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.