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:
- 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.