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P-wave duration

Column: p_wave_duration_ms · Unit: ms · Measured on: lead II (default)

In one sentence: the P wave is the small bump before the main spike, made by the two upper chambers (the atria) activating; its duration is how long that takes.

Everyday picture

The P wave is the "starter" of each beat: the upper chambers give a small squeeze to top up the lower chambers before the main pump stroke. A longer P wave means the electrical wave takes longer to cross the upper chambers, for example because they are stretched.

Try it

Change the width and height of the P wave. Try No P wave too: without it there is nothing to measure.

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What to notice:

  • The P wave is small, usually well under a quarter of the R spike, so it is the first thing to disappear in noise.
  • No P wave means the beat did not start from the heart's normal pacemaker. In real ECGs this happens in some rhythm problems such as atrial fibrillation.

What's typical

P-wave duration Plain meaning
up to about 120 ms (3 small boxes) typical
longer than 120 ms the upper chambers take longer to activate, often because they are enlarged

Why it matters for synthetic ECGs

The P wave is easy for a generator to get wrong because it is small: it may be missing, smeared into the baseline, or merged into the QRS. A synthetic set that mostly lacks P waves does not represent normal (sinus) rhythm, even if every other part looks right.

How ECGEN-Eval measures it

p_wave_duration_ms is the time from P-wave start to P-wave end, median over beats. NeuroKit2's peak-prominence delineator finds the P wave on every lead. Its start and end are then moved in to where the wave reaches 15 % of its height, and the leads are combined with the median.

Needs NeuroKit2 (NaN without it). The P wave is small and its edges are gentle, so this is the least precise feature: against GE 12SL the typical error is 12 ms (r 0.41), and even two commercial programs only reach r 0.48 (validation).

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