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Objective:To research a fast-implementation method of correlation dimension of ECG signal base on LabVIEW.Methods: In this paper, acquisition ,display and processing of ECG signal were implemented through applied PCI-6023E as hardware and applied graphical programming language LabVIEW as development software. And then through software programming to realize fast calculation for correlation dimension of ECG signal.Results: This method was used to analyze and calculate the correlation dimension of ECG between patients with coronary heart disease and healthy people. And the experiment indicated that it can fast and reliably calculate the correlation dimension, and the correlation dimension of patients with coronary heart disease was obviously lower than that of healthy people.Conclusion: The correlation dimension system of ECG signal based on LabVIEW can realize the fast calculation of correlation dimension of ECG signal, and solve the two problems that heart rate variability (HRV) information are difficultly extracted from ECG signal and the extracted useful information are inadequate. Therefore, it provides important reference information for clinical diagnosis and treatment.
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ObjectiveTo study the changes of cardiac autonomic nervous function and EEG non-linear dynamics character in depressive patients,and to explore the functional activity state of brain.Methods24-hour ambulatory ECG was recorded in 47 depressive patients and 47 normal control people by multi-channel ECG machine.The index of heart rate variability,the incidence of arrhythmias and the relationship between HRV and the severity of depression were analyzed.ResultsCompared with the control group,the standard deviation of NN intervals(SDNN)((91.31±15.11)ms),the standard deviation of normal number of intervals(SDANN)((82.14±16.26)ms),the root mean square of successive differences (RMSSD)((37.13±8.02)ms),the percentage of pairs of adjacent RR intervals differing by >50 ms (PNN50)(11.05±7.02) and High-frequency(HF)((17.07±4.34)ms) in depression group were lower,however low-frequency(LF)((18.27±6.32)ms) and LF/HF((1.07±0.33)ms) were higher(P<0.05).There were positive linear correlation between depression severity and LF/HF(P <0.05,r=0.332) and negative linear correlation between depression severity and SDNN(P<0.05,r=-0.296).Compared with control group,the incidence rate of arrhythmia of depressive group was increased,especially in supraventricular arrhythmias.In quiet state with eyes closed: compared with the control group,the level of correlation dimension (D2) in left occiput,left middle and behind temple region were increased in group A,but the difference was not statistically significant.In group B,except prefrontal area,the D2 of the left hemisphere were increased especially in the left central area(3.91±0.37),left parietal lobe(3.85±0.43),left occipital(4.10±0.54)and left temporal(4.20±0.61) compared with control group (P<0.01).The brain electrical activity in other areas were not found change.ConclusionThe cardiac autonomic nervous function of depressive patient is positively correlated with the the severity of depression.Depressive patients are likely to conduct supraventricular arraythmia.Left hemisphere cerebral cortex is active in depressive patients by analysing the EEG non-linear dynamics character.
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Objective: To compare the correlation dimension (CD) of heart rate variability (HRV) in adults with and without abnormal electrocardiogram (ECG). Methods: A 24-hr Holter and a standard ECG were recorded from 100 university workers. After exclusion of 10 recordings with more than 5% of false RR intervals, a total of 90 subjects (age 46.2±8.7 years old, 45 were women) were included in the study. Two cardiologists classified 29 standard ECG as abnormal. CD was calculated from HRV time-series of 10,000 beats in the morning (from 11am), afternoon (from 5pm) and night (from 2am). Demographical characteristics were compared by ANOVA (considering ECG diagnosis and sex as independent factors) or by Fisher's exact test. Mean CD values were compared by analysis of variance considering as independent factors the ECG diagnosis, sex and time of day. Results: All demographical characteristics were similar except for a higher proportion of males with abnormal ECG (69%) than with normal ECG (41%). CD was not different with respect to the time of day, but it was higher in subjects with normal ECG (10.86 ± 2.41) than those with abnormal ECG (10.20 ± 2.48), and it was also higher in females than males: 11.04 ± 2.14 versus 10.63 ± 2.71 (normal ECG group), 10.84 ± 2.41 versus 9.92 ± 2.44 (abnormal ECG group). Conclusion: The finding of abnormal ECG is associated with HRV decreased complexity in adults.
Objetivo: Comparar la dimensión de correlación (DC) de la variabilidad de la frecuencia cardiaca (VFC) entre adultos con electrocardiograma (ECG) normal y anormal. Métodos: Se registró un Holter de 24 horas y un electrocardiograma (ECG) estándar de 100 trabajadores universitarios. Después de la exclusión de 10 registros con más de 5% de intervalos RR falsos, se incluyeron en el estudio a 90 sujetos (edad 46.2±8.7 años, 45 mujeres). Dos cardiólogos clasificaron 29 ECG estándar como anormales. La DC se calculó en series de tiempo de VFC de 10,000 latidos en la mañana (desde las 11:00), tarde (desde las 17:00) y noche (desde las 2:00). Las características demográficas fueron comparadas mediante análisis de varianza (considerando diagnóstico de ECG y sexo como factores independientes) o con prueba exacta de Fisher. Los valores promedio de DC fueron comparados con análisis de varianza considerando como factores independientes el diagnóstico de ECG, sexo y hora del día. Resultados: Las características demográficas fueron similares excepto por mayor proporción de hombres con ECG anormal (69%) que normal (41%). La DC no fue diferente con respecto a la hora del día, pero fue mayor en sujetos con ECG normal (10.86 ± 2.41) que con ECG anormal (10.20 ± 2.48), y también fue mayor en mujeres que en hombres: 11.04 ± 2.14 vs 10.63 ± 2.71 (grupo de ECG normal), 10.84 ± 2.41 vs 9.92 ± 2.44 (grupo de ECG anormal). Conclusión: El hallazgo de ECG anormal en adultos está asociado con menor complejidad de la VFC.
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Evaluar el comportamiento de la frecuencia cardíaca fetal a través del análisis no lineal en fetos sanos y con restricción del crecimiento intrauterino. Unidad de Perinatología, Departamento Clínico Integral de la Costa, Escuela de Medicina y Departamento de Matemáticas, Facultad de Ciencias y Tecnología, Universidad de Carabobo. Se trata de una investigación observacional, analítica, de corte transversal; se analizaron 60 registros de la frecuencia cardíaca fetal de 40 fetos sanos y de 20 fetos con restricción del crecimiento intrauterino entre las 30 y 42 semanas de gestación. Cada registro de la frecuencia cardíaca fetal en papel se convirtió a formato digital; se estableció la complejidad de cada registro de la frecuencia cardíaca fetal obtenida a través de los métodos de la asimetría del tiempo de reverso y el máximo exponente de Lyapunov. Se utilizó la dimensión de correlación (D2) para cuantificar el comportamiento caótico. Se determinó la complejidad de los registros de la frecuencia cardíaca fetal obtenidos; la dimensión de correlación de los fetos con restricción del crecimiento intrauterino (0,90 ± 0,03) fue menor que la calculada en los fetos sanos (0,93 ± 0,02), probándose su significancia estadística (P = 0,012). La correlación de dimensión disminuidas en fetos con restricción del crecimiento nos indica que la regulación de su dinámica cardíaca es menos compleja, probablemente está limitada la integridad del control del sistema cardiovascular y por ende su capacidad de adaptación frente a noxas externas o internas, estableciendo que el análisis no lineal permite diferenciar los fetos sanos de los fetos con restricción del crecimiento intrauterino.
To evaluate the behavior of the fetal frequency cardiac through nonlinear analysis in healthy fetuses and with intrauterine growth restriction. Unidad de Perinatología, Departamento Clínico Integral de la Costa, Escuela de Medicina y Departamento de Matemáticas, Facultad de Ciencias y Tecnología, Universidad de Carabobo. This work is an observational, analytical investigation, of cross-section; 60 registries of the fetal heart rate of 40 normal fetuses and 20 intrauterine growth restricted fetuses between 30 and 42 gestation weeks were analyzed. Each registry in paper of the fetal heart rate became to digital format; in the search of the possible complex behavior of each monitoring records was applied the asymmetry of the reverse time and the maximum exponent of Lyapunov. The chaotic behavior of each one of them by means of the dimension of correlations was quantified (D2). Was given the complexity of the fetal heart rate records; the correlation dimension of intrauterine growth restricted fetuses (0.90 ± 0.03), was lower than of the normal fetuses (0.93 ± 0.02) proving its statistical significance (P = 0.002). The correlation dimension diminished in intrauterine growth restricted fetuses indicates that the regulation of its cardiac dynamics is less complex, probably is limited the integrity of the cardiovascular control and therefore its capacity of adaptation to external or internal noxas, establishing that the nonlinear analysis allows differentiating the healthy fetuses from intrauterine growth restricted fetuses.
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Humans , Female , Pregnancy , Fetal Development , Nonlinear Dynamics , Heart Rate, Fetal , Fetal Growth RetardationABSTRACT
Objective: To introduce the advantages of approximate entropy (ApEn) in analyzing biological signals, to discuss the influences of time series' parameters on ApEn and elaborate the present conditions and prospects of its application on medicine. Methods: According to the definition and algorithm, ApEn has advantages on estimating the complexity of signal comparing with other non-linear analysis methods such as correlation dimension, fractal dimension, lyapunov index etc. Based on ApEn algorithm, we formulate programme to quantificationlly analyze the relationship between ApEn and each parameter of time series; Human EEG and ECG and other biological signals can reflect the state of the body. Through detecting changes of biological signals'ApEn, we can detect and monitor the state of an organization. Results: ApEn has many advantages such as a good anti-noise ability, the short date and so on. It makes up the defects of the correlation dimension ect. ApEn has nothing with the amplitude of time series. In the range of low-frequency, ApEn almost increases with frequency. When the date length is more than 1000 points, ApEn is stable. It quantificationlly describes that ApEn only requires short date. Recently. ApEn is widely used in diagnostics, monitoring, anesthesiology, and achieves good results. Conclusion: ApEn is a new developed non-linear analysis method which can estimate the complexity of the signal quantificationlly. It provides a new approach for diagnosing and monitoring a number of diseases. It has a wide application prospect.
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OBJECTIVE: The recent nonlinear analyses of electroencephalogram (EEG) data have shown that the correlation dimension (D2) reflects the degree of integration of information processing in the brain. There is now considerable evidence that auditory hallucination (AH) reflects dysfunctional gamma and beta frequency oscillations. Gamma oscillations are thought to reflect internally driven representations of objects, and the occurrence of subsequent beta oscillations can reflect the modification of the neuronal circuitry used to encode the sensory perception. The purpose of this study was to test whether AH in schizophrenia patients is reflected in abnormalities in D2 in their EEG, especially in the gamma and beta frequency bands. METHODS: Twenty-five schizophrenia patients with a history of treatment-refractory AH over at least the past 2 years, and 23 schizophrenia patients with no AH (N-AH) within the past 2 years were recruited for the study. Artifact-free 30-s EEG epochs during rest were examined for D2. RESULTS: The AH patients showed significantly increased gamma frequency D2 in Fp2 and decreased beta frequency D2 in the P3 region compared with the N-AH patients. These results imply that gamma frequency D2 in the right prefrontal cortex is more chaotic and that beta frequency D2 in the left parietal cortex is more coherent (less chaotic) in AH patients than in N-AH patients. CONCLUSION: Our study supports the previous evidence indicating that gamma and beta oscillations are pivotal to AH, and also shows the distinctive dimensional complexity between the right prefrontal and left parietal cortexes as the underlying biological correlates of AH in schizophrenia patients.
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Humans , Electronic Data Processing , Brain , Electroencephalography , Hallucinations , Neurons , Prefrontal Cortex , Rabeprazole , SchizophreniaABSTRACT
@#Objective To investigate the changes of non-linear dynamics characteristics of electroencephalogram(EEG) in patients with the stagnation of Liver-Qi syndrome.Methods 15 Liver-Qi stagnation syndrome patients and 15 normal persons were paired by sex and age.The data of EEG under three states(eyes closed,eyes opened,and mental arithmetic with eyes opened) were analyzed by the parameter of point-wise correlation dimension(PD2).Results PD2 of the stagnation of Liver-Qi syndrome group increased significantly compared with that of the healthy control group and always maintain high level.The difference of PD2 between two groups was gradually reduced along with the increase of stimulated condition.Conclusion Non-linear dynamic analysis is more appropriate for the study of mental functions changes of stagnation of Liver-Qi syndrome and can be used to investigate the brain mechanism of the stagnation of Liver-Qi syndrome.
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OBJECTIVE: This study was done to propose a new method of determining the cutoff frequency against measurement noise in fetal heart rate signal and to analyze the discriminating value for normal fetus (pH>7.15) and abnormal fetus (pH< or =7.15) by nonlinear method. METHODS: The patients were classified by umbilical artery pH (7.15) or base excess (-10 mEq/L). After removing the high frequency noise components at the cutoff frequency determined in this study, we calculated correlation dimension as a discriminating value for the normal and abnormal fetuses. RESULTS: After low pass filtering of fetal heart rate signal at the cutoff frequency, the numerical result of embedding dimension was 5.47+/-0.67 (normal), 4.43+/-0.60 (abnormal) (p<0.001), and correlation dimension was 2.51+/-0.43 (normal), 1.79+/-0.15 (abnormal). CONCLUSION: We could determine the cutoff frequency from the different fluctuation level between high frequency noise and principal signal according the cutoff frequency function. The detection of fetal distress was done objectively by this method. We could discriminate between normal fetus and abnormal fetus by correlation dimension as indicator for the nonlinear complexity.
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Female , Humans , Pregnancy , Fetal Distress , Fetal Heart , Fetus , Heart Rate, Fetal , Hydrogen-Ion Concentration , Noise , Umbilical ArteriesABSTRACT
BACKGROUND: Heart rate variability (HRV) is characterized by a variety of linear, non-linear, periodic and non-periodic oscillations. The aim of the present study was mainly to investigate the characteristics of nonlinear dynamics of HRV of the hypertensive patients by anesthesia comparing with the normotensive patients. METHODS: With informed consent, unpremedicated normotensive (n=20) and the hypertensive patients (n=22) were included in this study. ECG data were collected from 10 minutes before induction to 15 minutes after induction. Collected ECG data were stored into computer binary files. We calculated correlation dimensions (CD, degree of freedom of system), 1/f noise (beta, nonlinearity) and Hurst exponents (HE, roughness of signals) from the collected ECG data. RESULTS: During resting state, CD of the hypertensive patients was significantly lower than that of the normotensive patients (P<0.05). During maintenance of anesthesia, there was no difference of CD between the two groups. CD of two groups were decreased significantly after anesthesia (P<0.001). The values of and HE of two groups were not different during resting state and maintenance of anesthesia. But the values of and HE of two groups were increased significantly after anesthesia (P<0.001). CONCLUSION: As the CD of the hypertensive patients is lower than of the normotensive patients during resting state, the degree of freedom of heart rate control system of the hypertensive patients is more smaller than that of the normotensive patients. Decreasing of CD after anesthesia in two groups means that degree of freedom of heart rate control system is decreased by anesthesia. Increasing of 1/f noise after anesthesia in two groups means that nonlinearity of heart rate variability is decreased by anesthesia. Increasing of HE after anesthesia in two groups means that roughness of heart rate variability is decreased by anesthesia.
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Humans , Anesthesia , Electrocardiography , Freedom , Heart Rate , Heart , Informed Consent , Noise , Nonlinear DynamicsABSTRACT
BACKGROUND: It has been reported that sudden cardiac death can occur in postoperative tetralogy of Fallot (TOF) and this episode is related to the sustained ventricular tachyarrhythmia. However, the connecting mechanism of various clinical features and sudden cardiac death is not defined yet. Based on the reports that sudden cardiac death is related to the alteration of heart rate dynamics in some diseases, investigation of heart rate dynamics in postoperative TOF seems important to reveal the mechanism of sudden cardiac death. This study was done as a part of the project to investigate the alteration of heart rate variability and to identify the factors related to the sudden cardiac death in postoperative TOF. METHODS: Among the children with postoperative TOF, 13 asymptomatic children without significant hemodynamic disturbances (Doppler velocity for tricuspid regurgitation 2.5m/sec and mild pulmonary regurgitation) and ventricular arrhythmia were selected (10 boys, 3 girls; mean age, 9 year 3 months; mean duration after operation, 7 years). We evaluated the complexity and periodic dynamics of heart rate (HR) throughout 24 hours in these children and control group (mean age, 8 year 10 months). After examining each ECG data on 24-hour Holter ECG segmented into 1-hour length, we analyzed each HR time series and quantified the overall complexity of each HR time series by its correlation dimension. In addition, the power spectrum of HR and obtained low-frequency component (0.08-0.15Hz) and high-frequency component (0.15-0.4Hz) were calculated. RESULTS: This study showed that TOF group had lower correlation dimension and a nonlinear characteristics of HR time series than control group (4.055+/-0.4134 vs. 4.9310+/-0.2054, p<0.05). However, the difference was not significant in the low- (0.9864+/-0.5598 vs. 1.5560+/-0.8325, p<0.05) and high- (1.1168+/-0.1.1448 vs. 0.9271+/-0.6528, p<0.05) frequency components. CONCLUSIONS: It can be concluded that HR time series are more regular in postoperative TOF. The result was significant in correlation dimension analysis and not in the frequency domain analysis. Although the meaning of this finding in postoperative TOF is not clear at present, this may suggest the phenomenon related to the sudden cardiac death.
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Child , Female , Humans , Arrhythmias, Cardiac , Death, Sudden, Cardiac , Electrocardiography , Heart Rate , Heart , Hemodynamics , Tachycardia , Tetralogy of Fallot , Tricuspid Valve InsufficiencyABSTRACT
BACKGROUND: It has been reported that sudden cardiac death can occur in postoperative tetralogy of Fallot (TOF) and this episode is related to the sustained ventricular tachyarrhythmia. However, the connecting mechanism of various clinical features and sudden cardiac death is not defined yet. Based on the reports that sudden cardiac death is related to the alteration of heart rate dynamics in some diseases, investigation of heart rate dynamics in postoperative TOF seems important to reveal the mechanism of sudden cardiac death. This study was done as a part of the project to investigate the alteration of heart rate variability and to identify the factors related to the sudden cardiac death in postoperative TOF. METHODS: Among the children with postoperative TOF, 13 asymptomatic children without significant hemodynamic disturbances (Doppler velocity for tricuspid regurgitation 2.5m/sec and mild pulmonary regurgitation) and ventricular arrhythmia were selected (10 boys, 3 girls; mean age, 9 year 3 months; mean duration after operation, 7 years). We evaluated the complexity and periodic dynamics of heart rate (HR) throughout 24 hours in these children and control group (mean age, 8 year 10 months). After examining each ECG data on 24-hour Holter ECG segmented into 1-hour length, we analyzed each HR time series and quantified the overall complexity of each HR time series by its correlation dimension. In addition, the power spectrum of HR and obtained low-frequency component (0.08-0.15Hz) and high-frequency component (0.15-0.4Hz) were calculated. RESULTS: This study showed that TOF group had lower correlation dimension and a nonlinear characteristics of HR time series than control group (4.055+/-0.4134 vs. 4.9310+/-0.2054, p<0.05). However, the difference was not significant in the low- (0.9864+/-0.5598 vs. 1.5560+/-0.8325, p<0.05) and high- (1.1168+/-0.1.1448 vs. 0.9271+/-0.6528, p<0.05) frequency components. CONCLUSIONS: It can be concluded that HR time series are more regular in postoperative TOF. The result was significant in correlation dimension analysis and not in the frequency domain analysis. Although the meaning of this finding in postoperative TOF is not clear at present, this may suggest the phenomenon related to the sudden cardiac death.
Subject(s)
Child , Female , Humans , Arrhythmias, Cardiac , Death, Sudden, Cardiac , Electrocardiography , Heart Rate , Heart , Hemodynamics , Tachycardia , Tetralogy of Fallot , Tricuspid Valve InsufficiencyABSTRACT
The changes of electroencephalogram(EEG) in patients with dementia are most commonly studied by analyzing power or magnitude in certain traditionally defined frequency bands. However because of the absence of on identified metric which quantifies the complex amount of information, there are many limitations in using such a linear method. According to chaos theory, irregular signals of EEG cal also result from low dimensional deterministic chaos. Chaotic nonlinear dynamics in the EEG can be studied by calculating the correlation dimension. The authors have analyzed EEG epochs from three patients with dementia of Alzheimer type and three matched control subject. The result showed that patients with dementia of Alzheimer type had significantly lower correlation dimension than non-demented controls on 12 channels. Topographic analysis showed that the correlation dimensions were significantly lower in patients with Alzheimer's disease on frontal, temporal, central, and occipital head regions. These results show that brains of patients with dementia with dementia of Alzheimer type have a decreased complexity of electrophysiological behavior. We conclude that the nonlinear analysis such as calculating correlation dimension can be a promising tool for detecting changes in the complexity of brain dynamics.
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Humans , Alzheimer Disease , Brain , Dementia , Electroencephalography , Head , Nonlinear DynamicsABSTRACT
Based on the high-dimension chaos characteristics of electroencephalogram(EEG) and the analysis by the multi-variable state space reconstruction,better estimation of the correlative dimension can be obtained by dividing the brain into two parts and using eight EEG channels as the reconstruction samples.Lorenz system was firstly tested by request of the amount of data to test the feasibility of the algorithms.After Comparing the high-dimension data of the EEG of epileptic patients with the results of control subjects,it is indicated that the multi-variable state space reconstruction is applicable in short time noise-containing time sequences to obtain reliable results and can free the researchers from the hard choice of delay time and embedding dimension.
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Objective To study the effect of inhalational anesthetics on brain cortices under inhalational and intravenous combined anesthesia. Methods 45 patients were randomly divided into isoflurane group (n=15), sevoflurane group (n=15) and desoflurane group (n=15). The narcosis was maintained with inhalational and intravenous combined anesthesia. The EEG non-linear parameters including approximate entropy (ApEn) and correlation dimension (D 2 ) were recorded during operation periods. BP, HR, and SpO 2 were monitored routinely. Results Comparing with that at entrance to the operating room, the EEG activities of frontal and temporal cortices after anesthesia were more suppressed than other cortices. Comparing with that at entrance to the operating room, ApEn and D 2 were significantly declined in the three experimental groups (P
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Objective To study effect of propofol on different areas of brain cortex under total intravenous propofol and fentanyl anesthesia. Methods 20 patients were randomly divided into propofol 8mg/(kg?h) group (n=10) and 10mg/(kg?h) group (n=10). The anesthesia was maintained by total intravenous propofol and fentanyl anesthesia. The EEG non-linear parameters, i.e. approximate entropy (ApEn)and correlation dimension (D 2), were recorded during perioperative periods. BP, HR, SpO 2 were monitored routinely. Results Compared with that at entry of OR, the EEG activities of frontal, parietal, and temporal cortices after anesthesia were more inhibited than that of other areas in both groups. Also EEG non-linear parameters were lower significantly after anesthesia in both groups compared with those at entry of OR (P