In this new monthly section, authors provide five tips on solving common concerns in the EP lab. In this month’s column, the author provides five ways to identify and diagnose AV nodal reentry tachycardia (AVNRT).

1. Sudden onset/sudden termination: Often a patient will describe tachycardia as starting and stopping abruptly. This suggests a reentrant tachycardia.

Figure 1.

Retrograde P waves in inferior leads during tachycardia: A 12-lead ECG of the tachycardia (left) may have shallow S waves in the inferior leads (II, III, aVF) that are not present in a baseline ECG (right). One may also see an RR’ pattern in Lead V1. These 12-lead ECG features are generated by the retrograde P-wave during tachycardia.

2. Retrograde P waves in inferior leads during tachycardia: A 12-lead electrocardiogram (ECG) of the tachycardia (Figure 1) may have shallow S waves in the inferior leads (II, III, aVF) that are not present in a baseline ECG (Figure 2). One may also see an RR’ pattern in Lead V1. These 12-lead ECG features are generated by the retrograde P-wave during tachycardia.

Figure 2.

Retrograde P waves in inferior leads during tachycardia: A 12-lead ECG of the tachycardia (left) may have shallow S waves in the inferior leads (II, III, aVF) that are not present in a baseline ECG (right). One may also see an RR’ pattern in Lead V1. These 12-lead ECG features are generated by the retrograde P-wave during tachycardia.

3. AH “jump”: An AH interval “jump” of greater than 50 ms during atrial single extrastimulus programmed stimulation indicates dual AV node physiology (there are two pathways in the AV node — fast and slow). (Figure 3)

Figure 3.

AH “jump”: An AH interval “jump” of greater than 50 ms during atrial single extrastimulus programmed stimulation. This phenomenon indicates dual AV node physiology (two pathways in the AV node - fast and slow).

4. Midline, decremental VA conduction: This type of VA conduction strongly suggests AV node involvement. It is quite rare to have AVNRT without VA conduction.

Figure 4.

All internal electrograms line up during tachycardia: The appearance of all internal electrograms lining up with each other suggests typical AVNRT (right side of tracings). One must still rule out a septal bypass tract before a definitive diagnosis can be made.

5. All internal electrograms line up during tachycardia: The appearance of all internal electrograms lining up with each other suggests typical AVNRT (Figure 4). One must still rule out a septal bypass tract, though, before a definitive diagnosis can be made.


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