Atrioventricular Nodal Reentrant Tachycardia (AVNRT) Overview

Woman with heart palpitations

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Atrioventricular nodal reentrant tachycardia (AVNRT) is a rapid, regular cardiac arrhythmia that starts suddenly and without warning, and stops just as suddenly. It most commonly affects younger adults. The average age at which AVNRT first occurs is 32, and most people with this arrhythmia will have their first episode by age 40. Once it first happens, it tends to become a recurrent problem.


AVNRT is the most common type of supraventricular tachycardia (SVT), accounting for about 60 percent of all SVTs.

AVNRT is one of the reentrant tachycardias. (“Tachycardia” simply means rapid heart rate.) With every reentrant tachycardia, there is an abnormal electrical connection somewhere in the heart, that forms a potential electrical circuit.

When one of the heart’s electrical impulses enters this potential circuit under just the right circumstances, it can become “captured” within the circuit which means it starts spinning around and around the circuit. Every time it travels around the circuit, the electrical impulse produces a new heartbeat and tachycardia results.

As is the case with most reentrant SVTs, patients with AVNRT are born with an extra electrical connection in the heart. In AVNRT, the extra connection and the entire reentrant circuit that produces the arrhythmia is located within or very close to the tiny atrioventricular node (AV node). Hence the name—AV nodal reentrant tachycardia.


The symptoms of AVNRT are typical for SVT, and generally include a sudden onset of palpitations, lightheadedness, and/or dizziness. Shortness of breath is also fairly common in this arrhythmia.

One symptom that is often seen in AVNRT that occurs less frequently with other kinds of SVT is a sensation of pounding in the neck. This symptom occurs because, during episodes of AVNRT, the atria and the ventricles are beating at the same time. Because the atria cannot eject their blood into the ventricles, the blood is pushed upwards into the neck vein—and a pounding sensation results.

Episodes of AVNRT start and stop quite suddenly, and they commonly last from a few minutes to several hours.

Starting and Stopping AVNRT

The AV node is very sensitive to changes in the autonomic nervous system, the part of the nervous system that controls blood vessels and internal organs. So changes in either sympathetic nervous tone (a stress response) or in the tone of the vagus nerve (parasympathetic tone, or a relaxation response) can have a major effect on the AV node.

Because much of the reentrant circuit in AVNRT is contained within the AV node, changes in the autonomic tone can have a profound effect on the arrhythmia.

While AVNRT most commonly begins without any apparent triggers, in some people it can start with exercise or periods of emotional stress or other situations that increase sympathetic tone. In others, it can start during deep sleep, with squatting, or when suddenly bending forward — situations that increase vagal tone.

Patients with AVNRT can often stop their episodes of tachycardia by doing things to suddenly increase the tone of the vagus nerve. Performing the Valsalva maneuver often works, though more drastic steps (such as immersing their face in ice water for a few seconds) may sometimes be necessary.

Medical Treatment

Doctors can treat acute episodes of AVNRT fairly quickly and easily. First, they generally guide the patient through a few attempts at increasing their vagal tone. If that fails to stop the arrhythmia, an intravenous injection of adenosine or verapamil (a calcium blocker) will work quickly and reliably. The more difficult medical question regards long-term therapy for AVNRT.

Because the arrhythmia is not life-threatening, but “merely” life-disrupting, the aggressiveness of treatment ought to reflect how disruptive the arrhythmia is to the patient. If episodes are quite infrequent, reasonably well-tolerated, and can be terminated pretty reliably by vagal maneuvers, then likely nothing more needs to be done.

However, if episodes of AVNRT are disruptive to a patient’s life (which is often the case), then treatment ought to be strongly considered. Treatment with beta-blockers or calcium channel blockers is reasonably effective in reducing the frequency of AVNRT, and in most patients, one or both of these kinds of drugs is well tolerated.

If the arrhythmia is not sufficiently controlled, then one of the antiarrhythmic drugs might be tried. However, these drugs often have side effects, and they are only moderately effective in treating AVNRT.

The most effective means of treating AVNRT today is to use ablation therapy, a catheterization procedure. With ablation therapy, the abnormal electrical connection in or near the AV node is carefully mapped and then is ablated, usually with radiofrequency energy.

AVNRT can be completely cured with ablation therapy in over 95 percent of cases. So ablation should be strongly considered by anyone in whom AVNRT is a major problem, especially if it has not been controlled using beta-blockers or calcium blockers.

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