Real-time PC-based system for dynamic beat-to-beat QT-RR analysis

Dael Govreen-Segal*, Michal M. Radai, Yakov Sivan, Shimon Abboud

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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-1)/b. 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.

Original languageEnglish
Pages (from-to)336-354
Number of pages19
JournalComputers and Biomedical Research
Issue number4
StatePublished - Aug 1999


  • QT and RR intervals
  • Real-time ECG analyzer
  • Spectral analysis


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