Atrioventricular Nodal Reentry Tachycardia Differential Diagnoses

Updated: Nov 19, 2019
  • Author: Brian Olshansky, MD, FESC, FAHA, FACC, FHRS; Chief Editor: Jose M Dizon, MD  more...
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DDx

Diagnostic Considerations

Automatic or triggered atrial tachycardia

Automatic or triggered atrial tachycardia generally looks distinctly different, but it may have similar features to typical atrioventricular nodal reentry tachycardia (AVNRT) if it originates in the low atrial septal area and if 1:1 conduction occurs.

This is a focal tachycardia originating in the atria. It may or may not be associated with underlying heart disease. There may be AV block.

Multifocal atrial tachycardia

This is an irregular rhythm with at least three distinctly discernible P-wave morphologies. Multifocal atrial tachycardia is often associated with pulmonary disease or medications such as digoxin.

Bypass tract-mediated macroreentrant tachycardia

Electrocardiographic findings may show evidence of preexcitation (if there is antegrade conduction via the accessory pathway but this is often not present). Some bypass tracts do not demonstrate antegrade conduction, so baseline preexcitation is not present on the surface electrocardiogram (ECG). In orthodromic tachycardias (ie, due to a bypass tract), the P wave typically falls distinctly after the QRS complex, in contrast to the superimposition most commonly seen with AVNRT. In typical AVNRT, the P wave appears immediately in or after the QRS complex and, due to retrograde activation via the fast pathway, the P wave appears to be a “pseudo S wave" in leads II, III, aVF, as well as a “pseudo R wave" in lead V1 (see the image below).

Typical atrioventricular nodal (AV) reentry tachyc Typical atrioventricular nodal (AV) reentry tachycardia. In this electrocardiogram, the P wave appears immediately after or just within the QRS complex. Often a “pseudo R wave" is seen in lead V1 and a “pseudo S wave" in leads II, III, aVF. The retrograde P wave represents retrograde activation via the fast pathway, which is anterior septal and superior to the AV node.

Orthodromic AV-reciprocating tachycardia (AVRT) tends to occur at an earlier age and more frequently in males than AVNRT. In young males, AVRT tends to be a more rapid supraventricular tachycardia (SVT) than are most AVNRTs. Women tend to have a greater risk for AVNRT than for AVRT, but there is, nevertheless, a large overlap in the incidence of both conditions by age and sex.

Another potentially distinguishing factor in AVNRT is the sensation of neck pulsations. This is more common in AVNRT, as there is simultaneous atrial and ventricular activation and contraction. [6]

During the rapid SVTs, QRS alternans may occur. QRS alternans can occur during AVRT or AVNRT and is more related to rate than mechanism.

Sinus node reentrant tachycardia

Normal P waves precede the QRS (electrocardiographic) complex.

Intra-atrial reentry tachycardia

Abnormal P waves precede each QRS complex. There may be AV block

Atrial fibrillation

This is an irregular ventricular rhythm without P waves, due to dyssynchronous and variable atrial activation.

New-onset AVNRT has been observed after radiofrequency ablation involving the septum or proximal coronary sinus, which appears to indicate connections between the posteroseptal left atrium and the coronary sinus are essential for certain forms of AVNRT. [7]

Atrial flutter

Flutter waves are present. The atrial rhythm is rapid and regular. The ventricular rate can be variable but without treatment is approximately 150 bpm (with 2:1 AV block).

Automatic junctional tachycardia

This tachycardia originates from the AV node as an automatic rhythm. Atrioventricular dissociation may occur.

Differential Diagnoses