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Atrioventricular nodal reentrant tachycardia (AVNRT)

Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

  • It is a rapid cardiac arrhythmia that starts suddenly and without warning and stops just as abruptly.
  • It most commonly affects younger adults and may become a recurrent problem once it first occurs.
  • AVNRT is the most common type of supraventricular tachycardia (SVT) in adults.
  • It is one of the reentrant tachycardias, caused by an abnormal electrical connection that forms a potential circuit in the heart.
  • When an impulse enters this circuit, it can get “trapped,” spinning repeatedly and triggering rapid heartbeats (tachycardia).
  • The reentrant circuit in AVNRT is located within or very close to the atrioventricular (AV) node.
AVNRT Diagram

AVNRT Symptoms

The symptoms of AVNRT are typical for SVT. They generally include one or more of the following:

Sudden onset of palpitations
Lightheadedness
Dizziness
Shortness of breath

One symptom that is often seen in AVNRT, but that occurs less frequently with other kinds of SVT, is a sensation of pounding in the neck.

During episodes of AVNRT, the atria and the ventricles are beating at the same time. Because the atria cannot eject blood into the ventricles, it is pushed upward into the neck vein—resulting in a pounding sensation.

Starting and Stopping AVNRT

AVNRT Start and Stop

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. Hence, 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, periods of emotional stress, or other situations that increase sympathetic tone. In others, it can start after ingesting alcohol, tea, or coffee. 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.