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Abstract

Analysis of heart rate variation (HRV) has become a popular non-invasive 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 non-linear contributions. These signals are essentially non-stationary and may contain indicators of cardiac health. This work is an attempt made to do a quantitative study on the effect of reflexology on the heart rate variability (HRV) during reflexologic stimulation. The non-linear parameters are evaluated for this study and the results obtained for 20 subjects are tabulated.RésuméL'analyse de la variation de fréquence cardiaque (HRV) est devenue un outil non invasif très répandu pour évaluer les activités du système nerveux autonome. L'intérêt de la HRV réside dans le fait que les fluctuations rapides peuvent spécifiquement refléter des changements d'activité des systèmes sympathique et vagal. Elle prouve que la structure produisant du signal n'est pas simplement linéaire et met en jeu des fonctionnements non-linéaires. Les signaux sont essentiellement non stationnaires et peuvent refléter des dysfonctionnements cardiaques. Ce travail tente de faire une étude quantitative de l'effet des stimulations réflexologiques sur la variabilité de la HRV. Les paramètres non linéaires sont évalués dans cette étude et les résultats obtenus pour 20 sujets sont présentés.

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... Some studies have evaluated the effects of reflexology on heart rate variability. Joseph et al. 38 and Zhen et al. 39 found decreases in heart rate variability during reflexology in comparison to a relaxed sitting position. This result seems contra-intuitive and is contrary to findings from other types of massage techniques such as the myofascial trigger-point massage, which has been shown to increase heart rate variability. ...
... 28,37 Our results concerning heart rate variability are consistent with those of Delaney et al. 40 who also found increases in heart rate variability after myofascial trigger-point massage. However, our results are contrary to those of Joseph et al. 38 and Zhen et al. 39 who found decreases in heart rate variability during reflexology in comparison to a relaxed sitting position. This difference could be explained by the differential experimental procedures being used. ...
Article
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The present study evaluates the cardiovascu-lar effects of reflexology in a healthy sample. Forty-one participants were randomly assigned to one of three experimental groups: reflexolo-gy (n=15), non-professional foot massage (n=14), and a waiting time control group (n=12). Dependent variables were systolic, diastolic and mean blood pressure, inter-beat interval, heart rate variability and baroreceptor reflex sensitivity measured pre-and post-inter-ventions. The study was performed during three 40-min sessions separated by weekly intervals. Results show that the three manipu-lations produce similar increases in inter-beat interval, heart rate variability and baroreceptor reflex sensitivity. Reflexology specifically pro-duces an increase in blood pressure, which increases gradually over the three sessions. The parallel increase in heart rate variability and baroreceptor reflex sensitivity together with the increase in blood pressure suggest that reflexology is associated with a co-activa-tion of both sympathetic and parasympathetic branches of the Autonomic Nervous System. These changes could be helpful in optimizing homeostatic activity, promoting the healing process and increasing the human organism's capacity to respond adaptively to internal and external challenges. Finally, the observed phys-iological changes in the waiting-time control group shows the relevance of habituation processes and suggests the need for addition of waiting-time control groups in future studies.
... Another interesting physiological parameter of control, to analyse during the RF-EMF research, could be the electrocardiogram. The electrocardiogram channels should be included to detect not only spikes and sharp artefactual cardio-linked waves on the EEG -exactly like the electrooculogram-but also because it gives useful information about the autonomic nervous system control during the recording session (Acharya et al., 2002, Joseph et al., 2004, as reported by . Indeed, the heart rate variability analysis allows the measurement of the variation in intervals between heartbeats, which could be related to a stress condition linked to the experimental environment and protocol. ...
Thesis
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Avec l'utilisation sans cesse grandissante du téléphone portable, de plus en plus d'inquiétudes sont formulées concernant leurs effets potentiels sur la santé humaine, dont de possibles effets sur l'EEG de repos. Il n'y a pas à ce jour de réponses vraiment concluantes à ces questions. Nous avons réalisé pour la première fois dans ce domaine un protocole de magnétoencéphalographie et d'électroencéphalographie caractérisé par une très haute résolution temporelle et spatiale, afin de déterminer les régions corticales qui seraient impliquées dans ces effets. Des sujets sains jeunes adultes ont été exposés à des champs électromagnétiques à l'aide de deux téléphones issus du commerce, dont l'un a délivré une exposition "réelle" de radiofréquences à 900 MHz et l'autre une exposition factice ou "sham". Ces conditions d'exposition ont été définies par un ordre croisé, randomisé et contrebalancé en double-aveugle. L'analyse des données de magnétoencéphalographie enregistrées avant et après exposition a principalement montré une diminution de la densité de puissance spectrale des bandes alpha basse (8–10 Hz) et haute (10–12 Hz). Les régions corticales impliquées étaient dépendantes de la condition d'enregistrement "yeux ouverts" ou "yeux fermés". L'analyse des données EEG enregistrées en même temps que l'exposition n'a pas confirmé ces résultats sur la bande alpha (8–12 Hz) ni sur la bande de fréquence alpha individuelle. L'analyse de certains paramètres de contrôle, tels que le niveau de stress et la consommation de caféine, nous a permis d'exclure de potentiels biais sur nos résultats concernant les modulations des ondes alpha
... We have chosen HRV as an indirect measurement for the activity of the autonomic nervous system (ANS). 19 The ANS modulates the function of circulatory system; therefore, changes in HRV indicate changes in the ANS. 20 The use of HRV to measure the effects of MP radiation on the ANS is documented in scientific literature. ...
Article
Mobile phones (MPs) progressed from a tool of the privileged few to a gadget for the masses. However, the physical effects, which enable wireless information transmission, did not change; MP technology still relies on pulsed high-frequency electromagnetic (EM) fields. Therefore, the health risks, associated with EM fields, remain. Studies that investigated these health risks have reported dizziness, numbness in the thigh, and heaviness in the chest. This study investigates neurological effects that are caused by EM fields radiated from MPs. The heart rate variability (HRV) can be used as a measure for these neurological effects, because the automated nervous system modulates the HRV. We measured the HRV of 14 healthy male volunteers. We used the following nonlinear parameters to quantify the MP radiation effects on HRV: approximate entropy (ApEn), capacity dimension (CaD), correlation dimension (CD), fractal dimension (FD), Hurst exponent (H), and the largest Lyapunov exponent (LLE). The results indicate that there is a measurable difference in the parameter values when the MP is kept close to the chest and when it is kept close to the head. However, these differences are very small and statistical analysis showed that they have no clinical significance. Furthermore, the result analysis does not show a consistent trend, which indicates that there is no underlying pathological effect.
... Another interesting physiological parameter of control, to analyse during the RF-EMF research, could be the electrocardiogram. The electrocardiogram channels should be included to detect not only spikes and sharp artefactual cardio-linked waves on the EEG (Sinha et al., 2016)-exactly like the electrooculogram-but also because it gives useful information about the autonomic nervous system control during the recording session (Acharya et al., 2002;Joseph et al., 2004), as reported by (Ghosn et al., 2015). Indeed, the heart rate variability analysis allows the measurement of the variation in intervals between heartbeats, which could be related to a stress condition linked to the experimental environment and protocol. ...
... Another interesting physiological parameter of control, to analyse during the RF-EMF research, could be the electrocardiogram. The electrocardiogram channels should be included to detect not only spikes and sharp artefactual cardio-linked waves on the EEG (Sinha et al., 2016)-exactly like the electrooculogram-but also because it gives useful information about the autonomic nervous system control during the recording session (Acharya et al., 2002;Joseph et al., 2004), as reported by (Ghosn et al., 2015). Indeed, the heart rate variability analysis allows the measurement of the variation in intervals between heartbeats, which could be related to a stress condition linked to the experimental environment and protocol. ...
Article
In response to the exponential increase in mobile phone use and the resulting increase in exposure to radiofrequency electromagnetic fields (RF-EMF), there have been several studies to investigate via electroencephalography (EEG) whether RFEMF exposure affects brain activity. Data in the literature have shown that exposure to radiofrequency signals modifies the waking EEG with the main effect on the alpha band frequency (8–13 Hz). However, some studies have reported an increase in alpha band power, while others have shown a decrease, and other studies showed no effect on EEG power. Given that changes in the alpha amplitude are associated with attention and some cognitive aspects of human behavior, researchers deemed necessary to look whether alpha rhythm was modulated under RF-EMF exposure. The present review aims at comparing and discussing the main findings obtained so far regarding RF-EMF effects on alpha rhythm of human waking spontaneous EEG, focusing on differences in protocols between studies, which might explain the observed discrepancies and inconclusive results.
... Surprisingly, our search of the medical and scientific literature did not discover any reports on observed influences on the autonomic nervous system in general, and neither on the heart rate (and specifically its variability) during application of the reflex stimulation according to Vojta. At the same time, changes in HRV have been studied and reported for many other types of surface or other somatosensory stimulation, including nociceptive [18][19][20][21][22] . ...
Article
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Background: The physiotherapeutic technique of Vojta reflex locomotion is often accompanied by various autonomic activity changes and unpleasant sensations. It is unknown whether these effects are specific to Vojta Therapy. Therefore, the aim of this study was to compare changes in cardiac autonomic control after Vojta reflex locomotion stimulation and after an appropriate sham stimulation. Methods: A total of 28 young healthy adults (20.4 - 25.7 years) were enrolled in this single-blind randomized cross-over study. Participants underwent two modes of 20-minute sustained manual pressure stimulation on the surface of the foot on two separate visits. One mode used manual pressure on the lateral heel, i.e., in a zone employed in the Vojta Therapy (active stimulation). The other mode used pressure on the lateral ankle (control), in an area not included among the active zones used by Vojta Therapy and whose activation does not evoke manifestations of reflex locomotion. Autonomic nervous system activity was evaluated using spectral analysis of heart rate variability before and after the intervention. Results: The active stimulation was perceived as more unpleasant than the control stimulation. Heart rate variability parameters demonstrated almost identical autonomic responses after both stimulation types, showing either modest increase in parasympathetic activity, or increased heart rate variability with similar contribution of parasympathetic and sympathetic activity. Conclusion: The results demonstrate changes of cardiac autonomic control in both active and control stimulation, without evidence for a significant difference between the two.
... The HRV is a measure of the beat-to-beat variations (R–R interval). HRV is regarded as an activity indicator of autonomic regulation of circulatory function; notice that controversy exists over whether this is an accurate metric for analyzing cardiovascular autonomic control [10, 11]. A simple example of information extraction in time domain is the calculation of the standard deviation (STD) of beat-to-beat intervals [12] . ...
Article
This paper presents a contact-less system to detect the heartbeat activity from a distance of one meter. The proposed system is based on using a vector network analyzer. Measurements are performed at 16 GHz for different power levels between 0 and -25 dBm. Results for two S-parameters are obtained and compared to an ECG simultaneous signal in terms of heartbeat rate and heart rate variability.
... The HR is calculated as the average number of heartbeat per minute, while the HRV is a measure of the beat-to-beat variations (R-R interval). HRV is regarded as an activity indicator of autonomic regulation of circulatory function; noticing that a controversy exists over whether this is an accurate metric for analyzing cardiovascular autonomic control1112. A simple example of information extraction in time domain is the calculation of the standard deviation (STD) of beat-to-beat intervals [13]. ...
Conference Paper
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This paper presents a contact-less heartbeat detection system and a cardiopulmonary modeling. Using a vector network analyzer, our proposed microwave system shows the ability of detecting the heartbeat signal at different frequencies, as well as at different output power levels. Based on parameters extracted from real measurements, a model representing the heartbeat and the respiration signals is presented. Different processing techniques are used in order to separate the heartbeat and the respiration signals. For different signal to noise ratios, wavelet filters show higher accuracy over classic filters in determining both the heartbeat rate and the heart rate variability.
... The Heart Rate Variability is a measure of the beat-to-beat variations (R-R interval). HRV is regarded as an activity indicator of autonomic regulation of circulatory function; noting that controversy exists over whether this is an accurate metric for analyzing cardiovascular autonomic control [10,11]. A simple example of information extraction in time domain is the calculation of the standard deviation (STD) of beat-to-beat intervals [12]. ...
Conference Paper
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A new system for contact-less heartbeat detection is proposed. Operating at 2.4, 5.8, 10, 16, and 60 GHz, our system shows the possibility to detect the heartbeat rate at a distance of 1 m from the person. The heart rate variability is extracted as well. Originating from experimental measurements, a model presenting the cardiopulmonary activities is proposed. Separating the heartbeat signal from the respiration signal is done using different methods and for several SNR values.
... And corresponding non-linear parameters are noted for study and the results are discussed. That is ECG was taken during reflexology and Correlation dimension analysis was done.Hence they proved that reflexology is working [1].Jingguo Wangpropose a different application of 7-DOF redundant manipulator for doing massaging work on humanfeet through the tactile sensor furnished with end-effector. A real massage experiment is done on the human feet and the results establish the usefulness of the proposed control syste. ...
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To test the strength of Infrared (IR) thermography in spotting the blood circulation, on the foot with help of temperature changes, after guasatheraphy treatment. The treatment given, is referred as guasatheraphy in which pressure is applied using wooden stick.This paper proposes alternate medicine like reflexology as a medium which aids the patient to get rid of various diseases. Thermography is the technique used here to show the temperature changes that are produced while applying pressure under the foot. After applying particular strokes on the foot of the patient, the temperature changes are noted before and after guasatheraphy treatment .By using an infrared camera, the thermograms are captured. With the help of thesethermograms,changes in temperature are noted and hence the blood circulation is increased. A comparison graph for surface temperature was plotted between data’s which are obtained before and after treatment. The increase in foot temperature may be due to the proper circulation of blood. This proves that regions on the foot are linked with regions of the body, and thereby working on these one can recover his health issues. Hence thermography is used as a indicative as well as prognostic tool to prove the changes that occurs due to guasatheraphy.
... The HRV is a measure of the beat-to-beat variations (R-R interval). HRV is regarded as an activity indicator of autonomic regulation of circulatory function; notice that controversy exists over whether this is an accurate metric for analyzing cardiovascular autonomic control [10,11]. A simple example of information extraction in time domain is the calculation of the standard deviation (STD) of beat-to-beat intervals [12]. ...
Article
This work proposes a contactless multitunable microwave measurement scheme for heartbeat detection. Our system is based on simplicity and the ability of tuning two parameters: frequency and power. Measurements are performed at 2.4, 5.8, 10, 16, and 60 GHz. Operating at 2.4 GHz, the heartbeat signal is detected at different output power levels (from −2 down to −27 dBm). The heart rate variability is extracted for all the measurements. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 192–198, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24877
... The HRV is a measure of the beat-to-beat variations (R-R interval for the ECG signal). HRV is regarded as an activity indicator of autonomic regulation of circulatory function; notice that controversy exists over whether this is an accurate metric for analyzing cardiovascular autonomic control181920. The extraction of the heartbeat rate requires the use of simple averaging over a specific window. ...
Conference Paper
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This paper provides a validation approach for a microwave Doppler Radar system used for heartbeat detection. The proposed system is tested at 16 GHz with several transmitted power, simultaneously with a pc-based electrocardiogram. Obtained results show accurate detection for the heartbeat signal in terms of heartbeat rate and heart rate variability.
... The HRV is a measure of the beat-to-beat variations (R-R interval for the ECG signal). HRV is regarded as an activity indicator of autonomic regulation of circulatory function [18]. The extraction of the heartbeat rate requires the use of simple averaging over a specific window. ...
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This paper presents a single antenna Doppler system for contact-less heartbeat monitoring. The proposed system, based on using a vector network analyzer, is tested at 16 GHz frequency for different transmitted power levels between 0 and -25 dBm. Both heartbeat rate and heart rate variability are extracted from the signals obtained with the Doppler system and compared to simultaneous ECG signals.
Article
Abstract Objectives: Reflexology claims that the feet are representative of the body and that massage to specific points of the feet increases blood supply to "mapped" organs in the body. This review provides the first systematic evaluation of existing reflexology randomized controlled trials (RCTs) to determine whether there is any evidence to suggest the existence of a reflexology treatment-related hemodynamic effect; to examine whether reflexology researchers used study designs that systematically controlled for nonspecific effects in order to isolate this specific component; and to highlight some of the methodological challenges that need to be overcome to demonstrate specific and beneficial hemodynamic effects. Design: Fifty-two RCTs of reflexology published from 1990 to September 2011 were initially retrieved. Setting/Location: Cardiorespiratory Department, Highland Heartbeat Centre, Raigmore Hospital, Inverness. Subjects: Adult subjects. Interventions: Studies using reflexology foot massage techniques as the intervention versus sham reflexology treatment, simple foot massage, conventional treatment, or no treatment as the control were then selected. Outcome measures: Outcome measures included any hemodynamic parameter potentially involved in the regulation of circulating blood volume and flow, including heart rate and systolic and diastolic arterial blood pressure. Results: Seven RCTs suggested that reflexology has an effect on selected cardiovascular parameters; however, five of these delivered the reflexology intervention as a whole complex treatment, with the data collector often delivering the intervention themselves. Conclusions: This systematic review found that although reflexology has been shown to have an effect on selected hemodynamic variables, the lack of methodological control for nonspecific general massage effects means that there is little convincing evidence at this time to suggest the existence of a specific treatment-related hemodynamic effect. Furthermore, the review found that few studies of reflexology controlled for nonspecific effects in order to isolate any specific active component, despite the hemodynamic claim being a key part of the therapeutic value of reflexology. Therefore, further research approaches using more innovative designs and robust methods that can allow a treatment-induced, therapeutically beneficial hemodynamic effect to reveal itself are needed to help reflexology purchasers make a more informed decision about the safety and product quality of the reflexology hemodynamic claim and for reflexologists to be able to guarantee minimum product quality, validity, and safety standards in their practice.
Article
This article presents a contact‐less system to detect the heartbeat activity from a distance of 1 m. The proposed system is based on using a vector network analyzer. Measurements are performed at 16 GHz for different power levels between 0 and −25 dBm. Results for two S‐parameters are obtained and compared to an electrocardiogram simultaneous signal in terms of heartbeat rate and heart rate variability. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2610–2617, 2012; this online at wileyonlinelibrary.com. DOI 10.1002/mop.27152
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Analysis of heart rate variability (HRV) has become a popular non invasive tool for assessing the activities of autonomic nervous system. Depressed HRV has been found in several disorders, like diabetes mellitus (DM) and coronary artery disease, characterised by autonomic nervous dysfunction. A new technique, which searches for pattern repeatability in a time series, is proposed specifically for the analysis of heart rate data. These set of indices, which are termed as pattern repeatability measure and pattern repeatability ratio are compared with approximate entropy and sample entropy. In our analysis, based on the method developed, it is observed that heart rate variability is significantly different for DM patients (p=0.0272), particularly for patients with diabetic foot ulcer (p=0.0001).
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This book surveys recent developments in the analysis of physiological time series. The authors, physicists and mathematicans, physiologists and medical researchers, have succeeded in presenting a review of the new field of nonlinear data analysis as needed for more refined computer-aided diagnostics. Together with the techniques, they actually propose a new approach to the problems. The practitioners may find the many applications to the cardio-respiratory system, EEG analysis, motor control and voice signals very useful.
Article
Encopresis or faecal incontinence in children is an extremely distressing condition that is usually secondary to chronic constipation /stool withholding. Traditional management with enemas may add to the child’s distress. This study investigated the efficacy of treating patients with encopresis and chronic constipation with reflexology. An observational study was carried out of 50 children between three and 14 years of age who had a diagnosis of encopresis /chronic constipation. The children received six sessions of 30-minutes of reflexology to their feet. With the help of their parents they completed questionnaires on bowel motions and soiling patterns before, during and after the treatment. A further questionnaire was completed by parents pre and post treatment on their attitude towards reflexology. Forty-eight of the children completed the sessions. The number of bowel motions increased and the incidence of soiling decreased. Parents were keen to try the reflexology and were satisfied with the effect of reflexology on their child’s condition. It appears that reflexology has been an effective method of treating encopresis and constipation over a six-week period in this cohort of patients.
Article
This article describes an approach to chaotic modeling in which a continuous model is developed based on a conjectured solution to the logistic equation. As a result of this approach, two practical methods for quantifying variability in data sets have been derived. The first is a graphical representation obtained by using second-order difference plots of time series data. The second is a central tendency measure (CTM) that quantifies this degree of variability. The CTM can then be used as a parameter in decision models, such as neural networks. It appears that measuring the degree of variability is a more useful measure of chaos, as demonstrated by the application of this work to the analysis of congestive heart failure patients as compared to normal controls.
Article
Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.
Article
The objective of this pilot study is to identify if reflexology and foot massage (FM) affect the physiology of the body by measuring baroreceptor reflex sensitivity (BRS) using phase IV of the Valsalva manoeuvre, blood pressure (BP) and sinus arrhythmia (SA). The reflexology (n = 10) and FM groups (n = 10) showed significantly greater reductions in BRS compared to the control group (n = 4). Analysis of the mean differences between groups showed a greater difference in BRS between reflexology or FM and the control group than between reflexology and FM. This study found no significant difference in resting BP after intervention. The frequency of SA after reflexology and FM increased by 43.9% and 34.1% respectively. Further thoughts from the results of this study suggest a ‘neuro theory’ whereby reflexology and FM alter the BRS by stimulating the sensory nervous system in the feet.
Article
Proposes a new method based on phase space technique for the analysis of cardiovascular signals. The method is based on finding a measure which depends on the distribution of signals in phase space. Results obtained tend to support the feasibility of the proposed method in possibly detecting abnormal conditions in cardiovascular signals
Article
From the Publisher:Biomedical / Electrical Engineering Nonlinear Biomedical Signal Processing Volume II: Dynamic Analysis and Modeling A volume in the IEEE Press Series on Biomedical Engineering Metin Akay, Series Editor Featuring current contributions by experts in signal processing and biomedical engineering, this book introduces the concepts, recent advances, and implementations of nonlinear dynamic analysis methods. Together with Volume I in this series, this book provides comprehensive coverage of nonlinear signal and image processing techniques. Nonlinear Biomedical Signal Processing: Volume II combines analytical and biological expertise in the original mathematical simulation and modeling of physiological systems. Detailed discussions of the analysis of steady-state and dynamic systems, discrete-time system theory, and discrete modeling of continuous-time systems are provided. Biomedical examples include the analysis of the respiratory control system, the dynamics of cardiac muscle and the cardiorespiratory function, and neural firing patterns in auditory and vision systems. Examples include relevant MATLAB(r) and Pascal programs. Topics covered include:*Nonlinear dynamics*Behavior and estimation*Modeling of biomedical signals and systems*Heart rate variability measures, models, and signal assessments*Origin of chaos in cardiovascular and gastric myoelectrical activity*Measurement of spatio-temporal dynamics of human epileptic seizures.A valuable reference book for medical researchers, medical faculty, and advanced graduate students, it is also essential reading for practicing biomedical engineers. Nonlinear Biomedical Signal Processing, Volume II is anexcellent companion to Dr. Akay's Nonlinear Biomedical Signal Processing, Volume I: Fuzzy Logic, Neural Networks, and New Algorithms.
Article
Suppose that a dynamical system has a chaotic attractor A with a correlation dimension D2. A common technique to probe the system is by measuring a single scalar function of the system state and reconstructing the dynamics in an m-dimensional space using the delay-coordinate technique. The estimated correlation dimension of the reconstructed attractor typically increases with m and reaches a plateau (on which the dimension estimate is relatively constant) for a range of large enough m values. The plateaued dimension value is then assumed to be an estimate of D2 for the attractor in the original full phase space. In this paper we first present rigorous results which state that, for a long enough data string with low enough noise, the plateau onset occurs at m = Ceil(D2), where Ceil(D2), standing for ceiling of D2, is the smallest integer greater than or equal to D2. We then numerical examples illustrating the theoretical prediction. In addition, we discuss new findings showing how practical factors such as a lack of data and observational noise can produce results that may seem to be inconsistent with the theoretically predicted plateau onset at m = Ceil(D2).
Article
The electrocardiogram is a representative signal containing information about the condition of the heart. The shape and size of the P-QRS-T wave, the time intervals between its various peaks, etc. may contain useful information about the nature of disease afflicting the heart. However, these subtle details cannot be directly monitored by the human observer. Besides, since bio-signals are highly subjective, the symptoms may appear at random in the time scale. Therefore, the signal parameters, extracted and analysed using computers, are highly useful in diagnostics. This paper deals with the classification of certain diseases using artificial neural network (ANN) and fuzzy equivalence relations. The heart rate variability is used as the base signal from which certain parameters are extracted and presented to the ANN for classification. The same data is also used for fuzzy equivalence classifier. The feedforward architecture ANN classifier is seen to be correct in about 85% of the test cases, and the fuzzy classifier yields correct classification in over 90% of the cases.
Chapter
The time variability of many natural and social phenomena is not well described by standard methods of data analysis. However, nonlinear time series analysis uses chaos theory and nonlinear dynamics to understand seemingly unpredictable behavior. The results are applied to real data from physics, biology, medicine, and engineering in this volume. Researchers from all experimental disciplines, including physics, the life sciences, and the economy, will find the work helpful in the analysis of real world systems. First Edition Hb (1997): 0-521-55144-7 First Edition Pb (1997): 0-521-65387-8
Chapter
Preface; Acknowledgements; Part I. Basic Topics: 1. Introduction: why nonlinear methods?; 2. Linear tools and general considerations; 3. Phase space methods; 4. Determinism and predictability; 5. Instability: Lyapunov exponents; 6. Self-similarity: dimensions; 7. Using nonlinear methods when determinism is weak; 8. Selected nonlinear phenomena; Part II. Advanced Topics: 9. Advanced embedding methods; 10. Chaotic data and noise; 11. More about invariant quantities; 12. Modelling and forecasting; 13. Non-stationary signals; 14. Coupling and synchronisation of nonlinear systems; 15. Chaos control; Appendix A: using the TISEAN programs; Appendix B: description of the experimental data sets; References; Index.
Article
We study the correlation exponent v introduced recently as a characteristic measure of strange attractors which allows one to distinguish between deterministic chaos and random noise. The exponent v is closely related to the fractal dimension and the information dimension, but its computation is considerably easier. Its usefulness in characterizing experimental data which stem from very high dimensional systems is stressed. Algorithms for extracting v from the time series of a single variable are proposed. The relations between the various measures of strange attractors and between them and the Lyapunov exponents are discussed. It is shown that the conjecture of Kaplan and Yorke for the dimension gives an upper bound for v. Various examples of finite and infinite dimensional systems are treated, both numerically and analytically.
Article
The heart and vasculature have been viewed for too long as a self contained system. Arrhythmias have been treated by suppression of one or another property of myocardial excitability, but extracardiac factors also have a role in the genesis of sporadic, paroxysmal ventricular arrhythmias as well as ventricular fibrillation. In animal models, manipulation of the sympathetic neural input affects cardiac vulnerability; in the ischemic myocardium, such manipulation may be a sufficient stimulus to induce fibrillation. Psychologic stresses, even of brief duration, profoundly reduce the threshold for ventricular fibrillation and result in major ventricular rhythm disorders. In man, the occurrence of ventricular arrhythmias is likewise correlated with the activity of the sympathetic nervous system. Especially relevant are three recent studies suggesting that in patients who have recovered from acute myocardial infarction, the incidence of sudden death is markedly reduced by beta adrenergic blocking drugs. It may be that pharmacologic treatments for prevention of sudden death should be focused on restraining neurophysiologic triggers rather than protecting the cardiac target.
Article
Diminished heart rate variability is associated with high sympathetic tone and an increased mortality rate in heart failure cases. We constructed Poincaré plots of each sinus R-R interval plotted against the subsequent R-R interval from 24-hour Holter recordings of 24 healthy subjects (control group) and 24 patients with heart failure. Every subject in the control group had a comet-shaped Poincaré plot resulting from an increase in beat-to-beat dispersion as heart rate slowed. No patient with heart failure had this comet-shaped pattern. Instead, three distinctive patterns were identified: (1) a torpedo-shaped pattern resulting from low R-R interval dispersion over the entire range of heart rates, (2) a fanshaped pattern resulting from restriction of overall R-R interval ranges with enhanced dispersion, and (3) complex patterns with clusters of points characteristic of stepwise changes in R-R intervals. Poincaré pattern could not be predicted from standard deviations of R-R intervals. This first use of Poincaré plots in heart rate variability analysis reveals a complexity not readily perceived from standard deviation information. Further study is warranted to determine if this method will allow refined assessment of cardiac-autonomic integrity in heart failure, which could help identify patients at highest risk for sudden death.
Article
Reduced heart rate variability carries an adverse prognosis in patients who have survived an acute myocardial infarction. This article reviews the physiology, technical problems of assessment, and clinical relevance of heart rate variability. The sympathovagal influence and the clinical assessment of heart rate variability are discussed. Methods measuring heart rate variability are classified into four groups, and the advantages and disadvantages of each group are described. Concentration is on risk stratification of postmyocardial infarction patients. The evidence suggests that heart rate variability is the single most important predictor of those patients who are at high risk of sudden death or serious ventricular arrhythmias.
Article
Follow-up studies of psychiatric patients with panic disorder have shown an abnormally high mortality rate in men due to cardiovascular and cerebrovascular events. The authors report that in the New Haven portion of the Epidemiologic Catchment Area program the risk for stroke in persons with lifetime diagnoses of panic disorder was over twice that in persons with other psychiatric disorders or no psychiatric disorder. After adjustments for demographic differences between groups, the risk was even higher. While the results should be interpreted cautiously because of the small sample and absence of medical examinations, these findings are consistent with clinical studies showing an association between panic disorder and cardiovascular/cerebrovascular events.
Article
Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.
Article
Beat-to-beat heart rate (HR) dynamics were studied by plotting each R-R interval as a function of the previous R-R interval (Poincaré plot) during incremental doses of atropine followed by exercise for 10 subjects and during exercise without autonomic blockade for 31 subjects. A quantitative two-dimensional vector analysis of a Poincaré plot was used by measuring separately the standard deviation of instantaneous beat-to-beat R-R interval variability (SD1) and the standard deviation of continuous long-term R-R interval variability (SD2) as well as the SD1/SD2 ratio. Quantitative Poincaré measures were compared with linear measures of HR variability (HRV) and with approximate entropy (ApEn) at rest and during exercise. A linear progressive reduction was observed in SD1 during atropine administration, and it remained almost at the zero level during exercise after a parasympathetic blockade. Atropine resulted in more variable changes in SD2 and the SD1/SD2 ratio, but during exercise after parasympathetic blockade, a progressive increase was observed in the SD1/SD2 ratio until the end of exercise. The SD1/SD2 ratio had no significant correlations with the frequency domain measures of HRV. However, the SD1/SD2 ratio had a modest correlation with ApEn at rest (r = -0.69, P < 0.001), but not during exercise (r = 0.27, P = NS). All measures of vagal modulation of HR decreased progressively until the ventilatory threshold level was reached, when sympathetic activation was reflected as changes in the SD1/SD2 ratio. These results show that quantitative two-dimensional vector analysis of a Poincaré plot can provide useful information on vagal modulation of R-R interval dynamics during exercise that are not easily detected by linear summary measures of HRV or by ApEn.
Article
1. Time domain summary statistics and frequency domain parameters can be used to measure heart rate variability. More recently, qualitative methods including the Poincaré plot have been used to evaluate heart rate variability. The aim of this study was to validate a novel method of quantitative analysis of the Poincaré plot using conventional statistical techniques. 2. Beat-to-beat heart rate variability was measured over a relatively short period of time (10–20 min) in 12 healthy subjects aged between 20 and 40 years (mean 30 ± 7 years) during (i) supine rest, (ii) head-up tilt (sympathetic activation, parasympathetic nervous system activity withdrawal), (iii) intravenous infusion of atropine (parasympathetic nervous system activity withdrawal), and (iv) after overnight administration of low-dose transdermal scopolamine (parasympathetic nervous system augmentation). 3. The ‘width’ of the Poincaré plot, as quantified by SD delta R—R (the difference between successive R—R intervals), was determined at rest (median 48.9, quartile range 20 ms) and found to be significantly reduced during tilt (median 19.1, quartile range 13.7 ms, P < 0.01) and atropine administration (median 7.1, quartile range 5.7 ms, P < 0.01) and increased by scopolamine (median 79.3, quartile range 33 ms, P < 0.01). Furthermore, log variance of delta R—R intervals correlated almost perfectly with log high-frequency (0.15–0.4 Hz) power (r = 0.99, P < 0.01). 4. These findings strongly suggest that the ‘width’ of the Poincaré plot is a measure of parasympathetic nervous system activity. The Poincaré plot is therefore a quantitative visual tool which can be applied to the analysis of R—R interval data gathered over relatively short time periods.
Article
Heart rate variability is a recognized tool for the estimation of cardiac autonomic modulations. Recently, several studies have advanced the field of heart rate variability in three areas: 1) in technical modes of electrocardiogram processing and heart rate variability assessment, 2) in physiologic understanding and interpretation, and 3) in clinical and practical use. The most recent technical studies concentrate on the analysis of nonlinear aspects of heart period variations and on coherence between electrocardiogram variability and other physiologic factors such as respiration. Principal physiologic investigations studied the components of heart rate variability attributable to the individual limbs of the autonomic nervous system. It is becoming recognized that behavior and responses to the environment, including the psychosocial environment, play an important role in long-term heart rate variability. Established clinical applications of heart rate variability are presently restricted to the assessment of risk after myocardial infarction and to the early diagnosis of diabetic neuropathy. Nevertheless, recent studies indicate that heart rate variability might soon become a similarly powerful tool for risk prediction and monitoring of disease progression in congestive heart failure and for monitoring or reinnervation after heart transplantation.
Article
The mutual information I is examined for a model dynamical system and for chaotic data from an experiment on the Belousov-Zhabotinskii reaction. An N logN algorithm for calculating I is presented. As proposed by Shaw, a minimum in I is found to be a good criterion for the choice of time delay in phase-portrait reconstruction from time-series data. This criterion is shown to be far superior to choosing a zero of the autocorrelation function.
Article
Heart rate variability (HRV) is concerned with the analysis of the intervals between heartbeats. An emerging analysis technique is the Poincaré plot, which takes a sequence of intervals and plots each interval against the following interval. The geometry of this plot has been shown to distinguish between healthy and unhealthy subjects in clinical settings. The Poincaré plot is a valuable HRV analysis technique due to its ability to display nonlinear aspects of the interval sequence. The problem is, how do we quantitatively characterize the plot to capture useful summary descriptors that are independent of existing HRV measures? Researchers have investigated a number of techniques: converting the two-dimensional plot into various one-dimensional views; the fitting of an ellipse to the plot shape; and measuring the correlation coefficient of the plot. We investigate each of these methods in detail and show that they are all measuring linear aspects of the intervals which existing HRV indexes already specify. The fact that these methods appear insensitive to the nonlinear characteristics of the intervals is an important finding because the Poincaré plot is primarily a nonlinear technique. Therefore, further work is needed to determine if better methods of characterizing Poincaré plot geometry can be found.
Article
Because of the widely presumed association between heart disease and psychological wellbeing, the use of so-called 'complementary' therapies as adjuncts to conventional treatment modalities have been the subject of considerable debate. The present study arose from an attempt to identify a safe and effective therapeutic intervention to promote wellbe ing, which could be practicably delivered by nurses to patients in the postoperative recovery period following coronary artery bypass graft (CABG) surgery. Aim. To investigate the impact of foot massage and guided relaxation on the wellbeing of patients who had undergone CABG surgery. Twenty-five subjects were randomly assigned to either a control or one of two intervention groups. Psychological and physical variables were measured immediately before and after the intervention. A discharge questionnaire was also administered. No significant differences between physiological parameters were found. There was a significant effect of the intervention on the calm scores (ANOVA, P=0.014). Dunnett's multiple comparison showed that this was attributable to increased calm among the massage group. Although not significant the guided relaxation group also reported substantially higher levels of calm than control. There was a clear (nonsignificant) trend across all psychological variables for both foot massage and, to a lesser extent, guided relaxation to improve psychological wellbeing. Both interventions were well received by the subjects. These interventions appear to be effective, noninvasive techniques for promoting psychological wellbeing in this patient group. Further investigation is indicated.
Article
Encopresis or faecal incontinence in children is an extremely distressing condition that is usually secondary to chronic constipation/stool withholding. Traditional management with enemas may add to the child's distress. This study investigated the efficacy of treating patients with encopresis and chronic constipation with reflexology. An observational study was carried out of 50 children between three and 14 years of age who had a diagnosis of encopresis/chronic constipation. The children received six sessions of 30-minutes of reflexology to their feet. With the help of their parents they completed questionnaires on bowel motions and soiling patterns before, during and after the treatment. A further questionnaire was completed by parents pre and post treatment on their attitude towards reflexology. Forty-eight of the children completed the sessions. The number of bowel motions increased and the incidence of soiling decreased. Parents were keen to try the reflexology and were satisfied with the effect of reflexology on their child's condition. It appears that reflexology has been an effective method of treating encopresis and constipation over a six-week period in this cohort of patients.
Article
In the last decade, chaos theory has become a popular method for approaching the analysis of nonlinear data for which most mathematical models produce intractable solutions. The concept of chaos was first introduced with applications in meteorology. Since then, considerable work has been done in the theoretical aspects of chaos. Applications have abounded, especially in medicine and biology. A particularly active area for the application of chaos theory has been cardiology. Many aspects of heart disease have been addressed, including whether chaos represents the healthy or diseased state. Most approaches to chaotic modeling rely on discrete models of continuous problems, which are represented by computer algorithms. Due to the nature of chaotic models, both the discretization and the computer simulation can lead to propagation of errors that may overtake the actual solution. This article describes an approach to chaotic modeling in which a continuous model is developed based on a conjectured solution to the logistic equation. As a result of this approach, two practical methods for quantifying variability in data sets have been derived. The first is a graphical representation obtained by using second-order difference plots of time series data. The second is a central tendency measure (CTM) that quantifies this degree of variability. The CTM can then be used as a parameter in decision models, such as neural networks. It appears that measuring the degree of variability is a more useful measure of chaos, as demonstrated by the application of this work to the analysis of congestive heart failure patients as compared to normal controls
Article
We present a simple efficient algorithm for the derivation of a heart rate signal from the electrocardiogram. We demonstrate that the amplitude spectrum of this heart rate signal more closely matches that of the input signal to an integral pulse frequency modulation (IPFM) model of the heart's pacemaker than do the spectra of other ECG-derived heart rate signals. The applicability of this algorithm in cross-spectral analysis between heart rate and other physiologic signals is also discussed.
Article
We have developed a real-time algorithm for detection of the QRS complexes of ECG signals. It reliably recognizes QRS complexes based upon digital analyses of slope, amplitude, and width. A special digital bandpass filter reduces false detections caused by the various types of interference present in ECG signals. This filtering permits use of low thresholds, thereby increasing detection sensitivity. The algorithm automatically adjusts thresholds and parameters periodically to adapt to such ECG changes as QRS morphology and heart rate. For the standard 24 h MIT/BIH arrhythmia database, this algorithm correctly detects 99.3 percent of the QRS complexes.
Article
It is found that a heartbeat period fluctuation usually has a power spectral density which is inversely proportional to frequency, to which a spike is added at a breathing frequency.
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