Re-entrant Arrhythmias

AVNRT (AV-nodal re-entry tachycardia)

Typical AVNRT
Atypical AVNRT

AVRT (atrioventricular re-entry tachycardia)

Orthodromic AVRT
Antidromic AVRT

Junctional Rhythm

– Narrow complex rhythm similar to sinus QRS complex with QRS duration < 120ms (unless aberrant conduction)
– Rhythm originates from the AV node or His bundle
– Retrograde P waves either before or after QRS or merged into QRS
– If seen, P waves are inverted in inferior leads (II, III, aVF) and upright in aVR + V1
– Types of JR based on rate:
Junctional bradycardia: rate < 40 BPM
Junction escape rhythm: rate 40 to 60 BPM
Accelerated junctional rhythm: rate of 60 to 100 BPM
Junctional tachycardia: rate > 100 BPM

Sinoatrial nodal reentrant tachycardia (SANRT)

– Rapid pulse and heartbeat on physical examination
– Sinus P waves with a rate between 100 and 150 BPM
– EP study is required to differentiate with inappropriate sinus tachycardia
– Abrupt onset and termination is a clue in favor of SANRT
– Episodes of SANRT vary in length (can last from few seconds to multiple hours)