Atrioventricular nodal reentry tachycardia (AVNRT)

Atrioventricular nodal reentry tachycardia, a form of supraventricular tachycardia, is the most common narrow-complex tachycardic arrhythmia in healthy individuals and only second to atrial fibrillation and atrial flutter in the general population.

Atrioventricular nodal reentry tachycardia (AVNRT) occurs when there is "dual AV nodal physiology" or a "dual AV node." This means there is one pathway that conducts slowly within the AV node and another that conducts quickly. A premature atrial contraction (PAC) or premature ventricular contraction (PVC) can alter the normal conduction cycle to produce a reentrant circuit within these two pathways, resulting in the tachycardia.

AVNRT-Initiation-Strip

Initiation of AVNRT with a PVC

Unlike atrial fibrillation and atrial flutter, AVNRT does not have any thromboembolic risk and is considered a relatively benign arrhythmia.

Diagnosis is made on the 12-lead ECG. Findings include a narrow complex tachycardia, a P wave that occurs after the QRS complex (a short RP interval) and termination with adenosine or carotid massage. See the AVNRT ECG Review for more details.

Treatment for atrioventricular nodal reentry tachycardia includes vagal maneuvers, which can frequently terminate the arrhythmia. Also, AV blocking agents such as beta-blockers and non-dihydropyridine calcium channel blockers (diltiazem or verapamil) can help to decrease the frequency of episodes. The usual approach to the treatment of AVNRT is medical therapy with AV blocking agents and referral for ablation if this therapy fails or significant side-effects occur. 

Ablation is commonly utilized, as the success rate is high with a low complication rate; however, it is considered to be most appropriate when medical therapy fails to control symptoms.