A reentry arrhythmia involving 2+ pathways across the AV groove.

Usually begins with an ectopic (can be atrial or ventricular).

Can be terminated with vagal maneouvres or administration of Adenosine (AV nodal blocking agent).

May require ablation.

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AVNRT (AV nodal reentry tachycardia)

• Reentry circuit around the AV node

• Patient requires dual AV node physiology for the arrhythmia to occur

• Tachycardia may have intermittent lower common blcok where there are 2 atrial events for every 1 ventricular event, or upper common block (very rare) where there are 2 ventricular events for every 1 atrial event,

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There are 3 types of AVNRT

1. slow-fast: most common which involves antegrade conduction down the slow pathway and retrograde conduction up the fast pathway.

2. fast-slow: involves antegrade conduction down the fast pathway and retrograde conduction up the slow pathway.

3. Slow-slow: involves antegrade and retrograde conduction up/down 2 slow pathways.

 

AVRT (Atrioventricular reentry tachycardia)

• Reentry circuit which utilises an accessory pathway

• May utilise 2 accessory pathways or 1 accessory pathway with the AV node as the 2nd limb.

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There are 2 types of AVRT

1. Orthodromic: (most common) conduction goes down the AV node (often resulting in a narrow comlex unless aberrancy) and travels back to the atrium via the accessory pathway

2. Antidromic: conduction goes down the accessory pathway resulting in a broad, abnormal ventricular complex (often resembling VT) and back up to the atrium via the AV node.