Figure 1.
A typical ECG trace of the cardiac cycle (heartbeat) consists of a P wave, a QRS complex, and a T wave.
Figure 2.
QRS enhancement stage in ECG signals.
(a) ECG signal (top: from record 100 of the MIT-BIH Arrhythmia Database [62]), (b) amplitude from Eq.1 where , (c) first derivative from Eq.4, (d) first derivative and second derivative from Eq.7, and (e) digital filter from Ref. [33]. Signal amplitudes have been manipulated to fit all signals in one figure. Here, a red asterisk represents the annotated R peak.
Table 1.
Comparison of QRS enhancement techniques based on algorithm usage and assessment criteria.
Figure 3.
A filter bank contains a set of analysis filters that decompose the input signal into sub-bands with uniform bandwidths in order to extract ECG features. Here,
is a downsampling process producing down-sampled signals
.
Table 2.
Comparison of QRS detection techniques based on algorithm usage and assessment criteria.
Table 3.
Comparison of ECG beat detection algorithms based on techniques for QRS enhancement and detection on the MIT-BIH arrhythmia database [62].
Figure 4.
Screenshot showing the main interface of the ‘Hearty’ application implemented by Gradl et al. (2012) [8].
From top to bottom: Panel showing various clinically relevant parameters that are automatically detected including heart rate (HR) and RR interval; Panel showing the detected ECG signal, which is wirelessly streamed to the application; Panel showing the QRS detection with filled circle markers for the Q, R and S waves; Panel showing the detected beat-to-beat heart rate.
Figure 5.
A showcase of realtime factors for three outdated mobile phones.
Three QRS detection algorithms were tested, as reported by Sufi et al. [63]. The QRS enhancement phase was based on amplitude, first-derivative, and second-derivative techniques, whilst the QRS detection phase employed thresholding. Realtime factor is the processing time needed to run the QRS detection algorithm for an individual ECG entry within one measurement window size of 60 seconds.
Figure 6.
QRS enhancement stage in ECG signals.
(a) ECG signal (top: from record 107, bottom: from record 108 of the MIT-BIH Arrhythmia Database [62]), (b) amplitude from Eq.1 where , (c) first derivative from Eq.4, (d) first derivative and second derivative from Eq.7, and (e) digital filter from Ref. [33]. Signal amplitudes have been manipulated to fit all signals in one figure. Here, a red asterisk represents the annotated R peak.