'''Characteristics of a normal p wave:'''<cite>Spodick</cite>
*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 shorter than 0.12 seconds
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 [[Ischemia#Atrial infarction|Atrial infarction]] or [[Clinical Disorders#Pericarditis|pericarditis]].