Atrioventricular reentrant tachycardia. Atrioventricular Re-entry Tachycardia (AVRT) is a type of paroxysmal supraventricular tachycardia (PSVT) caused by accessory pathways. It involves a re-entry circuit between the AV node and the accessory pathway. There are two types: orthodromic AVRT (narrow complex rhythm) and antidromic AVRT (wide complex rhythm). Coumel’s sign helps differentiate between orthodromic AVRT and AVNRT. In typical AVNRT, retrograde P waves occur early, while in AVRT, they oc