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Third degree (complete) atrioventricular block

William H Sauer, MD
Section Editor
Leonard I Ganz, MD, FHRS, FACC
Deputy Editor
Brian C Downey, MD, FACC


Atrioventricular (AV) block is defined as a delay or interruption in the transmission of an impulse from the atria to the ventricles due to an anatomical or functional impairment in the conduction system. The conduction disturbance can be transient or permanent, with conduction that is delayed, intermittent, or absent. Commonly used terminology includes:

First degree AV block – Slowed conduction without missed beats.

Second degree AV block – Missed beats, often in a regular pattern (eg, 2:1, 3:2), or higher degrees of block, which is further classified into Mobitz type I (Wenkebach) and Mobitz II AV block.

Third degree (complete AV) block – No atrial impulses reach the ventricle.

High-grade AV block – Two or more consecutive blocked P waves.

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Literature review current through: Nov 2017. | This topic last updated: Aug 10, 2015.
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