Atrioventricular block classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Edzel Lorraine Co, DMD, MD[2]

Atrioventricular (AV) block is a medical condition wherein there is a disturbance in the conduction of an electro-cardiac impulse traveling from the atria to the ventricle, as a result of an anatomic or functional aberration in the conduction system. It is classified into three types, which are the first degree AV block, second-degree AV block, and third-degree AV block/complete AV block.

• First degree AV block
  • Prolongation of PR interval of more than 200 milliseconds
• Second degree AV block also known as Mobitz I and Mobitz II
  • Type I AV Block (Wenckebach)
    • Progressive prolongation of the PR interval before dropped beat.
    • Usually block is in the AV node
  • Type II AV Block
    • No change in PR interval before dropped beat
    • Usually infranodal
• Third degree AV block also known as complete heart block
  • No relationship between atrial and ventricular activity.

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