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.