Real-time PC-based system for dynamic beat-to-beat QT-RR analysis.
A real-time analysis (RTA) system, based on a personal computer with a digital signal processor card (DSP) was developed. The system extracts and saves the QT and RR intervals from an incoming ECG signal sampled at 1 kHz. The method of defining the QT and RR intervals is based on performing multiple cross-correlations that enables rejection of artifacts from the analysis. The relationship between the RR and the QT intervals is found using the following general formula QT(i) cRR(i)(i-1). Linear regression is performed on the logarithms of QT and RR measurements obtained to estimate a constant (a = logc) and a slope (b), reflecting the dynamic change of the QT intervals. Having these two values, the dynamic QT extrapolated to a heart period of 1 s (QTcd) was calculated. The system also performs spectral analysis of the intervals and dynamic QT-RR relation analysis. The system was evaluated on recordings from 10 infants aged 4 to 24 weeks. The QT/RR computerized measuring device used in the present study answers to the requirements for precise dynamic beat-to-beat QT measurement. Its sampling rate is high and can achieve a real millisecond-precision without the need of interpolation methods. The measurements are performed on-line, at the time of the actual recording. Results appear immediately and a measure of dynamic QT behavior can be easily obtained within minutes. The computerized system with the dynamic QT-RR measurements may provide a simple and accurate tool for testing drug treatment and effects of other interventions for cardiac disorders and arrhythmia risk.
Govreen-Segal
D
D
Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel.
Radai
M M
MM
Sivan
Y
Y
Abboud
S
S
D004562:Electrocardiography; D005069:Evaluation Studies as Topic; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008838:Microcomputers; D012044:Regression Analysis; D012815:Signal Processing, Computer-Assisted; D012984:Software; D012985:Software Design