AV nodal reentrant tachycardia
AV nodal reentrant tachycardia is the most common paroxysmal supraventricular tachycardia, a reentry circuit within the AV node using slow and fast pathways, producing an abrupt regular narrow-complex tachycardia with P waves buried in or just after the QRS. Acute treatment is vagal maneuvers then adenosine, and slow-pathway catheter ablation is curative.
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What this article covers
- Overview
Definition: AV nodal reentrant tachycardia (AVNRT) is a supraventricular tachycardia caused by a reentry circuit within or adjacent to the AV node using functionally distinct slow and fast pathways.
- Epidemiology
The commonest paroxysmal SVT, more frequent in women.
- Risk factors
Dual AV nodal physiology (slow and fast pathways), the anatomic substrate.
- Pathophysiology
Dual pathways: the AV node region has a slow pathway (slow conduction, short refractoriness) and a fast pathway (fast conduction, long refractoriness).
- Clinical features
Abrupt palpitations: sudden onset and offset, regular and rapid.
- Differential diagnosis
AV reentrant tachycardia (AVRT): accessory-pathway reentry with a retrograde P wave later in the ST segment, distinguished from AVNRT by a longer RP interval and, unlike AVNRT, an accessory pathway…
- Diagnosis
Establish with an ECG showing a regular narrow-complex tachycardia with P waves buried in or immediately after the QRS: the diagnostic basis is a 12-lead ECG demonstrating a regular narrow-QRS…
- Management
First, vagal maneuvers: modified Valsalva or carotid sinus massage to terminate the tachycardia.
- Complications
Recurrent symptomatic episodes. Hemodynamic compromise or syncope at very rapid rates.
- Prognosis
Excellent: benign with an excellent prognosis, and ablation is curative in the large majority.
- Prevention
Avoid triggers: caffeine, stimulants, and alcohol.
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Related articles
- Paroxysmal supraventricular tachycardia
Paroxysmal supraventricular tachycardia is a sudden-onset, regular narrow-complex tachycardia from a reentrant circuit involving the AV node (AVNRT) or an accessory pathway (AVRT), presenting with abrupt palpitations. Acute treatment is vagal maneuvers then adenosine, unstable patients receive synchronized cardioversion, and catheter ablation is a curative long-term option.
- Supraventricular tachycardia
Supraventricular tachycardia is any tachyarrhythmia arising at or above the AV node, usually a regular narrow-complex tachycardia. Acute management of a stable regular narrow-complex SVT is vagal maneuvers then adenosine; unstable patients receive synchronized cardioversion, and definitive therapy is catheter ablation.
- Wolff-Parkinson-White (WPW) syndrome
Wolff-Parkinson-White syndrome is ventricular pre-excitation via an accessory pathway plus symptomatic tachyarrhythmia, marked on the resting ECG by a short PR interval and a delta wave. Its danger is pre-excited atrial fibrillation, which can conduct rapidly to the ventricles and degenerate into ventricular fibrillation; AV nodal blockers are contraindicated in that setting, and catheter ablation of the pathway is curative.