AV reentrant tachycardia

AVRT results from an anatomically distinct atrioventricular connection. The causes, which usually are congenital or genetic, include: Ebstein anomaly, Lown-Ganong-Levine syndrome, Mahaim fiber tachycardia, Wolff-Parkinson-White syndrome.

Two types of tachycardia fall under this category:

In orthodromic AVRT, the antegrade conduction (from the atria to the ventricles) occurs through the AV node, whereas the retrograde conduction (from the ventricle to the atrium) occurs through the accessory pathway. In this case, the ECG will reveal narrow QRS and retrograde P wave following the QRS complex.

In antidromic AVRT, the antegrade conduction (from the atrium to the ventricle) occurs through the accessory pathway, whereas the retrograde conduction (from the ventricles to the atria) occurs through the AV node. In this case, the ECG will reveal wide QRS similar to those found in ventricular tachycardia.

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

AV nodal reentrant tachycardia is usually not life-threatening.

• Mitral valve prolapse

• Ebstein anomaly
• Lown-Ganong-Levine syndrome
• Mahaim fiber tachycardia
• Wolff-Parkinson-White syndrome

Electrical activity of the heart is rerouted through an accessory pathway that connects the atria with the ventricles.

The appearance of QRS alternans as part of a narrow complex tachycardia suggests the diagnosis of orthodromic atrioventricular (AV) reentrant tachycardia which conducts retrograde over an accessory pathway.

Below is a video explaining the mechanism of AV re-entrant tachycardia

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Wolff-Parkinson-White syndrome Lown-Ganong-Levine syndrome

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