Atrioventricular nodal reentry tachycardia (AVNRT) is a paroxysmal supraventricular tachycardia (PSVT) caused by a reentrant pathway within the atrioventricular (AV) node resulting in a regular tachycardia (120-200 beats per minute [bpm]). Symptom onset and termination is usually abrupt.

AVNRT is caused by a short circuit loop created by the existence of 2 electrical pathways within the AV node termed the "fast" and "slow" pathways. "Typical" AVNRT refers to antegrade conduction down the slow pathway, with the fast pathway serving as the retrograde limb. "Atypical" AVNRT involves antegrade conduction down the fast pathway, and the slow pathway serves as the retrograde limb.

AVNRT is more common in women than men. Patients usually present after 20 years of age, with a mean age of onset of 32 years old. AVNRT makes up two-thirds of all PSVTs.

In most cases, there is no apparent precipitating cause or trigger for episodes of AVNRT. However, in some patients, nicotine, alcohol, stimulants, exercise, activities, or medications may contribute, possibly by increasing vagal tone.