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
Normal sinus rhythm with a positive p wave in leads I, II en AVF and a biphasic p wave in V1.
Altered P wave morfology is seen in left or right atrial enlargement.
The PTa segment can be used to diagnose pericarditis or atrial infarction.

The P wave morphology can reveal right or left atrial stretch 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 bifasic in V1
  • The p wave duration is usually shorter than 0.12 seconds

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.