P-wave complexity in normal subjects and computer models.

Background: P waves reported in electrocardiology literature uniformly appear smooth. Computer simulation and signal analysis studies have shown much more complex shapes. Objective: We systematically investigated P-wave complexity in normal volunteers using high-fidelity electrocardiographic techniques without filtering. Methods: We recorded 5-min multichannel ECGs in 16 healthy volunteers. Noise and interference were reduced by averaging over 300 beats per recording. In addition, normal P waves were simulated with a realistic model of the human atria. Results: Measured P waves had an average of 4.1 peaks (range 1–10) that were reproducible between recordings. Simulated P waves demonstrated similar complexity, which was related to structural discontinuities in the computer model of the atria. Conclusion: The true shape of the P wave is very irregular and is best seen in ECGs averaged over many beats.