User`s guide

How the PageWriter 200/300pi Measures ECGs
3-4 Understanding ECG Analysis and the Predictive Instruments Applications
Figure 3-2: ECG Morphology Measurements
Waveform Recognition
The first step of the measurement program involves waveform recognition
and beat detection. A boundary indicator waveform in which QRS complexes
and pacemaker spikes are enhanced is derived from all leads over the ten-sec-
ond analysis period. After the approximate QRS complex and pacemaker
spike locations are known, another boundary indicator waveform that
enhances P and T wave detection is derived. Approximate P wave, QRS com-
plex and T wave regions are then determined for each beat in the ECG.
Comprehensive Measurements
After the approximate waveform locations are known, they are further refined
to determine precise onsets and offsets for each waveform. Once onsets and
offsets are known, amplitude, duration, area and shape are calculated for
every P wave, QRS complex, T wave and ST segment in every lead that you
see on the Auto 3 x 4 report. Waveform irregularities such as notches, slurs,
delta waves and pacemaker spikes are also noted for every beat. A table of all