Towards a portable device for real-time nonlinear characterization of heart dynamics

In this paper a first prototype towards a real-time portable device for ECG characterization in clinical applications is proposed. It consists of a hybrid hardware system supporting a novel methodology for real-time nonlinear characterization of time series. The analog sub-system performs the ECG signal conditioning in the simplest three-lead configuration providing as output a differential signal, suitably filtered and amplified. The digital subsystem is a microcontroller-based architecture for nonlinear signal processing. It implements a numerical algorithm which extracts the value of d_infin (d-infinite) and the maximum Lyapunov exponent, as indicators of chaotic behavior in ECG time series. Both the analog and the digital sub-systems have been successfully tested, proving their suitability for application in clinical studies.