Third Degree AV Block or Complete AV Block


Atrial rate is usually normal; ventricular rate is usually less than 70/bpm. The atrial rate is always faster than the ventricular rate.

P wave

Normal with constant P-P intervals, but not "married" to the QRS complexes.


May be normal or widened depending on where the escape pacemaker is located in the conduction system


Atrial and ventricular activities are unrelated due to the complete blocking of the atrial impulses to the ventricles.



Complete block of the atrial impulses occurs at the A-V junction, common bundle or bilateral bundle branches.

Another pacemaker distal to the block takes over in order to activate the ventricles or ventricular standstill will occur.

May be caused by:

Treatment modalities include:

Instant Feedback:

In a third degree heart block, the P waves are "married" to the QRS complexes.