RESUMO
Time irreversibility is a subject of increasing interest in biomedicine. However, measurements of this property have been limited to a two-dimensional state space and few effective methods for high-dimensional time irreversibility testing have been reported. Using a strategy based on multiple bidimensional tests, we propose an extension of the traditional low-dimensional method for the estimation of time irreversibility in a high-dimensional state space. The method is applied to both physiological and synthetic interbeat (RR) intervals and the results indicate that time irreversibility should be an intrinsic characteristic of human RR intervals and is complementary to the conventional properties that can be measured in the time and frequency domain. Furthermore, a loss of time irreversibility is detected when the method is applied to patients with congestive heart failure (CHF). Compared with the traditional time irreversibility test, the proposed method is not only capable of quantifying time irreversibility in a more reliable manner, but is also effective for analysis of short records of only a few minutes' length, which would be more useful clinically.
Assuntos
Testes de Função Cardíaca/métodos , Frequência Cardíaca , Adulto , Estudos de Casos e Controles , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Pessoa de Meia-IdadeRESUMO
This paper presents a novel monitor which uses ARM controller AT91SAM7S64 as its main processor, LCM (Liquid Crystal Display Module) for displaying ECG waves, SD (Secure Digital memory) card for data storage and RF module PTR8000 for radio data transmission. This portable monitor boasts alarm function for abnormality and can provide dynamic ECG monitoring for patients.
Assuntos
Redes de Comunicação de Computadores , Eletrocardiografia/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Telemetria/instrumentação , Humanos , Monitorização Fisiológica/instrumentação , Telemetria/métodosRESUMO
In this paper, a design of the portable acquisition system for autonomic nervous function data based on the microcontroller is introduced. The system contains an electrocardiogram amplifier and an AD convertor, using SD memory card as its storage device and thus it can record data for a longer time and exchange data with PC easily. The system with a simple structure realizes its miniaturization and low energy consumption.
