P wave (electrocardiography)

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P wave in the ECG represents atrial depolarization, which causes atrial contraction.

Absence of the P wave may indicate:


Peaked p waves (>2.5mm) indicate right atrial enlargement(P pulmonale).[1]

A P wave with increased amplitude can indicate hypokalemia.[2] It can also indicate right atrial enlargement.[3]

A P wave with decreased amplitude can indicate hyperkalemia.


Bifid p waves indicate left-atrial hypertrophy (P mitrale),[1] whereas a sawtooth-form P wave may indicate atrial flutter.

If P waves are not clearly delineated in the surface ECG, Lewis lead may be used to better visualize P waves.

Related pages[edit]


  1. ^ a b c d Longmore, Murray (2004). Oxford Handbook of Clinical Medicine 8th edition page 90. Oxford University Press. ISBN 0-19-852558-3. 
  2. ^ http://www.uhmc.sunysb.edu/internalmed/nephro/webpages/Part_D.htm
  3. ^ http://library.med.utah.edu/kw/ecg/ecg_outline/Lesson7/index.html