PR interval

Cite this article as:
Tessa Davis. PR interval, Don't Forget the Bubbles, 2014. Available at:


ECG intervals


PR interval


Prolonged PR interval (first degree heart block) may be normal or be seen in:

  • Viral or rheumatic myocarditis and other myocardial dysfunctions
  • Certain congenital heart disease (Ebsteins, ECD, ASD)
  • Digitalis toxicity
  • Hyperkalaemia

Short PR interval occurs in:

  • Pre‐excitation (eg Wolff‐Parkinson‐White)
  • Glycogen storage disease


Variable PR interval occurs in:

  • Wandering atrial pacemaker
  • Wenckebach (Mobitz type 1) second degree heart block.