P Wave Morphology

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«Step 4:Heart axis Step 6: QRS morphology»

Author(s) J.S.S.G. de Jong, MD, A. Bouhiouf, Msc
Moderator J.S.S.G. de Jong, MD
some notes about authorship

The Normal P wave

The P wave morphology can reveal right or left atrial hypertrophy or atrial arrhythmias and is best determined in leads II and V1 during sinus rhythm.

Characteristics of a normal p wave:[1]

  • The maximal height of the P wave is 2.5 mm in leads II and / or III
  • The p wave is positive in II and AVF, and biphasic in V1
  • The p wave duration is shorter than 0.12 seconds
An example of normal sinus rhythm.
center}Another example of normal sinus rhythm.

The Abnormal P wave

Elevation or depression of the PTa segment (the part between the p wave and the beginning of the QRS complex) can result from atrial infarction or pericarditis.

If the p-wave is enlarged, the atria are enlarged.

If the P wave is inverted, it is most likely an ectopic atrial rhythm not originating from the sinus node.

Altered P wave morphology is seen in left or right atrial enlargement.
The PTa segment can be used to diagnose pericarditis or atrial infarction.


  1. Spodick DH, Raju P, Bishop RL, and Rifkin RD. Operational definition of normal sinus heart rate. Am J Cardiol. 1992 May 1;69(14):1245-6. PubMed ID:1575201 | HubMed [Spodick]