Computation of Nonlinear Parameters of Heart Rhythm Using Short Time ECG Segments

Abstract

We propose the method to compute the nonlinear parameters of heart rhythm (correlation dimension D 2 and correlation entropy K 2) using 5-minute ECG recordings preferred for screening of population. Conversion of RR intervals' time series into continuous function x(t) allows getting the new time series with different sampling rate dt. It has been shown that for all dt (250, 200, 125, and 100 ms) the cross-plots of D 2 and K 2 against embedding dimension m for phase-space reconstruction start to level off at m = 9. The sample size N at different sampling rates varied from 1200 at dt = 250 ms to 3000 at dt = 100 ms. Along with, the D 2 and K 2 means were not statistically different; that is, the sampling rate did not influence the results. We tested the feasibility of the method in two models: nonlinear heart rhythm dynamics in different states of autonomous nervous system and age-related characteristics of nonlinear parameters. According to the acquired data, the heart rhythm is more complex in childhood and adolescence with more influential parasympathetic influence against the background of elevated activity of sympathetic autonomous nervous system.

Non-linear analysis of heart rate variability for evaluating the acute effects of caffeinated beverages in young adults

“…Entropy is the measure of the degree to which the occurrence of a value depends on its predecessors in the input. 11 High values of the entropy indicate high irregularity and complexity in time series data. 9 In our study, we found an increment in approximate entropy values of the experimental groups when compared with pre-drink values for 30 and 60 minutes of caffeinated beverage consumption.…”

“…To overcome this adequacy, non-linear methods are being used extensively. For instance, Koichubekov et al, 11 Pivatelli et al, 12 and Neves et al 13 analysed heart rate variability by evaluating the non-linear indices, such as largest Lyapunov exponent, approximate entropy and correlation dimension in patients with hypertension, stable angina, and coronary disease, respectively. Also, Tsai et al reported that detrended fluctuation analysis shown better predictive ability for clinical outcomes when compared to traditional heart rate variability analysis methods.…”

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“…There is also an inverse relationship with age with higher values in adolescent group (8 to 17 years) and lesser values starting with age group of 22 to 35 years due to increased sympathetic activity [29] . …”

Evaluation of extrapolation methods for actual state expenditures on health care in Russian Federation

“…Вопросы использования математико-статистических методов экстраполяции финансового положения финансовой устойчивости/нестабильности здравоохранения остаются открыты. Если в клинических исследованиях данные методы прогноза находят свое применение [6,7], и здесь можно встретить такие выражения как «неясность условий экстраполяции» (URL: http://medicalplanet.su/Patfiz/913.html), то в вопросах финансирования здравоохранения -нет.…”