (AnT) in running. This method only requires a common heart rate (HR) monitor and is based on the identification of the maximal constant HR maintainable for 30 min (HRMC). HRMC, 4-mmol threshold, and maximal lactate steady state (MLSS) were determined in 31 probands. 17 probands underwent an additional MLSS retest within 2 weeks. The correlation between HR at MLSS and at MLSS retest was very close (r = 0.807; SEE = 5.25 beats x min(-1); p < 0.001). So were the correlations between HR at 4-mmol threshold and MLSS (r = 0.844; SEE = 6.43 beats x min(-1); p < 0.001) and between HRMC and HR at MLSS (r = 0.820; SEE = 6.73 beats x min(-1); p < 0.001). Mean velocities at maximum constant HR trials and MLSS (r = 0.895; SEE = 0.185 m x s(-1); p < 0.001) as well as 4-mmol threshold and MLSS (r = 0.899; SEE = 0.186 m x s(-1); p < 0.001) were highly correlated. In conclusion, data presented in this study confirm that the determination of HRMC is a manageable method giving a highly accurate estimation of both HR and velocity at MLSS in running. PMID:16729378

Vobejda, C; Fromme, K; Samson, W; Zimmermann, E

2006-05-01

342

Development of a Heart Rate Monitor Based on an Ear Phone  

Microsoft Academic Search

\\u000a It is important to continuously monitor health information in daily life under u-Healthcare environments, and some simple\\u000a and unconstraint measurement methods are also required to perform such continuous monitoring. Thus, this study developed a\\u000a Heart Rate Monitor (HRM) that is a type of PPG based ear phone for achieving easy wearability and removed moving artifacts\\u000a using an accelerometer in order

K. R. Chung; G. S. Hong; C. Choi; H. J. Yoon; J. H. Hyeong; S. Y. Kim

343

Mechanical heart valves: Changes in patient survival and valve failure rates  

Microsoft Academic Search

The effect of patient related variables and mechanical heart valve substitutes on survival and valve failure rates was studied\\u000a in 2,778 patients operated between 1966 and 1986. Of these 48.2% were operated without cardioplegic protection (phase I) and\\u000a 51.8% thereafter (phase II). Mitral vlave replacement (MVR) was performed in 1,257 patients (phase I: 51.58%, phase II: 48.42%);\\u000a aortic valve replacement

T. K. Kaul; J. L. Mercer; D. R. Ramsdale

1992-01-01

344

Marijuana and ethanol: Differential effects on time perception, heart rate, and subjective response  

Microsoft Academic Search

Performance on a time production task, heart rate, and subjective responses were studied in twelve male subjects given oral doses of marijuana (0.7 mg of delta-9-tetrahydrocannabinol\\/kg), ethanol (1.0 ml\\/kg), and placebo, on three testing days which were each separated by 1 week. Orders were balanced across subjects and testing conditions were doubleblind. Compared to ethanol and placebo, marijuana induced a

Jared R. Tinklenberg; Walton T. Roth; Bert S. Kopell

1976-01-01

345

Modified autonomic balance in offsprings of diabetics detected by spectral analysis of heart rate variability  

Microsoft Academic Search

This study was performed to evaluate the influence of family history for non[ndash ]insulin-dependent diabetes mellitus (NIDDM) on autonomic balance. The latter was assessed by spectral analysis of heart rate variability (SA-HRV) and by analyzing the relative contribution of low-frequency (LF) and high-frequency (HF) components. Twenty glucose normotolerant offsprings of NIDDM parents and 20 controls underwent a 1-hour continuous electrocardiogram

Claudio De Angelis; Pietro Perelli; Roberto Trezza; Maria Casagrande; Roberto Biselli; Gaetano Pannitteri; Benedetto Marino; Stefano Farrace

2001-01-01

346

Several common variants modulate heart rate, PR interval and QRS duration  

Microsoft Academic Search

Electrocardiographic measures are indicative of the function of the cardiac conduction system. To search for sequence variants that modulate heart rate, PR interval and QRS duration in individuals of European descent, we performed a genome-wide association study in ?10,000 individuals and followed up the top signals in an additional ?10,000 individuals. We identified several genome-wide significant associations (with P <

Daniel F Gudbjartsson; David O Arnar; Gudmar Thorleifsson; Gudmundur Thorgeirsson; Hrafnhildur Stefansdottir; Sigurjon A Gudjonsson; Aslaug Jonasdottir; Ellisiv B Mathiesen; Inger Njølstad; Audhild Nyrnes; Tom Wilsgaard; Erin M Hald; Kristian Hveem; Camilla Stoltenberg; Maja-Lisa Løchen; Augustine Kong; Unnur Thorsteinsdottir; Hilma Holm; Kari Stefansson

2010-01-01

347

Can extremely low frequency alternating magnetic fields modulate heart rate or its variability in humans?  

Microsoft Academic Search

This study is a reexamination of the possibility that exposure to extremely low frequency alternating magnetic field (ELF-MF) may influence heart rate (HR) or its variability (HRV) in humans. In a wooden room (cube with 2.7-m sides) surrounded with wire, three series of experiments were performed on 50 healthy volunteers, who were exposed to MFs at frequencies ranging from 50

Yoshika Kurokawa; Hiroshi Nitta; Hideki Imai; Michinori Kabuto

2003-01-01

348

Is the polar f6 heart rate monitor less accurate during aerobic bench stepping because of arm movements?  

PubMed

Lloyd, LK, Crixell, SH, and Price, LR. Is the polar F6 heart rate monitor less accurate during aerobic bench stepping because of arm movements? J Strength Cond Res 28(7): 1952-1958, 2014-Because of the well-documented linear relationship between heart rate and oxygen consumption (V[Combining Dot Above]O2), heart rate is commonly used to estimate energy expenditure during exercise. However, previous research suggests that heart rate increases without a concomitant rise in V[Combining Dot Above]O2 when arm movements are added to exercise. If so, this could impact the accuracy of heart rate monitors in estimating energy expenditure during combined arm and leg exercise. This study compared the cardiorespiratory responses to a bench step aerobics routine performed with and without arm movements and evaluated whether the accuracy of the Polar F6 heart rate monitor in predicting energy expenditure was impacted by the inclusion of arm movements. Thirty-two women performed the same routine with and without arm movements while stepping up and down off of a 15.24-cm bench at a cadence of 128 b·min. Heart rate and V[Combining Dot Above]O2 increased, whereas oxygen pulse (V[Combining Dot Above]O2·heart rate) decreased when arm movements were added (p < 0.001). However, the differences between the energy expenditure estimated by the Polar F6 heart rate monitor and the energy expenditure measured by indirect calorimetry were similar during the same aerobic bench stepping routine performed with and without arms (??2 kCal·min, p ? 0.05). Results confirm that arm movements during aerobic bench stepping elicit a disproportionate rise in heart rate relative to V[Combining Dot Above]O2. However, results do not support that these movements increase the prediction error in energy expenditure, as the Polar F6 heart rate monitor over predicted energy expenditure when arm movements were involved and when they were not involved. PMID:24448006

Lloyd, Lisa K; Crixell, Sylvia H; Price, Larry R

2014-07-01

349

Heart rate variability in risk stratification of cardiac patients.  

PubMed

Heart rate (HR) variability has been extensively studied in cardiac patients, especially in patients surviving an acute myocardial infarction (AMI) and also in patients with congestive heart failure (CHF) or left ventricular (LV) dysfunction. The majority of studies have shown that patients with reduced or abnormal HR variability have an increased risk of mortality within a few years after an AMI or after a diagnosis of CHF/LV dysfunction. Various measures of HR dynamics, such as time-domain, spectral, and non-linear measures of HR variability have been used in risk stratification. The prognostic power of various measures, except of those reflecting rapid R-R interval oscillations, has been almost identical, albeit some non-linear HR variability measures, such as short-term fractal scaling exponent have provided somewhat better prognostic information than the others. Abnormal HR variability predicts both sudden and non-sudden cardiac death. Because of remodeling of the arrhythmia substrate after AMI, early measurement of HR variability to identify those at high risk should likely be repeated later in order to assess the risk of fatal arrhythmia events. Future randomized trials using HR variability/turbulence as one of the pre-defined inclusion criteria will show whether routine measurement of HR variability/turbulence will become a routine clinical tool for risk stratification of cardiac patients. PMID:24215747

Huikuri, Heikki V; Stein, Phyllis K

2013-01-01

350

The predictive value of resting heart rate following osmotherapy in brain injury: back to basics  

PubMed Central

Background The importance of resting heart rate as a prognostic factor was described in several studies. An elevated heart rate is an independent risk factor for adverse cardiovascular events and total mortality in patients with coronary artery disease, chronic heart failure, and the general population. Also heart rate is elevated in the Multi Organ Dysfunction Syndrome (MODS) and the mortality due to MODS is highly correlated with inadequate sinus tachycardia. To evaluate the value of resting heart rate in predicting mortality in patients with traumatic brain injury along scoring systems like Acute Physiology and Chronic Health Evaluation(APACHE II), Sequential Organ Failure Assessment (SOFA) and Glasgow Coma Score (GCS). Method By analyzing data which was collected from an open labeled randomized clinical trial that compared the different means of osmotherapy (mannitol vs bolus or infusion hypertonic saline), heart rate, GCS, APACHE II and SOFA score were measured at baseline and daily for 7 days up to 60 days and the relationship between elevated heart rate and mortality during the first 7 days and 60th day were assessed. Results After adjustments for confounding factors, although there was no difference in mean heart rate between either groups of alive and expired patients, however, we have found a relative correlation between 60th day mortality rate and resting heart rate (P=0.07). Conclusion Heart rate can be a prognostic factor for estimating mortality rate in brain injury patients along with APACHE II and SOFA scores in patients with brain injury.

2012-01-01

351

Should the augmentation index be normalized to heart rate?  

PubMed

Pulse wave analysis(PWA) is widely used to investigate systemic arterial stiffness. The augmentation index(AIx), the primary outcome derived from PWA, is influenced by the mean arterial pressure(MAP), age, gender and heart rate(HR). Gender- and age-specific reference values have been devised, and it is recommended that the MAP be used as a statistical covariate. The AIx is also commonly statistically adjusted to a HR of 75 b·min(-1); however, this approach may be physiologically and statistically inappropriate. First, there appears to be an important physiological chronic interaction between HR and arterial stiffness. Second, the method used to correct to HR assumes that the relationship with AIx is uniform across populations. A more appropriate practice may be to include HR as an independent predictor or covariate; this approach is particularly recommended for longitudinal studies, in which changes in HR may help to explain changes in arterial stiffness. PMID:24257465

Stoner, Lee; Faulkner, James; Lowe, Andrew; M Lambrick, Danielle; M Young, Joanna; Love, Richard; S Rowlands, David

2014-01-23

352

Correlated and uncorrelated heart rate fluctuations during relaxing visualization  

NASA Astrophysics Data System (ADS)

The heart rate variability (HRV) of healthy subjects practicing relaxing visualization is studied by use of three multiscale analysis techniques: the detrended fluctuation analysis (DFA), the entropy in natural time (ENT) and the average wavelet (AWC) coefficient. The scaling exponent of normal interbeat interval increments exhibits characteristics of the presence of long-range correlations. During relaxing visualization the HRV dynamics change in the sense that two new features emerge independent of each other: a respiration-induced periodicity that often dominates the HRV at short scales (<40 interbeat intervals) and the decrease of the scaling exponent at longer scales (40-512 interbeat intervals). In certain cases, the scaling exponent during relaxing visualization indicates the breakdown of long-range correlations. These characteristics have been previously seen in the HRV dynamics during non-REM sleep.

Papasimakis, N.; Pallikari, F.

2010-05-01

353

Heart rate variability at different thermal comfort levels.  

PubMed

The mechanism of human thermal comfort is important for building a comfortable and healthy indoor environment. This paper analyzes human heart rate variability (HRV) at different thermal comfort levels and discusses the mechanism of human thermal comfort. A total of 33 subjects were divided in 3 groups. Under air temperatures of 21, 24, 26, 28, 29, and 30 degrees C, the subjects' electrocardiogram was recorded for 5 min. HRV (the ratio of absolute powers in low- and high-frequency bands, LF/HF ratio) was analyzed. LF/HF at discomfort level were significantly higher than that at comfort level (P < 0.05), despite the same thermal sensation. The results indicate that sympathetic activity plays an important role in subjects' thermal discomfort and the LF/HF ratio may be used as an indicator for human thermal comfort. PMID:18351379

Liu, Weiwei; Lian, Zhiwei; Liu, Yuanmou

2008-06-01

354

Heart Rate Recovery in Patients With Hypertrophic Cardiomyopathy  

PubMed Central

Recovery in heart rate (HR) after exercise is a measure of autonomic function and a prognostic indicator in cardiovascular disease. The aim of this study was to characterize heart rate recovery (HRR) and to determine its relation to cardiac function and morphology in patients with hypertrophic cardiomyopathy (HC). We studied 18 healthy volunteers and 41 individuals with HC. All patients underwent clinical assessment and transthoracic echocardiography. Continuous beat-by-beat assessment of HR was obtained during and after cardiopulmonary exercise testing using finger plethysmography. HRR and power spectral densities were calculated on 3 minutes of continuous RR recordings. Absolute HRR was lower in patients than that in controls at 1, 2, and 3 minutes (25.7 ± 8.4 vs 35.3 ± 11.0 beats/min, p <0.001; 36.8 ± 9.4 vs 53.6 ± 13.2 beats/min, p <0.001; 41.2 ± 12.2 vs 62.1 ± 14.5 beats/min, p <0.001, respectively). HRR remained lower in patients at 2 and 3 minutes after normalization to peak HR. After normalization to the difference in HR between peak exercise and rest, HRR was significantly impaired in individuals with obstructive HC at 3 minutes compared with controls. HR at 3 minutes correlated with peak left ventricular outflow tract gradient (B 0.154 beats/min/mm Hg, confidence interval 0.010 to 0.299, p = 0.037) and remained a significant predictor of HRR after multivariable analysis. Spectral analysis showed a trend toward an increased low-frequency to high-frequency ratio in patients (p = 0.08) suggesting sympathetic predominance. In conclusion, HRR is impaired in HC and correlates with the severity of left ventricular outflow tract gradient. Prospective studies of the prognostic implications of impaired HRR in HC are warranted.

Patel, Vimal; Critoph, Christopher H.; Finlay, Malcolm C.; Mist, Bryan; Lambiase, Pier D.; Elliott, Perry M.

2014-01-01

355

Heart Rate Variability and Markers of Inflammation and Coagulation in Depressed Patients with Coronary Heart Disease  

PubMed Central

Background Depression is associated with an increased risk for cardiac morbidity and mortality in patients with coronary heart disease(CHD). Cardiac autonomic nervous system (ANS) dysregulation, proinflammatory processes, and procoagulant processes, have been suggested as possible explanations. Methods Heart rate variability (HRV), an indicator of cardiac autonomic regulation, and markers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor (TNF?)] and coagulation (fibrinogen) were assessed in 44 depressed patients with CHD. Results Moderate, negative correlations were found between fibrinogen and four measures of HRV. Il-6 also negatively correlated with one measure of HRV (total power), and was marginally related to two others (very low frequency and low frequency power). Neither CRP nor TNF-? were significantly related to any measure of HRV. Conclusions The finding that fibrinogen and Il-6 are moderately related to HRV suggests a link between these factors in depressed CHD patients. The relationship between autonomic nervous system function and inflammatory and coagulant processes should be investigated in larger mechanistic studies of depression and cardiac morbidity and mortality.

Carney, Robert M.; Freedland, Kenneth E.; Stein, Phyllis K.; Miller, Gregory E.; Steinmeyer, Brian; Rich, Michael W.; Duntley, Stephen P.

2007-01-01

356

Individually Coded Telemetry: a Tool for Studying Heart Rate and Behaviour in Reindeer Calves  

PubMed Central

The aim of the study was to test the performance of a silver wire modified version of the coded telemetric heart rate monitor Polar Vantage NV™ (PVNV) and to measure heart rate (HR) in a group of captive reindeer calves during different behaviour. The technical performance of PVNV HR monitors was tested in cold conditions (-30°C) using a pulse generator and the correlation between generated pulse and PVNV values was high (r = 0.9957). The accuracy was tested by comparing the HR obtained with the PVNV monitor with the standard ECG, and the correlation was significant (r = 0.9965). Both circadian HR and HR related to behavioural pattern were recorded. A circadian rhythm was observed in the HR in reindeer with a minimum during night and early morning hours and maximum at noon and during the afternoon, the average HR of the reindeer calves studied being 42.5 beats/min in February. The behaviour was recorded by focal individual observations and the data was synchronized with the output of the HR monitors. Running differed from all other behavioural categories in HR. Inter-individual differences were seen expressing individual responses to external and internal stimuli. The silver wire modified Polar Vantage NV™ provides a suitable and reliable tool for measuring heart rate in reindeer, also in natural conditions.

Eloranta, E; Norberg, H; Nilsson, A; Pudas, T; Sakkinen, H

2002-01-01

357

Effects of Moxa (Folium Artemisiae argyi) Smoke Exposure on Heart Rate and Heart Rate Variability in Healthy Young Adults: A Randomized, Controlled Human Study  

PubMed Central

Objective. To determine the effects of the moxa smoke on human heart rate (HR) and heart rate variability (HRV). Methods. Fifty-five healthy young adults were randomly divided into experimental (n = 28) and control (n = 27) groups. Experimental subjects were exposed to moxa smoke (2.5 ± 0.5?mg/m3) twice for 25 minutes in one week. ECG monitoring was performed before, during, and after exposure. Control subjects were exposed to normal indoor air in a similar environment and similarly monitored. Followup was performed the following week. Short-term (5?min) HRV parameters were analyzed with HRV analysis software. SPSS software was used for statistical analysis. Results. During and after the first exposure, comparison of percentage changes or changes in all parameters between groups showed no significant differences. During the second exposure, percentage decrease in HR, percentage increases in lnTP, lnHF, lnLF, and RMSSD, and increase in PNN50 were significantly greater in the experimental group than in control. Conclusion. No significant adverse HRV effects were associated with this clinically routine 25-minute exposure to moxa smoke, and the data suggests that short-term exposure to moxa smoke might have positive regulating effects on human autonomic function. Further studies are warranted to confirm these findings.

Cui, Yingxue; Zhao, Baixiao; Huang, Yuhai; Chen, Zhanghuang; Liu, Ping; Huang, Jian; Lao, Lixing

2013-01-01

358

Effect of changing heart rate during treatment of hypertension on incidence of heart failure.  

PubMed

An elevated heart rate (HR) at rest at baseline is associated with an increased risk of incident heart failure (HF) and with greater cardiovascular event rates in patients with chronic HF. However, despite the high attributable risk of hypertension for HF, whether the in-treatment HR predicts incident HF in patients with treated hypertension has not been evaluated. The HR was evaluated on annual electrocardiograms from 9,024 patients with hypertension without HF who were treated with losartan- or atenolol-based regimens. During a mean follow-up of 4.7 ± 1.1 years, HF developed in 285 patients (3.2%). On multivariate Cox analyses adjusted for randomized treatment, the baseline risk factors for HF, baseline and in-treatment blood pressure, QRS duration, and electrocardiographic left ventricular hypertrophy, a greater in-treatment HR predicted a 45% greater adjusted risk of new HF for every 10-beats/min increase in the HR (95% confidence interval [CI] 34% to 57%) or a 159% greater risk of HF in patients with the persistence or development of a HR of ?84 beats/min (95% CI 88% to 257%). In contrast, with adjustment for the same covariates, the baseline HR as a continuous variable was a significantly less powerful predictor of new HF (hazard ratio 1.15 per 10 beats/min, 95% CI 1.03 to 1.28) and a baseline HR of ?84 beats/min did not predict new HF (hazard ratio 1.00, 95% CI 0.63 to 1.58). In conclusion, a greater in-treatment HR on the serial electrocardiograms predicts a greater risk of incident HF during antihypertensive treatment, independent of the covariates, in patients with hypertension with electrocardiographic left ventricular hypertrophy. These findings support serial HR assessment to improve the risk stratification of patients with hypertension. PMID:22154318

Okin, Peter M; Kjeldsen, Sverre E; Julius, Stevo; Hille, Darcy A; Dahlöf, Björn; Devereux, Richard B

2012-03-01

359

The effect of gender on heart rate variability in asthmatic and normal healthy adults  

PubMed Central

Objective Low heart rate variability (HRV) has been identified as a strong predictor of a large number of diseases, reflecting the vital role of autonomic nervous system in maintaining health. It has been hypothesized that the gender differences in autonomic modulation may explain the gender differences in morbidity and/or mortality rate. This study aims to compare the autonomic balance of males with that of females based on short-term HRV analysis. Materials and Methods This cross sectional case-control study involved eighty males matched with seventy-six females. The age M±SD is 28.5±5.4 years in males and 27.3±5.6 years in females. Biocom 3000 ECG recorder was used for studying HRV. Data was analyzed using SPSS Software (v.17), screening studied variables for significant differences in the means between the groups was performed using unpaired t test. Mean heart rate (MHR) was introduced as a covariate in the statistical analysis of HRV using general linear model. Results All short-term HRV (5-min) time domain indices, total power (TP), very low frequency (VLF), low frequency (LF) and high frequency (HF) components of frequency domains were significantly higher in males except MHR, which was significantly higher in females (P<0.05 for all). Conclusion Global autonomic activity was higher in males. In contrast, females have higher heart rate compared with males.

Lutfi, Mohamed Faisal; Sukkar, Mohamed Yosif

2011-01-01

360

Heritability of submaximal exercise heart rate response to exercise training is accounted for by nine SNPs.  

PubMed

Endurance training-induced changes in hemodynamic traits are heritable. However, few genes associated with heart rate training responses have been identified. The purpose of our study was to perform a genome-wide association study to uncover DNA sequence variants associated with submaximal exercise heart rate training responses in the HERITAGE Family Study. Heart rate was measured during steady-state exercise at 50 W (HR50) on 2 separate days before and after a 20-wk endurance training program in 483 white subjects from 99 families. Illumina HumanCNV370-Quad v3.0 BeadChips were genotyped using the Illumina BeadStation 500GX platform. After quality control procedures, 320,000 single-nucleotide polymorphisms (SNPs) were available for the genome-wide association study analyses, which were performed using the MERLIN software package (single-SNP analyses and conditional heritability tests) and standard regression models (multivariate analyses). The strongest associations for HR50 training response adjusted for age, sex, body mass index, and baseline HR50 were detected with SNPs at the YWHAQ locus on chromosome 2p25 (P = 8.1 × 10(-7)), the RBPMS locus on chromosome 8p12 (P = 3.8 × 10(-6)), and the CREB1 locus on chromosome 2q34 (P = 1.6 × 10(-5)). In addition, 37 other SNPs showed P values <9.9 × 10(-5). After removal of redundant SNPs, the 10 most significant SNPs explained 35.9% of the ?HR50 variance in a multivariate regression model. Conditional heritability tests showed that nine of these SNPs (all intragenic) accounted for 100% of the ?HR50 heritability. Our results indicate that SNPs in nine genes related to cardiomyocyte and neuronal functions, as well as cardiac memory formation, fully account for the heritability of the submaximal heart rate training response. PMID:22174390

Rankinen, Tuomo; Sung, Yun Ju; Sarzynski, Mark A; Rice, Treva K; Rao, D C; Bouchard, Claude

2012-03-01

361

Non-linear heart rate control in orthostatic tolerant cosmonauts after short-duration spaceflight  

Microsoft Academic Search

Spaceflight causes changes in the cardiovascular system. These changes contribute to the occurrence of orthostatic intolerance\\u000a after spaceflight. The study of heart rate variations (HRV) provides a non-invasive means to study the autonomic modulation\\u000a of heart rate. Non-linear control mechanisms have been suggested to be involved in normal heart rate variations. Non-linear\\u000a control would be helpful in maintaining healthy cardiovascular

F Beckers; B Verheyden; K Couckuyt; AE Aubert

2007-01-01

362

Carotid artery stenting and endarterectomy have different effects on heart rate variability  

Microsoft Academic Search

ObjectiveDue to their close proximity to the carotid sinus baroreceptor region, carotid endarterectomy (CEA) and carotid angioplasty\\/stenting (CAS) carry an inherent risk of affecting baroreflex-mediated regulation of the heart rate. Variations in the heart rate can be studied by measuring heart rate variability (HRV), in which distinct frequency bands in the power spectrum represent sympathetic and parasympathetic modulations on sinus

Mehmet Demirci; Okay Sar?ba?; Kay?han Uluç; Saruhan Çekirge; Erkmen Böke; Hakan Ay

2006-01-01

363

Heart rate profiles and energy cost of locomotion during cross-country skiing races  

Microsoft Academic Search

.   The purpose of this study was to compare heart rate responses and speed in two cross-country skiing races, which were run\\u000a by seven male and seven female subjects by using classic and free style. Heart rates and skiing velocities were analyzed over\\u000a flat, uphill and downhill sections, which were run from one to three times. Heart rates were higher

Piero Mognoni; Giulio Rossi; Franco Gastaldelli; Arrigo Canclini; Francesco Cotelli

2001-01-01

364

The effect of unilateral stellectomy on the regulation of heart rate during behavioral stress  

Microsoft Academic Search

Changes in heart rate were examined during classical aversive conditioning before and after either left (n=10) or right stellectomy\\u000a (n=8). Heart rate (HR) significantly (p<0.01) increased in response to the conditional stimulus with a further increase noted\\u000a during the unconditional stimulus. After right stellectomy (RSGx) the aversive stress elicited a significantly (p<0.01) smaller\\u000a increase in heart rate (peak HR change:

George E. Billman

1992-01-01

365

A Dynamic Heart Rate Prediction Model for Training Optimization in Cycling (P83)  

Microsoft Academic Search

Heart rate can be considered as a reliable indicator of the physiological load both for immediate training monitoring and\\u000a for post-training analysis in cycling. The aim of this paper is to present a dynamic heart rate prediction model which will\\u000a be used by a model predictive controller to optimize the cycling training. This model predicts the heart rate of a

Ankang Le; Thomas Jaitner; Frank Tobias; Lothar Litz

366

Electroencephalographic and blood pressure correlates of operantly conditioned heart rate in the restrained monkey  

Microsoft Academic Search

Each of four monkeys was trained to slow its heart rate and to speed its heart rate. Mean blood pressure was positively correlated\\u000a with heart rate during speeding and during slowing. These correlations increased from early training to late training for\\u000a all animals during slowing; however, they did not change during speeding. High voltage in the 8–14 Hz band of

Bernard T. Engel

1974-01-01

367

How to correct the QT interval for the effects of heart rate in clinical studies  

Microsoft Academic Search

Much inter- and intra-subject variability in the QT interval in health and disease is accounted for by differences in heart rate, leading to difficulties when determining the effects of disease and drugs on the QT interval. Traditionally, heart rate correction formulae have been used to overcome this problem in man. However, the commonly used Bazett's heart rate correction formulae (QT=QTC?RR

Patrick Davey

2002-01-01

368

The examination of the heart rate recovery after anaerobic running in soccer players.  

PubMed

The purpose of this study was to examine the heart rate recovery depending on anaerobic running. A total of 23 professional soccer players who were player of Turkish Super Leagues, were examined. Anaerobic Run test was applied to the soccer players and their heart rates were recorded before running, just after running, in 3rd and 6th minutes of recovery period. Any statistical differences were not found between the heart rates before run and in 6th minute after run (p > 0.05). On the other hand, there was a statistical difference between the heart rates before run, after run and in 3rd minute after run; the heart rates after run and before run; the heart rates in 3rd and 6th minutes of recovery (p < 0.05). A relationship was determined between the heart rates after run, before run (r = 0.457) and in 3rd minute of recovery (r = 0.537) and the heart rates in 3rd and 6th minutes of recovery (r = 0.629). On the other hand, no relation was found between the heart rates before run, in 3rd minute recovery (r = 0.247) and in 6th minute of recovery (r = -0.004) and the heart rates just after run and in 6th minute of recovery (r = 0.280) (p > 0.05). In conclusion, even if the increase of heart rate occurring after anaerobic run doesn't completely return to normal in 3rd minute of recovery, it will supply the athlete with a suitable condition for the second loading with regard to efficient rest. It is thought that a rest over 3 minutes should be given for athletes to make the heart rate after anaerobic run return to normal. PMID:24851619

Taskin, Halil; Erkmen, Nurtekin; Cicioglu, Ibrahim

2014-03-01

369

Diurnal variations in arousal: a naturalistic heart rate study in children with ADHD  

Microsoft Academic Search

Previous studies suggest an altered circadian regulation of arousal in children with attention-deficit hyperactivity disorder\\u000a (ADHD) as measured by activity, circadian preference, and sleep-wake patterns. Although heart rate is an important measure\\u000a to evaluate arousal profiles, to date it is unknown whether 24-h heart rate patterns differentiate between children with and\\u000a without ADHD. In this study, 24-h heart rate data

Lindita Imeraj; Inge Antrop; Herbert Roeyers; Ellen Deschepper; Sarah Bal; Dirk Deboutte

370

Validity of the Polar S810 Heart Rate Monitor to Measure RR Intervals at Rest  

Microsoft Academic Search

GAMELIN, F. X., S. BERTHOIN, and L. BOSQUET. Validity of the Polar S810 Heart Rate Monitor to Measure R-R Intervals at Rest. Med. Sci. Sports Exerc., Vol. 38, No. 5, pp. 887-893, 2006. Purpose: This study was conducted to compare R-R intervals and the subsequent analysis of heart rate variability (HRV) obtained from the Polar S810 heart rate monitor (HRM)

SERGE BERTHOIN; LAURENT BOSQUET

2006-01-01

371

A comparison between computer-controlled and set work rate exercise based on target heart rate  

NASA Technical Reports Server (NTRS)

Two methods are compared for observing the heart rate (HR), metabolic equivalents, and time in target HR zone (defined as the target HR + or - 5 bpm) during 20 min of exercise at a prescribed intensity of the maximum working capacity. In one method, called set-work rate exercise, the information from a graded exercise test is used to select a target HR and to calculate a corresponding constant work rate that should induce the desired HR. In the other method, the work rate is controlled by a computer algorithm to achieve and maintain a prescribed target HR. It is shown that computer-controlled exercise is an effective alternative to the traditional set work rate exercise, particularly when tight control of cardiovascular responses is necessary.

Pratt, Wanda M.; Siconolfi, Steven F.; Webster, Laurie; Hayes, Judith C.; Mazzocca, Augustus D.; Harris, Bernard A., Jr.

1991-01-01

372

Heart rate variability, trait anxiety, and perceived stress among physically fit men and women  

Microsoft Academic Search

Background: It is unclear from prior reports whether the relationships between self-ratings of anxiety or emotional stress and parasympathetic nervous system components of heart rate variability are independent of personality and cardiorespiratory fitness. We examined those relationships in a clinical setting prior to a standardized exercise test. Methods and results: Heart rate variability (HRV) was measured during 5 min of

Rod K. Dishman; Yoshio Nakamura; Melissa E. Garcia; Ray W. Thompson; Andrea L. Dunn; Steven N. Blair

2000-01-01

373

GENETIC AND MATERNAL ENVIRONMENTAL INFLUENCES ON EMBRYONIC PHYSIOLOGY: INTRASPECIFIC VARIABILITY IN AVIAN EMBRYONIC HEART RATES  

Microsoft Academic Search

The heart rate of embryos of altricial pigeons (Columba domesticui and hank swallows (Riparia riparia) was measured on a daily basis to investigate inrerclutch versus intracl utch variabi lity in heart rate during development. In both pigeons and swallows, the developmental patterns of he an rate change in siblings (i.e., embryos from the same clutch) are statistically much more similar

W. W. BURGGRI; H. TAZAWA

374

Precision Digital Instrument for Calculation of Heart Rate and RR Interval  

Microsoft Academic Search

An economical precision digital heart rate meter has been constructed for use in general laboratory EKG studies and especially as a diagnostic aid in pacemaker clinics. The instrument features a digital method for rate computation with no calibration required, a system test feature and ability to measure and digitally display both heart rate in beats per minute (bpm) and R-R

Kenneth D. Taylor; Martin Mandelberg

1975-01-01

375

The Effect of Associative and Dissociative Attentional Focus Strategies on Muscle Activity and Heart Rate During a Weight Training Exercise  

Microsoft Academic Search

Performance outcomes, such as the distance rowed or run, can be influenced by the type of attentional focus an individual adopts. The present study tested how attentional focus during a weight training exercise influenced a direct measure of performance production (muscle activity) and heart rate. Participants (27 men, 3 women; age range 18–37 years) executed bicep curls while adopting an

David L. Neumann; Sandor Heng

2011-01-01

376

Ivabradine: a new rate-limiting therapy for coronary artery disease and heart failure  

PubMed Central

Ivabradine is a new bradycardic agent acting on the If channels of sinoatrial nodal cells to decrease the rate of diastolic depolarization and thus heart rate. The benefit of ivabradine over other negatively chronotropic agents is its absence of negative inotropy. Effective management of coronary artery disease, in terms of reducing morbidity and mortality, is reliant on controlling heart rate. Ivabradine has been shown to safely and effectively reduce heart rate without compromising cardiac function in patients with coronary artery disease and more recently in patients with heart failure and raised heart rate. Furthermore, ivabradine has been shown to have a favourable side-effect profile compared with alternative bradycardic agents. This article reviews the evidence for ivabradine in coronary artery disease and heart failure and compares its safety with alternative bradycardic agents for these conditions.

Rushworth, Gordon F.; Lambrakis, Philippe

2011-01-01

377

Effect of heart rate correction on pre- and post-exercise heart rate variability to predict risk of mortality--an experimental study on the FINCAVAS cohort  

PubMed Central

The non-linear inverse relationship between RR-intervals and heart rate (HR) contributes significantly to the heart rate variability (HRV) parameters and their performance in mortality prediction. To determine the level of influence HR exerts over HRV parameters' prognostic power, we studied the predictive performance for different HR levels by applying eight correction procedures, multiplying or dividing HRV parameters by the mean RR-interval (RRavg) to the power 0.5–16. Data collected from 1288 patients in The Finnish Cardiovascular Study (FINCAVAS), who satisfied the inclusion criteria, was used for the analyses. HRV parameters (RMSSD, VLF Power and LF Power) were calculated from 2-min segment in the rest phase before exercise and 2-min recovery period immediately after peak exercise. Area under the receiver operating characteristic curve (AUC) was used to determine the predictive performance for each parameter with and without HR corrections in rest and recovery phases. The division of HRV parameters by segment's RRavg to the power 2 (HRVDIV-2) showed the highest predictive performance under the rest phase (RMSSD: 0.67/0.66; VLF Power: 0.70/0.62; LF Power: 0.79/0.65; cardiac mortality/non-cardiac mortality) with minimum correlation to HR (r = ?0.15 to 0.15). In the recovery phase, Kaplan-Meier (KM) survival analysis revealed good risk stratification capacity at HRVDIV-2 in both groups (cardiac and non-cardiac mortality). Although higher powers of correction (HRVDIV-4and HRVDIV-8) improved predictive performance during recovery, they induced an increased positive correlation to HR. Thus, we inferred that predictive capacity of HRV during rest and recovery is augmented when its dependence on HR is weakened by applying appropriate correction procedures.

Pradhapan, Paruthi; Tarvainen, Mika P.; Nieminen, Tuomo; Lehtinen, Rami; Nikus, Kjell; Lehtimaki, Terho; Kahonen, Mika; Viik, Jari

2014-01-01

378

The effects of in utero cocaine-exposure on the heart rate and heart rate variability of near and full term infants following orthostatic stress  

Microsoft Academic Search

To understand the effects of in utero cocaine exposure on the developing fetus, we studied the heart rate and the heart rate variability (HRV) in near and full term cocaine-exposed infants during quiet sleep supine and following orthostatic stress. 21 cocaine-exposed and 23 control infants were studied within 120 hours of birth. 30-minute segments of the electrocardiogram (ECG) were recorded

V. John; A. Talati; H. Bada

2002-01-01

379

The effects of in utero cocaine-exposure on the heart rate and heart rate variability of near and full term infants following orthostatic stress  

Microsoft Academic Search

To understand the effects of in utero cocaine exposure on the developing fetus, we studied the heart rate and the heart rate variability in near and full term cocaine-exposed infants in quiet sleep supine and following orthostatic stress. We studied 21 cocaine-exposed and 23 control infants within 120 hours of birth. Two 30-minute segments of the electrocardiogram (ECG) were recorded

V. John; M. R. Neuman; A. J. Talati

2002-01-01

380

Cardiac autonomic functions derived from short-term heart rate variability recordings associated with heart rate recovery after treadmill exercise test in young individuals  

Microsoft Academic Search

Analysis of short-term heart rate variability (HRV) may provide useful information about autonomic nervous control of heart\\u000a rate recovery. We studied 495 individuals (273 men), age range 19–85 years, submitted to treadmill exercise tests and short-term\\u000a HRV evaluations over time (standard deviation of the normal-to-normal interval [SDNN], the square root of the mean squared\\u000a differences of successive normal-to-normal intervals [RMSSD],

Ju-Yi Chen; Yungling Leo Lee; Wei-Chuan Tsai; Cheng-Han Lee; Po-Sheng Chen; Yi-Heng Li; Liang-Miin Tsai; Jyh-Hong Chen; Li-Jen Lin

2011-01-01

381

Detection of changes in the fractal scaling of heart rate and speed in a marathon race  

NASA Astrophysics Data System (ADS)

The aim of this study was to detect changes in the fractal scaling behavior of heart rate and speed fluctuations when the average runner’s speed decreased with fatigue. Scaling analysis in heart rate (HR) and speed (S) dynamics of marathon runners was performed using the detrended fluctuation analysis (DFA) and the wavelet based structure function. We considered both: the short-range ( ?1) and the long-range ( ?2) scaling exponents for the DFA method separated by a change-point, n0=64=5.3 min (box length), the same for all the races. The variability of HR and S decreased in the second part of the marathon race, while the cardiac cost time series (i.e. the number of cardiac beats per meter) increased due to the decreasing speed behavior. The scaling exponents ?1 and ?2 of HR and ?1 of S, increased during the race ( p<0.01) as did the HR wavelet scaling exponent ( ?). These findings provide evidence of the significant effect of fatigue induced by long exercise on the heart rate and speed variability.

Billat, Véronique L.; Mille-Hamard, Laurence; Meyer, Yves; Wesfreid, Eva

2009-09-01

382

Computer Software tool for heart rate variability (HRV), T-wave alternans (TWA) and heart rate turbulence (HRT) analysis from ECGs  

PubMed Central

Summary Background This paper presents a software package for quantitative evaluation of heart rate variability (HRV), heart rate turbulence (HRT), and T-wave alternans (TWA) from ECG recordings. The software has been developed for the purpose of scientific research rather than clinical diagnosis. Material/Methods The software is written in Matlab Mathematical Language. Procedures for evaluation of HRV, HRT and TWA were implemented. HRV analysis was carried out by applying statistical and spectral parametric and nonparametric methods. HRT parameters were derived using the Schmidt algorithm. TWA analysis was performed both in spectral and in time domain by applying Poincare mapping. A flexibility of choosing from a number of classical modelling approaches and their modifications was foreseen and implemented. The software underwent preliminary verification tests both on ECGs from the Physionet online ECG signal repository and recordings taken at the Department of Electrocardiology of the Medical University Hospital in Lodz. Results The result of the research is a program enabling simultaneous analysis of a number of parameters computed from ECG recordings with the use of the indicated analysis methods. The program offers options to preview the intermediate results and to alter the preprocessing steps. Conclusions By offering the possibility to cross-validate the results of analyses obtained by several methods and to preview the intermediate analysis steps, the program can serve as a helpful aid for clinicians in comprehensive research studies. The software tool can also be utilized in training programs for students and medical personnel.

Kudrynski, Krzysztof; Strumillo, Pawel; Ruta, Jan

2011-01-01

383

Heart Rate And Blood Lactate Responses To Changquan And Daoshu Forms Of Modern Wushu  

PubMed Central

The development of specific training designed to enhance physiological aspects of performance relies heavily on the availability of accurate and validity physiological data. In the combat sport of Wushu, katas are used to develop aerobic fitness. It is arguably important to assess and monitor heart rate (HR) and lactate (La) responses when designing effective training programs. The aim of this pilot study was to investigate heart rate and lactate responses to forms execution among Wushu combatants. Male elite modern Wushu athletes (n = 4) from a South Brazilian regional team participated in the study. Athletes were aged 22.5 ± 2.08 years old and had at least eight years of Wushu experience. Athletes carried out the Changquan and Daoshu forms in random order, HR and La were measured pre- and post-exercise. Results indicate that HR was 176 ± 3 and 176 ± 2 bpm and La was 4.38 ± 1.3 and 5.15 ± 1.07 mmol·l-1 for Changquan and Daoshu forms, respectively. There were no significantly differences in HR and La between the two forms. HR values represent 89.2 ± 1.1 and 89.1 ± 1.8% of age-predicted maximal heart rate and lactate was near of 4 mmol·l-1 point. In conclusion, training programs to Wushu combatants could target the range of physiological values cited above with no differences between two forms. Key Points Heart rate and lactate responses are not significantly different between Changquan and Daoshu forms for Wushu combatants. The Wushu katas could be used to develop aerobic fitness.

Ribeiro, Jerri Luiz; de Castro, Bruno Ogoday S. D.; Rosa, Caio S.; Baptista, Rafael R.; Oliveira, Alvaro R.

2006-01-01

384

Heart rate variability in type 2 diabetes mellitus.  

PubMed

Heart rate variability (HRV) is a noninvasive measure of cardiac autonomic modulation. Time and frequency domain measures have primarily been examined in patients with type 2 diabetes mellitus (T2D). Not only do frequency domain HRV parameters tend to be reduced in T2D, but healthy individuals with low HRV are also more likely to develop T2D. Furthermore, patients with T2D with low HRV have an increased prevalence of complications and risk of mortality compared with those with normal autonomic function. These findings provide support for the use of HRV as a risk indicator in T2D. Exercise is considered an important component to T2D prevention and treatment strategies. To date, few studies have examined the changes in HRV with exercise in T2D. One study showed changes in resting HRV, two studies showed changes in HRV during or following acute stressors, and one study showed no changes in HRV but improvements in baroreflex sensitivity. The most pronounced changes in HRV were realized following the exercise intervention with the greatest frequency of supervised exercise sessions and with the greatest intensity and duration of exercise bouts. These findings suggest that exercise following current American College of Sports Medicine/American Diabetes Association guidelines may be important in the prevention and treatment of T2D to improve autonomic function and reduce the risk of complications and mortality. PMID:24580567

Stuckey, Melanie I; Petrella, Robert J

2013-01-01

385

Heart rate variability in patients with untreated Parkinson's disease.  

PubMed

The aim of this study was to evaluate cardiovascular responses as a marker of autonomic nervous system (ANS) disturbances in patients with untreated Parkinson's disease (PD) and to assess the relationship between them and the clinical characteristics of PD. The ANS functions were investigated in 50 patients with PD and 55 healthy subjects by measuring standard cardiovascular autonomic reflexes and heart rate variability (HRV) at rest using spectral analysis (the autoregressive model and the fast Fourier transformation), the percentage of the counts of beat-to-beat variation greater than 50 ms and the fractal dimension. Significantly attenuated HRV and deficient blood pressure reaction to tilting were found in the PD patient group. The patients with hypokinesia/rigidity as the initial symptom of PD had a more pronounced HRV deficit than those with tremor onset. Untreated PD patients suffer significant failure in cardiovascular nervous system regulation, and in patients with hypokinesia/rigidity as their initial disease manifestation the risk of this ANS dysfunction is high. However, in the early stages of PD these changes did not reach significance at individual level. PMID:11136353

Kallio, M; Haapaniemi, T; Turkka, J; Suominen, K; Tolonen, U; Sotaniemi, K; Heikkilä, V P; Myllylä, V

2000-11-01

386

Heart-rate monitoring by air pressure and causal analysis  

NASA Astrophysics Data System (ADS)

Among lots of vital signals, heart-rate (HR) is an important index for diagnose human's health condition. For instance, HR provides an early stage of cardiac disease, autonomic nerve behavior, and so forth. However, currently, HR is measured only in medical checkups and clinical diagnosis during the rested state by using electrocardiograph (ECG). Thus, some serious cardiac events in daily life could be lost. Therefore, a continuous HR monitoring during 24 hours is desired. Considering the use in daily life, the monitoring should be noninvasive and low intrusive. Thus, in this paper, an HR monitoring in sleep by using air pressure sensors is proposed. The HR monitoring is realized by employing the causal analysis among air pressure and HR. The causality is described by employing fuzzy logic. According to the experiment on 7 males at age 22-25 (23 on average), the correlation coefficient against ECG is 0.73-0.97 (0.85 on average). In addition, the cause-effect structure for HR monitoring is arranged by employing causal decomposition, and the arranged causality is applied to HR monitoring in a setting posture. According to the additional experiment on 6 males, the correlation coefficient is 0.66-0.86 (0.76 on average). Therefore, the proposed method is suggested to have enough accuracy and robustness for some daily use cases.

Tsuchiya, Naoki; Nakajima, Hiroshi; Hata, Yutaka

2011-05-01

387

Heart rate & blood lactate response in field hockey players.  

PubMed

The heart rate and blood lactate were studied in field hockey players (25 juniors and 29 seniors) as well as the blood lactate response in training to assess the anaerobic demand of the game and the adaptability of the players to anaerobic metabolism, respectively. The mean VO2 max of the junior and senior players were 3.32 l/min (54.4 ml/kg/min) and 3.28 l/min (53.8 ml/kg/min), respectively. Blood lactate levels after warm up, training and the game were 2.1, 7.4 and 4.2 mM/l, respectively for the juniors and 2.6, 7.7 and 5.6 mM/l, for the seniors. The aerobic capacity (VO2 max) of the juniors did not differ from their senior counterparts, indicating a similar adaptability to aerobic metabolism. However, the Indian players revealed a lower VO2 max than their International counterparts. Similar lactate levels in juniors and seniors after training indicated a similar adaptability to the anaerobic metabolism also. The higher blood lactate level in seniors after the game reflected that they played with greater intensity than the juniors, due to more experience, better motivation and skill. PMID:1794891

Ghosh, A K; Goswami, A; Mazumdar, P; Mathur, D N

1991-10-01

388

Kubios HRV--heart rate variability analysis software.  

PubMed

Kubios HRV is an advanced and easy to use software for heart rate variability (HRV) analysis. The software supports several input data formats for electrocardiogram (ECG) data and beat-to-beat RR interval data. It includes an adaptive QRS detection algorithm and tools for artifact correction, trend removal and analysis sample selection. The software computes all the commonly used time-domain and frequency-domain HRV parameters and several nonlinear parameters. There are several adjustable analysis settings through which the analysis methods can be optimized for different data. The ECG derived respiratory frequency is also computed, which is important for reliable interpretation of the analysis results. The analysis results can be saved as an ASCII text file (easy to import into MS Excel or SPSS), Matlab MAT-file, or as a PDF report. The software is easy to use through its compact graphical user interface. The software is available free of charge for Windows and Linux operating systems at http://kubios.uef.fi. PMID:24054542

Tarvainen, Mika P; Niskanen, Juha-Pekka; Lipponen, Jukka A; Ranta-Aho, Perttu O; Karjalainen, Pasi A

2014-01-01

389

Estimation of human core temperature from sequential heart rate observations.  

PubMed

Core temperature (CT) in combination with heart rate (HR) can be a good indicator of impending heat exhaustion for occupations involving exposure to heat, heavy workloads, and wearing protective clothing. However, continuously measuring CT in an ambulatory environment is difficult. To address this problem we developed a model to estimate the time course of CT using a series of HR measurements as a leading indicator using a Kalman filter. The model was trained using data from 17 volunteers engaged in a 24 h military field exercise (air temperatures 24-36 °C, and 42%-97% relative humidity and CTs ranging from 36.0-40.0 °C). Validation data from laboratory and field studies (N = 83) encompassing various combinations of temperature, hydration, clothing, and acclimation state were examined using the Bland-Altman limits of agreement (LoA) method. We found our model had an overall bias of -0.03 ± 0.32 °C and that 95% of all CT estimates fall within ±0.63 °C (>52 000 total observations). While the model for estimating CT is not a replacement for direct measurement of CT (literature comparisons of esophageal and rectal methods average LoAs of ±0.58 °C) our results suggest it is accurate enough to provide practical indication of thermal work strain for use in the work place. PMID:23780514

Buller, Mark J; Tharion, William J; Cheuvront, Samuel N; Montain, Scott J; Kenefick, Robert W; Castellani, John; Latzka, William A; Roberts, Warren S; Richter, Mark; Jenkins, Odest Chadwicke; Hoyt, Reed W

2013-07-01

390

A new ex vivo beating heart model to investigate the application of heart valve performance tools with a high-speed camera.  

PubMed

High-speed camera examination of heart valves is an established technique to examine heart valve prosthesis. The aim of this study was to examine the possibility to transmit new tools for high-speed camera examination of heart valve behavior under near-physiological conditions in a porcine ex vivo beating heart model. After explantation of the piglet heart, main coronary arteries were cannulated and the heart was reperfused with the previously collected donor blood. When the heart started beating in sinus rhythm again, the motion of the aortic and mitral valve was recorded using a digital high-speed camera system (recording rate 2,000 frames/sec). The image sequences of the mitral valve were analyzed, and digital kymograms were calculated at different angles for the exact analysis of the different closure phases. The image sequence of the aortic valve was analyzed, and several snakes were performed to analyze the effective orifice area over the time. Both processing tools were successfully applied to examine heart valves in this ex vivo beating heart model. We were able to investigate the exact open and closure time of the mitral valve, as well as the projected effective orifice area of the aortic valve over the time. The high-speed camera investigation in an ex vivo beating heart model of heart valve behavior is feasible and also reasonable because of using processing feature such as kymography for exact analysis. These analytical techniques might help to optimize reconstructive surgery of the mitral valve and the development of heart valve prostheses in future. PMID:24270227

Kondruweit, Markus; Friedl, Sven; Heim, Christian; Wittenberg, Thomas; Weyand, Michael; Harig, Frank

2014-01-01

391

Effects of Particulate Air Pollution on Blood Pressure and Heart Rate in Subjects with Cardiovascular Disease: A Multicenter Approach  

Microsoft Academic Search

Given the hypothesis that air pollution is associated with elevated blood pressure and heart rate, the effect of daily concentrations of air pollution on blood pressure and heart rate was assessed in 131 adults with coronary heart disease in Helsinki, Finland; Erfurt, Germany; and Amsterdam, the Netherlands. Blood pressure was measured by a digital monitor, and heart rate was calculated

Angela Ibald-Mulli; Kirsi L. Timonen; Annette Peters; Joachim Heinrich; Gabriele Wölke; Timo Lanki; Gintautas Buzorius; Wolfgang G. Kreyling; Jeroen de Hartog; Gerard Hoek; Harry M. ten Brink; Juha Pekkanen

2003-01-01

392

Embryonic heart rate and oxygen pulse in two procellariiform seabirds, Diomedea immutabilis and Puffinus pacificus  

Microsoft Academic Search

Developmental patterns of embryonic heart rate were measured non-invasively in two procellariiform seabirds, the Laysan albatross (Diomedea immutabilis) and wedge-tailed shearwater (Puffinus pacificus), during prepipping and after pipping. The O2 pulse, defined as the O2 consumption per single heart beat, was calculated using the previously reported O2 consumption for these species. The embryonic heart rate of the albatross was not

H. Tazawa; G. Causey Whittow

1994-01-01

393

Computer modeling of nonlinear heart rate dynamics during train extracardial impulsation in the sinoatrial node  

Microsoft Academic Search

A computer model of excitation conduction in the heart has been employed to study the nonlinear heart rate dynamics under\\u000a stress loads. The modeling was aimed to test the hypothesis explaining changes in the heart rate dynamics during nociceptive\\u000a stress loads by the occurrence of train extracardial impulsation arriving at the sinoatrial node. The computer simulation\\u000a shows that, with a

L. V. Mezentseva

2011-01-01

394

Development of a piezopolymer pressure sensor for a portable fetal heart rate monitor  

NASA Technical Reports Server (NTRS)

A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.

Zuckerwar, A. J.; Pretlow, R. A.; Stoughton, J. W.; Baker, D. A.

1993-01-01

395

[The analysis of heart rate variability as non-invasive method of cardiovascular system assessment].  

PubMed

Heart rate variability (HRV) is estimated using time and frequency method. This analysis allows a non-invasive assessment of both the heart and autonomic nervous system. The usefulness of HRV estimation has been confirmed in patients not only with diabetic neuropathy, tetraplegia, various heart diseases (after heart transplantation, with heart failure, after myocardial infarction, with hypertrophic and dilated cardiomyopathy, with cardiological syndrome X and with arrhythmia), but also with thyroid gland diseases and in physiological states of human being. The described information indicate a wide range and increasing usefulness of HRV analysis in medical studies. PMID:11816300

Jagodzi?ski, L; Siela?czyk, A; Ciesió?ka, A; Gmyrek, J; Niepsuj, K

2001-01-01

396

HEART RATE, RESPIRATORY FREQUENCY AND WING BEAT FREQUENCY OF FREE FLYING BARNACLE GEESE BRANTA LEUCOPSIS  

Microsoft Academic Search

SUMMARY 1. Two barnacle geese (Branta leucopsis) were successfully imprinted on a human and encouraged to fly behind an open-topped truck containing the foster parent. A two channel radio-transmitter was implanted into these geese so that heart rate and respiratory frequency could be recorded before, during and after flights of relatively long duration. The resting value for heart rate was

P. J. BUTLER; A. J. WOAKES

397

The influence of ventilatory control on heart rate variability in children  

Microsoft Academic Search

The aim of this study was to determine the influence of breathing frequency and tidal volume on resting heart rate variability in children aged 9 years ( n = 29) and 16 years ( n = 19). Heart rate variability was measured in four conditions: (1) without the control of ventilation followed at random by (2) a fixed breathing frequency

Craig A. Williams; Philippe Lopes

2002-01-01

398

Power spectrum of heart rate variability in exercising humans: The effect of exercise intensity  

Microsoft Academic Search

Power spectral analysis of heart rate variability (HRV) has been estimated by means of a Fourier transform method at rest in seven healthy men and three women, during a 30?minutes steady state cycle exercise test at 40%, 50%, 60%, 70% and 80% respectively, of maximal heart rate reserve (MHRR) defined as (HRmax ? HRrest). Total power (PT) of HRV was

Pavel Stejskal; Jana Rechbergová; Jirí Salinger; Radim Šlachta; Milan Elfmark; Martn Kalina; Radim Jur?a; Iva Rehová

2001-01-01

399

Telemetric measuring system for the diagnostics of heart rate variability-VariaPulse TF  

Microsoft Academic Search

Summary form only given. Heart rate variability (HRV) is an important marker in the diagnostics of some diseases associated with autonomic nervous system (ANS) dysfunctions. One of the advanced methods is the spectral analysis of heart rate variations (SAHRV). Early diagnosis of ANS disfunction is very important from the point of view of prevention and subsequent therapy. This fact served

R. Vychodil; J. Sabinger; J. Novotny

1997-01-01

400

Heart rate turbulence and left ventricular ejection fraction in Chagas disease  

Microsoft Academic Search

Aims Chagas disease patients often present premature ventricular complexes (PVCs), depression of left ventricular ejection fraction (LVEF) and autonomic dysfunction, which is generally evaluated by heart rate variability (HRV) analysis. As frequent PVCs may complicate HRV computation, we measured heart rate turbulence (HRT) and evaluated the correlation between ejection fraction and HRT or HRV in Chagas disease. Methods We studied

Fabrizio Tundo; Federico Lombardi; Manoel C. Rocha; Fernando Botoni; Georg Schmidt; Vladimir C. Barros; Braulio Muzzi; Murilo Gomes; Airandes Pinto; Antonio L. Ribeiro

2005-01-01

401

Heart rate turbulence and left ventricular ejection fraction in Chagas disease  

Microsoft Academic Search

AimsChagas disease patients often present premature ventricular complexes (PVCs), depression of left ventricular ejection fraction (LVEF) and autonomic dysfunction, which is generally evaluated by heart rate variability (HRV) analysis. As frequent PVCs may complicate HRV computation, we measured heart rate turbulence (HRT) and evaluated the correlation between ejection fraction and HRT or HRV in Chagas disease.

Fabrizio Tundo; Federico Lombardi; Manoel C. Rocha; Fernando Botoni; Georg Schmidt; Vladimir C. Barros; Braulio Muzzi; Murilo Gomes; Airandes Pinto; Antonio L. Ribeiro

2005-01-01

402

The Influence of Motor Impairment on Autonomic Heart Rate Modulation among Children with Cerebral Palsy  

ERIC Educational Resources Information Center

The study of heart rate variability is an important tool for a noninvasive evaluation of the neurocardiac integrity. The present study aims to evaluate the autonomic heart rate modulation in supine and standing positions in 12 children diagnosed with cerebral palsy and 16 children with typical motor development (control group), as well as to…

Zamuner, Antonio Roberto; Cunha, Andrea Baraldi; da Silva, Ester; Negri, Ana Paola; Tudella, Eloisa; Moreno, Marlene Aparecida

2011-01-01

403

Effects of head-down bed rest on complex heart rate variability: Response to LBNP testing  

NASA Technical Reports Server (NTRS)

Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 deg head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on a 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal 'complexity' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ('chaos theory'), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.

Goldberger, Ary L.; Mietus, Joseph E.; Rigney, David R.; Wood, Margie L.; Fortney, Suzanne M.

1994-01-01

404

Short-term analysis of heart-rate variability of adapted wavelet transforms  

Microsoft Academic Search

The purpose of this study is to characterize the heart rate variability (HRV) signal in the frequency domain by using wavelet and cosine packets. Here, the authors introduce the adapted wavelet transform methods to analyze heart-rate fluctuations. These methods were chosen because the components in the signals can be analyzed and quantified at different scales, e.g., long windows can be

U. Wiklund; M. Akay; U. Niklasson

1997-01-01

405

Heart rate variability: sleep stage, time of night, and arousal influences  

Microsoft Academic Search

Spectral analysis was used to assess heart rate variability in consecutive 5-min epochs during the night in 12 normal adults. Simultaneous time coding of EEG and digitized EKG allowed examination of heart rate variability as a function of sleep stage, time of night and presence of EEG arousal. The results replicated previous studies in showing increases in high frequency components

M. H. Bonnet; D. L. Arand

1997-01-01

406

Decreased heart rate variability in survivors of sudden cardiac death not associated with coronary artery disease  

Microsoft Academic Search

BACKGROUND--Although heart rate variability has already been studied in survivors of sudden cardiac death secondary to coronary artery disease, an assessment of heart rate variability in survivors of sudden cardiac death not associated with coronary artery disease has not been made. METHODS--10 patients with aborted sudden cardiac death not associated with coronary artery disease (seven patients with primary ventricular fibrillation

J Singh; M. H. Anderson; D. Katritsis; J. Sneddon; D. J. Statters; M. Malik; A. J. Camm

1994-01-01

407

Electroencephalogram and Heart Rate Regulation to Familiar and Unfamiliar People in Children with Autism Spectrum Disorders  

ERIC Educational Resources Information Center

Few studies have examined whether familiarity of partner affects social responses in children with autism. This study investigated heart rate regulation (respiratory sinus arrhythmia [RSA]: The myelinated vagus nerve's regulation of heart rate) and temporal-parietal electroencephalogram (EEG) activity while nineteen 8- to 12-year-old children with…

Van Hecke, Amy Vaughan; Lebow, Jocelyn; Bal, Elgiz; Lamb, Damon; Harden, Emily; Kramer, Alexis; Denver, John; Bazhenova, Olga; Porges, Stephen W.

2009-01-01

408

Cardiac Autonomic Regulation under Hypnosis Assessed by Heart Rate Variability: Spectral Analysis and Fractal Complexity  

Microsoft Academic Search

Objective: This study examined the effects of hypnosis on autonomic cardiac control. We hypothesized a modification of autonomic modulation of the heart rate with an enhanced vagal tone during hypnosis compared to baseline. Methods: In 12 healthy subjects (6 men and 6 women, 22.2 ± 1.0 years of age) ECG was recorded at baseline and during hypnosis. Heart rate variability

André E. Aubert; Bart Verheyden; Frank Beckers; Jan Tack; Joris Vandenberghe

2009-01-01

409

Development of a portable fetal and maternal heart rate recorder for 24 hours  

Microsoft Academic Search

This paper focuses on developing an ambulatory system capable of monitoring the fetal heart rate (FHR) as well as recording the FHR and maternal heart Rate (MHR) for 24 hours by two-development work. The first is a microcontroller board which uses three electrodes, to sense the abdominal electrocardiogram (AECG) signals and then process the signal for monitoring FHR and recording

Firoz Ahmed; Mohd Alauddin Mohd Ali; Edmond Zahedi

2000-01-01

410

Blunted Heart Rate Dip During Sleep and All-Cause Mortality  

Microsoft Academic Search

Background: Although it has been somewhat over- looked, resting heart rate is an established predictor of cardiovascular and noncardiovascular outcome. We as- sessed the determinants and mortality associations of heart rate measured during ambulatory blood pressure moni- toring (ABPM) to evaluate its informativeness during ac- tivity and sleep. Methods: We studied a cohort of 3957 patients aged 55 ±1 6

Iddo Z. Ben-Dov; Jeremy D. Kark; Drori Ben-Ishay; Judith Mekler; Liora Ben-Arie; Michael Bursztyn

2007-01-01

411

Assessment of autonomic regulation to heart rate variability by the method of complex demodulation  

Microsoft Academic Search

Complex demodulation of heart-rate variability was used to analyze changes in the autonomic regulation of dog heart rate during differential classical conditioning before and after autonomic blockade. This method tracked the rapid withdrawal of parasympathetic tone following the onset of the warning signal and detected a later rise in low-frequency power that was tentatively identified as a sympathetic increase. Results

S. Shin; S. S. Reisman; W. N. Tapp; B. H. Natelson

1988-01-01

412

Review of the Validity of National Coronary Heart Disease Mortality Rates  

Microsoft Academic Search

Epidemiologic studies of coronary heart disease are heavily dependent on national mortality rates. The diagnostic error for the coronary heart disease is substantial but unquantifiable and is conservatively at least ± 30%. When this error is superimposed on innumerable errors and omissions in the compilation of monocausal mortality rates, the reliability of such vital statistics currently precludes their use for

William E. Stehbens

1990-01-01

413

Exercise heart rates at different serum digoxin concentrations in patients with atrial fibrillation  

Microsoft Academic Search

Heart rate at rest and during increasing workloads was measured in a double blind study of 12 patients with chronic atrial fibrillation when serum concentrations of digoxin were nil and at low and high therapeutic values. Twelve normal subjects were studied for comparison. The heart rate at all levels of exercise in most patients with atrial fibrillation was not adequately

R Beasley; D A Smith; D J McHaffie

1985-01-01

414

Model-based nonlinear control of the human heart rate during treadmill exercising  

Microsoft Academic Search

We study a recently-proposed nonlinear model for human heart rate response that describes the central and peripheral local responses during and after treadmill exercise. The treadmill speed is the control input, and the control objective is to make the heart rate track a prescribed reference trajectory. Using a strict Lyapunov function analysis, we design new state and output feedback tracking

Frédéric Mazenc; Michael Malisoff; Marcio S. de Queiroz

2010-01-01

415

Extraction of underlying genuine heart rate variability using adaptive signal canceling algorithm  

Microsoft Academic Search

This paper proposes a method for extracting underlying genuine heart rate fluctuations, separating them from distinct respiratory and blood pressure originating fluctuations. Heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from nine normal subjects aged from 20-24 years old. A signal cancellation scheme together with the adaptive RLS algorithm has been applied to the data

K. Yana; Hirohisa Mizuta; Osamu Tsuda; Yoshiyuki Kikuchi

1998-01-01

416

Salivary THC following cannabis smoking correlates with subjective intoxication and heart rate  

Microsoft Academic Search

A cannabis smoking trial was conducted using paid volunteers. Subjective intoxication, measured using a visual analogue scale, was compared with heart rate and with salivary delta-9-tetrahydrocannabinol (THC) levels at various times after smoking a cigarette containing 11 mg THC. Subjective intoxication and heart rate elevation were significantly correlated with the log of salivary THC. Salivary THC levels are a sensitive

David B. Menkes; Richard C. Howard; George F. S. Spears; Eric R. Cairns

1991-01-01

417

Effects of Biofeedback Training on Voluntary Heart Rate Control During Dynamic Exercise  

Microsoft Academic Search

The aims of this study were to (1) compare the effect of biofeedback with that of verbal instructions on the control of heart rate during exercise on a treadmill, (2) test the possible effect of workload on this control, and (3) examine the effect of workload on baseline heart rate at rest and during exercise. The study involved 35 participants

Maria Álvarez Moleiro; Francisco Villamarín Cid

2001-01-01

418

The relationship between power output and heart rate in ducks diving voluntarily  

Microsoft Academic Search

Heart rate in response to natural and induced changes in power output was monitored in ducks diving voluntarily to a depth of 1.2 m. Adult lesser scaup (Aythya affinis) (3 female, 2 male), were trained to make shallow dives in an indoor tank (1.2 m depth) to obtain food. Heart rate was monitored using telemetry, and was determined for the

Lowell T. McPhail; David R. Jones

1998-01-01

419

Effect of exercise training on heart rate variability in healthy older adults  

Microsoft Academic Search

Objective To determine the effect of exercise training on cardiac autonomic modulation in normal older adults by using analysis of heart rate variability. Subjects The exercise group consisted of 7 men and 9 women aged 66 ± 4 years. The comparison group consisted of 7 men and 9 women also aged 66 ± 4 years. Method Heart rate variability was

Phyllis K. Stein; Ali A. Ehsani; Peter P. Domitrovich; Robert E. Kleiger; Jeffrey N. Rottman

1999-01-01

420

A comparison of different heart rate deflection methods to predict the anaerobic threshold  

Microsoft Academic Search

There is perhaps no greater controversy in exercise physiology than the validity, or lack thereof, of the heart rate breakpoint theory in general, and the Conconi test in particular, in assessing the anaerobic threshold. Three heart rate breakpoint methods have been proposed as methods of detecting the anaerobic threshold have appeared in the literature: (1) a breakpoint in linearity of

Daniel G. Carey; German J. Pliego; Robert L. Raymond

2008-01-01

421

HEART-RATE RECOVERY IMMEDIATELY AFTER EXERCISE AS A PREDICTOR OF MORTALITY  

Microsoft Academic Search

A BSTRACT Background The increase in heart rate that accom- panies exercise is due in part to a reduction in vagal tone. Recovery of the heart rate immediately after exercise is a function of vagal reactivation. Because a generalized decrease in vagal activity is known to be a risk factor for death, we hypothesized that a de- layed fall in

C HRISTOPHER R. C OLE; E UGENE H. B LACKSTONE; J. P ASHKOW; C LAIRE E. S NADER; S. L AUER

2010-01-01

422

[Heart rate of anaesthesiologists under physical and psychological professional stress (author's transl)].  

PubMed

The heart rate of anaesthesiologists under defined physical and psychological stress as well as during normal anaesthetic practice was studied. An acceleration of heart rate during induction and management of anaesthesia did not occur except in the presence of complicating circumstances. A phone call or a beeper alarm led to a rather ergotropic heart rate reaction (increase of 21%), especially when sleep was interrupted (increase of 75%). Locomotion for a professional reason, whether urgent or not, enhanced the heart rate up to 121/min. A simultaneous subjective feeling of psychological stress had no additional effect. The heart rate during the treatment of life-threatening situations remained at 109/min and often exceeded that of exhaustive running. The mean heart rate during the normal narcotic programe (90/min) was not uncommon and comparable with that of other surgical disciplines. However an increasing tolerance was seen with growing experience. Physical and psychological stress during the anaesthesiologist's work could be differentiated by means of heart rate except in some single observations. In the presence of both stressing factors the heart rate seems to be determined by the motor effort required. PMID:907071

Lazarus, G; Weis, K H

1977-08-01

423

Wireless Monitoring of Heart Rate and Electromyographic Signals using a Smart T-shirt  

Microsoft Academic Search

We have developed a prototype T-shirt with integrated electrodes for wireless monitoring of heart rate and muscular activity. Monitoring of heart rate is insensitive to the actual placement of the textile sensors by recording ECG from many positions of the trunk: This approach reduces the risk of data loss due to problems in a single channel. A multi-channel heartbeat detector

J. Stefan Karlsson; Urban Wiklund; Lena Berglin; Nils Östlund; Marcus Karlsson; Tomas Bäcklund; Kaj Lindecrantz; Leif Sandsjö

424

Changes in extracellular muscle volume affect heart rate and blood pressure responses to static exercise  

NASA Astrophysics Data System (ADS)

To investigate the effect of ?g-induced peripheral extracellular fluid reductions on heart rate and blood pressure during isometric exercise, six healthy male subjects performed three calf ergometer test with different extracellular volumes of working muscles. In all tests, body positions during exercise were identical (supine with the knee joint flexed to 900). After a pre-exercise period of 25 min, during which calf volumes were manipulated, subjects had to counteract an external force of 180 N for 5 min. During the pre-exercise period three different protocols were applied. Test A: Subjects rested in the exercise position; test B: Body position was the same as in A but calf volume was increased by venous congestion (cuffs inflated to 80 mm Hg); test C: Calf volumes were decreased by a negative hydrostatic pressure (calves about 40 cm above heart level with the subjects supine). To clamp the changed calf volumes in tests B and C, cuffs were inflated to 300 mm Hg 5 min before the onset of exercise. This occlusion was maintained until termination of exercise. Compared to tests A and B, the reduced volume of test C led to significant increases in heart rate and blood pressure during exercise. Oxygen uptake did not exceed resting levels in B and C until cuffs were deflated, indicating that exclusively calf muscles contributed to the neurogenic peripheral drive. It is concluded that changes in extracellular muscle volume have to be taken into account when comparing heart rate and blood pressure during lg- and ?g- exercise.

Baum, K.; Essfeld, D.; Stegemann, J.

425

Peripheral oxygen saturation, heart rate, and blood pressure during dental treatment of children with cyanotic congenital heart disease  

PubMed Central

OBJECTIVES: In this observational study, we evaluated the peripheral oxygen saturation (SpO2), heart rate, and blood pressure of children with cyanotic congenital heart disease who were undergoing dental extraction. METHODS: Forty-four patients between the ages of 6 and 12 years who underwent upper primary tooth extraction were included in the study. Of these, 20 patients were in the cyanotic congenital heart disease group and 24 were in the control group. RESULTS: Peripheral oxygen saturation, heart rate, and systolic blood pressure in the cyanotic congenital heart disease group varied quite significantly during the treatment protocol (p<0.05), with values of 80.5% (±7.6) to 82.8% (±7.8), 95.3 beats per minute (bpm) (±11.3) to 101.3 bpm (±9.8), and 93.6 mm Hg (±13,3) to 103.8 mm Hg (±12.7), respectively. The variations in the control group during the procedure were also significant. CONCLUSIONS: The changes observed during the study protocol, although statistically significant, were mild and lacked clinical relevance. The results indicate that dental treatment of children with cyanotic heart disease using a standardized protocol in decentralized offices without the support of a surgical center is safe.

Dutra, Rosane Menezes Faria; Neves, Itamara Lucia Itagiba; Neves, Ricardo Simoes; Atik, Edmar; de Paula Santos, Ubiratan

2014-01-01

426

Chick embryo heart rate during the last week of incubation: population studies.  

PubMed

1. A technique has been developed for the study of embryonic heart rate during the last week of incubation in a population of 84 embryos. 2. Heart rate is characteristic for a particular embryo but there are clear differences between individuals. 3. The population mean heart rate decreased from 262 beats/min at 14 d to a minimum of 250 beats/min at 19-5 d and then increased rapidly to more than 270 beats/min before hatching. 4. This pattern was repeatable and independent of the flock age. 5. Embryonic heart rate was also independent of egg size and hatching time. 6. The heart rate of male embryos was one to two beats/min lower than that of females. PMID:1276968

Laughlin, K F; Lundy, H; Tait, J A

1976-05-01

427

Reduction of heart rate by omega-3 fatty acids and the potential underlying mechanisms  

PubMed Central

An elevated resting heart rate is one of the strongest predictors of cardiovascular mortality and is independently associated with sudden cardiac death (SCD). Agents capable of reducing heart rate without significant side effects are therefore of particular interest for the prevention of SCD. Recent human and animal studies have shown that omega-3 fatty acids can reduce heart rate. Our work has shown that omega-3 fatty acids significantly reduce membrane electrical excitability of the cardiac myocyte by lowering its resting membrane potential and the duration of the refractory period through inhibition of ion channels. We propose that these actions may be the underlying mechanisms for the omega-3 fatty acid-induced reduction of heart rate observed in both humans and animals. The heart rate-lowering capability of omega-3 fatty acids may contribute to their preventive effect against SCD.

Kang, Jing X.

2012-01-01

428

Heart rate affects endothelial function in essential hypertension.  

PubMed

Increased heart rate (HR) is a risk factor for cardiovascular morbidity and mortality in the general population and in some clinical conditions. Endothelial dysfunction is an adverse prognostic factor for cardiovascular events. The aim of the study was to evaluate the effect of HR on central hemodynamic parameters and endothelial function in hypertension. We evaluated forearm blood flow (FBF) response to intra-arterial infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) in 30 patients with HR ?60 min(-1) and 30 with HR ?80 min(-1). The FBF was measured by strain-gauge plethysmography. Transesophageal atrial pacing was used to increase the HR. Radial artery applanation tonometry and pulse wave analysis were used to derive central aortic pressures and correlate hemodynamic indices. The FBF response to ACh is lower in hypertensives with HR ?60 min(-1) than in those with HR ?80 min(-1) (10.6 ± 4.2 vs. 13.6 ± 5.1 ml × 100 ml(-1) of tissue × min(-1), P < 0.001). Vascular resistance decreases to 9.3 ± 2.8 U in patients with lower HR versus 7.2 ± 2.1 U in those with higher HR (P = 0.002). The FBF response to SNP is similar in both groups. Central systolic and pulse pressure are higher in bradycardic patients than in those with HR ?80 min(-1) (140 ± 8 vs. 131 ± 8 mmHg, P = 0.0001 and 49 ± 10 vs. 39 ± 11 mmHg, P = 0.0001). All central hemodynamic parameters decrease during incremental atrial pacing. Augmentation index is the strongest predictor of endothelial dysfunction at multivariate analysis. These findings demonstrate that low HR affects endothelium-dependent vasodilation in hypertension. Increased central aortic pressure and hemodynamic correlates seem to be the underlying mechanisms by which bradycardia interferes with endothelium-dependent reactivity. PMID:21559746

Maio, Raffaele; Miceli, Sofia; Sciacqua, Angela; Leone, Giulia Galiano; Bruni, Rosamaria; Naccarato, Paola; Martino, Francesco; Sesti, Giorgio; Perticone, Francesco

2013-04-01

429

Reappraisal of heart rate variability in acute ischemic stroke.  

PubMed

Cardiac autonomic dysfunction is a common complication after acute ischemic stroke (IS). Prior investigators have emphasized that infarction of brain stem or hemispheres with insular involvement is related to this dysfunction and may predict poor clinical outcome. From the viewpoint of stroke physicians, however, all stroke patients, particularly large-artery atherosclerosis (LAA) should be monitored for possible cardiac complications after acute IS. This study aimed to investigate cardiac autonomic impaction in patients with acute IS and to make the comparison between LAA and small-vessel occlusion (SVO) subtypes. Of the 126 acute IS patients prospectively enrolled in this study, 32 had LAA, 56 had SVO, and 38 had undetermined etiology according to the Trial of Org 10172 in Acute Stroke Treatment criteria. Cardiac autonomic function of all patients was assessed by measuring heart rate variability (HRV). The low- and high-frequency components of HRV in all stroke patients were significantly lower than those of control subjects after comparing multivariable models, including additional adjustments for age, gender, and all risk factors. There were no significant differences on HRV between LAA and SVO although post hoc comparisons showed that stroke patients of SVO had increased sympathetic modulation and reduced vagal activity. In conclusion, in acute IS patients, both LAA and SVO are predisposed to have cardiac autonomic dysfunction, manifesting as abnormalities in HRV, whether in hemispheric or brain stem lesions. Stroke patients of SVO are at higher risks of cardiac abnormalities, which might suggest an early cardiac dysfunction because of long-term hypertension. The HF component of HRV thought to be for vagal control might be a cardinal marker for predicting cardiac autonomic dysfunction after acute IS. Short-term HRV spectral analysis is a convenient approach for stroke clinicians to assess autonomic function in acute stroke. Long-term follow-up for HRV and clinical outcome relative to LAA and SVO stroke subtypes is warranted, particularly when an abnormal HRV is found at admission. PMID:21601166

Chen, Chien-Fu; Lai, Chiou-Lian; Lin, Hsiu-Fen; Liou, Li-Min; Lin, Ruey-Tay

2011-06-01

430

Wavelet transform analysis of heart rate variability during myocardial ischaemia.  

PubMed

Analysis of heart rate variability (HRV) is a valuable, non-invasive method for quantifying autonomic cardiac control in humans. Frequency-domain analysis of HRV involving myocardial ischaemic episodes should take into account its non-stationary behaviour. The wavelet transform is an alternative tool for the analysis of non-stationary signals. Fourteen patients have been analysed, ranging from 40 to 64 years old and selected from the European Electrocardiographic ST-T Database (ESDB). These records contain 33 ST episodes, according to the notation of the ESDB, with durations of between 40s and 12 min. A method for analysing HRV signals using the wavelet transform was applied to obtain a time-scale representation for very low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands using the orthogonal multiresolution pyramidal algorithm. The design and implementation using fast algorithms included a specially adapted decomposition quadrature mirror filter bank for the frequency bands of interest. Comparing a normality zone against the ischaemic episode in the same record, increases in LF (0.0112 +/- 0.0101 against 0.0175 +/- 0.0208 s2 Hz(-1); p<0.1) and HF (0.0011 +/- 0.0008 against 0.00 17 +/- 0.0020 s2 Hz(-1); p<0.05) were obtained. The possibility of using these indexes to develop an ischaemic-episode classifier was also tested. Results suggest that wavelet analysis provides useful information for the assessment of dynamic changes and patterns of HRV during myocardial ischaemia. PMID:11954711

Gamero, L G; Vila, J; Palacios, F

2002-01-01

431

Foetal heart rate power spectrum response to uterine contraction.  

PubMed

Cardiotocography is the most diffused prenatal diagnostic technique in clinical routine. The simultaneous recording of foetal heart rate (FHR) and uterine contractions (UC) provides useful information about foetal well-being during pregnancy and labour. However, foetal electronic monitoring interpretation still lacks reproducibility and objectivity. New methods of interpretation and new parameters can further support physicians' decisions. Besides common time-domain analysis, study of the variability of FHR can potentially reveal autonomic nervous system activity of the foetus. In particular, it is clinically relevant to investigate foetal reactions to UC to diagnose foetal distress early. Uterine contraction being a strong stimulus for the foetus and its autonomic nervous system, it is worth exploring the FHR variability response. This study aims to analyse modifications of the power spectrum of FHR variability corresponding to UC. Cardiotocographic signal tracts corresponding to 127 UC relative to 30 healthy foetuses were analysed. Results mainly show a general, statistically significant (t test, p<0.01) power increase of the FHR variability in the LF 0.03-0.2 Hz and HF 0.2-1 in correspondence of the contraction with respect to a reference tract set before contraction onset. Time evolution of the power within these bands was computed by means of time-varying spectral estimation to concisely show the FHR response along a uterine contraction. A synchronised grand average of these responses was also computed to verify repeatability, using the contraction apex as time reference. Such modifications of the foetal HRV that follow a contraction can be a sign of ANS reaction and, therefore, additional, objective information about foetal reactivity during labour. PMID:16937160

Romano, M; Bifulco, P; Cesarelli, M; Sansone, M; Bracale, M

2006-03-01

432

Does the Aging Process Significantly Modify the Mean Heart Rate?  

PubMed Central

Background The Mean Heart Rate (MHR) tends to decrease with age. When adjusted for gender and diseases, the magnitude of this effect is unclear. Objective To analyze the MHR in a stratified sample of active and functionally independent individuals. Methods A total of 1,172 patients aged ? 40 years underwent Holter monitoring and were stratified by age group: 1 = 40-49, 2 = 50-59, 3 = 60-69, 4 = 70-79, 5 = ? 80 years. The MHR was evaluated according to age and gender, adjusted for Hypertension (SAH), dyslipidemia and non-insulin dependent diabetes mellitus (NIDDM). Several models of ANOVA, correlation and linear regression were employed. A two-tailed p value <0.05 was considered significant (95% CI). Results The MHR tended to decrease with the age range: 1 = 77.20 ± 7.10; 2 = 76.66 ± 7.07; 3 = 74.02 ± 7.46; 4 = 72.93 ± 7.35; 5 = 73.41 ± 7.98 (p < 0.001). Women showed a correlation with higher MHR (p <0.001). In the ANOVA and regression models, age and gender were predictors (p < 0.001). However, R2 and ETA2 < 0.10, as well as discrete standardized beta coefficients indicated reduced effect. Dyslipidemia, hypertension and DM did not influence the findings. Conclusion The MHR decreased with age. Women had higher values of MHR, regardless of the age group. Correlations between MHR and age or gender, albeit significant, showed the effect magnitude had little statistical relevance. The prevalence of SAH, dyslipidemia and diabetes mellitus did not influence the results.

Santos, Marcos Antonio Almeida; Sousa, Antonio Carlos Sobral; Reis, Francisco Prado; Santos, Thayna Ramos; Lima, Sonia Oliveira; Barreto-Filho, Jose Augusto

2013-01-01

433

Analysis of heart rate variability after a ranger training course.  

PubMed

We studied the effects of prolonged physical activities on resting heart rate variability (HRV) during a training session attended by 23 cadets of the French military academy. This course lasts 1 month and is concluded by a 5-day field exercise simulation with physical and psychological stress. Data collection took place before (B) and immediately at the end (E) of the course. It included HRV recordings during a stand test (5 minutes lying down and 5 minutes standing), with a Polar R-R monitor, followed by blood sampling to assay plasma testosterone. The results (B and E) showed that the testosterone level fell by approximately 28.6 +/- 7%, indicating a high level of fatigue. During the stand test, the total power (TP) of the HRV spectrum increased in a supine position. The TP of B was 5,515.7 ms2 (SE, 718.4) and of E was 13018.9 ms2 (SE, 2,539.2; p < 0.001). High-frequency (HF) normalized values increased and low-frequency (LF) normalized values fell, regardless of position (HF normalized values and LF normalized values: supine, p < 0.01, p < 0.05; standing, p < 0.05, p < 0.01, respectively). LF:HF ratio fell 66.2 (SE, 12.9%; p < 0.01) in a lying position. During the time-domain analysis of HRV, differences between adjacent normal R-R intervals more than 50 milliseconds, expressed as a percentage, and differences between the coupling intervals of adjacent normal RR intervals increased in the lying position (p < 0.001). These results as a whole suggest that parasympathetic nervous system activity increases with fatigue. PMID:15379067

Jouanin, Jean-Claude; Dussault, Caroline; Pérès, Michel; Satabin, Pascale; Piérard, Christophe; Guézennec, Charles Yannick

2004-08-01

434

Heart rate variability in normal and pathological sleep  

PubMed Central

Sleep is a physiological process involving different biological systems, from molecular to organ level; its integrity is essential for maintaining health and homeostasis in human beings. Although in the past sleep has been considered a state of quiet, experimental and clinical evidences suggest a noteworthy activation of different biological systems during sleep. A key role is played by the autonomic nervous system (ANS), whose modulation regulates cardiovascular functions during sleep onset and different sleep stages. Therefore, an interest on the evaluation of autonomic cardiovascular control in health and disease is growing by means of linear and non-linear heart rate variability (HRV) analyses. The application of classical tools for ANS analysis, such as HRV during physiological sleep, showed that the rapid eye movement (REM) stage is characterized by a likely sympathetic predominance associated with a vagal withdrawal, while the opposite trend is observed during non-REM sleep. More recently, the use of non-linear tools, such as entropy-derived indices, have provided new insight on the cardiac autonomic regulation, revealing for instance changes in the cardiovascular complexity during REM sleep, supporting the hypothesis of a reduced capability of the cardiovascular system to deal with stress challenges. Interestingly, different HRV tools have been applied to characterize autonomic cardiac control in different pathological conditions, from neurological sleep disorders to sleep disordered breathing (SDB). In summary, linear and non-linear analysis of HRV are reliable approaches to assess changes of autonomic cardiac modulation during sleep both in health and diseases. The use of these tools could provide important information of clinical and prognostic relevance.

Tobaldini, Eleonora; Nobili, Lino; Strada, Silvia; Casali, Karina R.; Braghiroli, Alberto; Montano, Nicola

2013-01-01

435

Conventional heart rate variability analysis of ambulatory electrocardiographic recordings fails to predict imminent ventricular fibrillation  

NASA Technical Reports Server (NTRS)

OBJECTIVES. The purpose of this report was to study heart rate variability in Holter recordings of patients who experienced ventricular fibrillation during the recording. BACKGROUND. Decreased heart rate variability is recognized as a long-term predictor of overall and arrhythmic death after myocardial infarction. It was therefore postulated that heart rate variability would be lowest when measured immediately before ventricular fibrillation. METHODS. Conventional indexes of heart rate variability were calculated from Holter recordings of 24 patients with structural heart disease who had ventricular fibrillation during monitoring. The control group consisted of 19 patients with coronary artery disease, of comparable age and left ventricular ejection fraction, who had nonsustained ventricular tachycardia but no ventricular fibrillation. RESULTS. Heart rate variability did not differ between the two groups, and no consistent trends in heart rate variability were observed before ventricular fibrillation occurred. CONCLUSIONS. Although conventional heart rate variability is an independent long-term predictor of adverse outcome after myocardial infarction, its clinical utility as a short-term predictor of life-threatening arrhythmias remains to be elucidated.

Vybiral, T.; Glaeser, D. H.; Goldberger, A. L.; Rigney, D. R.; Hess, K. R.; Mietus, J.; Skinner, J. E.; Francis, M.; Pratt, C. M.

1993-01-01

436

[Heart rate variability is significantly reduced in non-diabetic patients with hypertension].  

PubMed

Introductions: Heart rate variability is reduced among patients with hypertension or those with diabetes mellitus. Hypertension and diabetes show frequent co-morbidity, but it is still not entirely clear whether heart arte varia