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Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

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Updated November 12, 2011

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Atrioventricular nodal reentrant tachycardia (AVNRT) is a type of abnormal heart beat. It is the most common type of supraventricular tachycardia (SVT), accounting for about 60% of all SVTs.

AVNRT is known as a reentrant tachycardia. As with all reentrant SVT, patients with AVNRT have been 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 the tiny atrioventricular node (AV node).

The symptoms of AVNRT are typical for SVT, and generally include a sudden onset of palpitations, lightheadedness, and/or dizziness. Episodes commonly last from a few minutes to several hours.

The reentrant circuit in AVNRT is enclosed within the AV node, a structure that is richly supplied by the vagus nerve. So patients with AVNRT can often stop episodes by taking steps to increase the tone of their vagus nerve, such as the Valsalva maneuver, or immersing their face in ice water for a few seconds.

Using antiarrhythmic drugs to prevent recurrent AVNRT is often only moderately effective. However, AVNRT can usually (more than 95% of the time) be cured with ablation therapy, in which the abnormal electrical connection within the AV node is carefully mapped and ablated.

Source:

Denes P, Wu D, Dhingra R, et al. Dual atrioventricular nodal pathways. A common electrophysiological response. Br Heart J 1975; 37:1069.

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