Junctional bradycardia pathophysiology

Junctional bradycardia or an AV junctional escape is a delayed heartbeat originating from an ectopic focus somewhere in the AV junction to compensate for an SA node that is no longer handling the pacemaking activity.

Normally, the atrioventricular node (AVN) can generate an escape rhythm of 40-60 beats per minute in case the sinoatrial node (SA node) or atrial pacemakers fail (sinus arrest) or slow (sinus bradycardia) or if there is complete heart block. This junctional escape rhythm generates a normal, narrow QRS complex rhythm at a rate below 60 beats per minute (junctional bradycardia) as the electrical impulses once they are generated are conducted with normal velocity down the usual pathways. Retrograde P waves (i.e. upside down) P waves due to retrograde or backward conduction may or may not be present.

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