AV Nodal Reentrant Tachycardia (AVNRT)

When describing a supraventricular tachycardia that is due to a re-entrant circuit in the AV node specifically, it is better to use the term AVNRT as opposed to SVT in order to avoid confusion - Anand Swaminathan MD

AV Nodal Reentrant Tachycardia (AVNRT)
AV Nodal Reentrant Tachycardia (AVNRT)

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AV Nodal Reentrant Tachycardia (AVNRT)

AV nodal reentrant tachycardia, AVNRT, is the most common cause of supraventricular tachycardia (SVT). It is more common in women than in men and presents in all age groups. Patients with AVNRT have at least two pathways of tissue in their AV node that allows for an abnormal electrical circuit to perpetuate within their AV node. However, there are many individuals who have dual pathways of AV nodal tissue, but never have the electrical circuit perpetuate to develop sustained tachycardia. It is this spinning circuit that goes “round-and-round” enclosed in the AV node that allows for rapid stimulation of the ventricles through the normal His bundle, bundle branches, and ultimately Purkinje fibers…

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 AV Nodal Reentrant Tachycardia (AVNRT)

The symptoms of AVNRT are similar to other SVT, with palpitation, lightheadedness, dizziness, shortness of breath, reduced exercise capacity, weakness, fatigue, chest discomfort, and sweating episodes. These symptoms are primarily due to loss of atrioventricular synchrony (when then atria and ventricles no longer contract in a tightly-coupled progression) or the development of rapid and/or irregular ventricular rates.

ECG Stampede

Atrioventricular nodal reentrant tachycardia (AVNRT) is caused by a reentrant loop within the atrioventricular node. With AVNRT, the atrioventricular node has two pathways, fast and slow, which allows for a reentrant loop. The differential for a regular, narrow complex tachycardia includes sinus tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), atrial flutter, and atrial tachycardia. P waves can aid the diagnosis but are often absent. At faster rates, sinus tachycardia can be obscured when P waves are buried within the T waves. P waves in a sawtooth pattern favors atrial flutter (2:1 conduction usually has a ventricular response rate around 150 bpm). While most cases of AVNRT do not have visible P waves, up to one third of AVNRT cases will show retrograde P’ waves immediately following the QRS complex, giving the appearance of a “pseudo-S wave” in the inferior limb leads, or a “pseudo-R wave” in V1. Rarely, atypical “fast-slow” AVNRT can produce retrograde P’ waves that precede the QRS complex.

StatPearls

Atrioventricular nodal reentrant tachycardia (AVNRT) is a type of paroxysmal supraventricular tachycardia that results due to the presence of a re-entry circuit within or adjacent to the AV node. The diagnosis of AVNRT requires visualization of an electrocardiogram (ECG). In most cases, an ECG will show heart rate between 140 and 280 beats per minute (bpm), and in the absence of aberrant conduction, a QRS complex of fewer than 120 milliseconds.

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