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# Supraventricular tachycardia (AVNRT, AVRT)

Supraventricular tachycardia is a sudden fast, regular heartbeat that starts above the ventricles. It is usually not dangerous and can be cured.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Atrioventricular (AV) node](https://durgical.com/en/anatomy/atrioventricular-node/)
- [Right atrium](https://durgical.com/en/anatomy/right-atrium/)
- [Left atrium](https://durgical.com/en/anatomy/left-atrium/)
- [Sinoatrial (SA) node](https://durgical.com/en/anatomy/sinuatrial-node/)
- [Bundle of His](https://durgical.com/en/anatomy/atrioventricular-bundle/)
- [Interatrial septum](https://durgical.com/en/anatomy/interatrial-septum/)
- [Coronary sinus](https://durgical.com/en/anatomy/coronary-sinus/)

## Why it happens

- [How arrhythmias arise](https://durgical.com/en/physiology/how-arrhythmias-arise/)
- [The cardiac conduction system](https://durgical.com/en/physiology/the-cardiac-conduction-system/)
- [Refractory periods and excitability](https://durgical.com/en/physiology/refractory-periods-and-excitability/)

## What it is

A group of paroxysmal, regular, narrow-complex tachycardias that use the AV node or tissue above it. The two main re-entrant types are AV nodal re-entrant tachycardia (AVNRT) and AV re-entrant tachycardia (AVRT) over an accessory pathway.

## Who gets it

A common arrhythmia in young and otherwise healthy people. AVNRT is the most frequent type and is more common in women; AVRT is more common in younger people and is the typical mechanism in Wolff-Parkinson-White syndrome.

## Causes

- AVNRT: dual pathways (fast and slow) within or near the AV node
- AVRT: an accessory pathway connecting atrium and ventricle (Wolff-Parkinson-White when it conducts forward in sinus rhythm)
- Triggers: premature beats, caffeine, alcohol, stimulants, stress, hyperthyroidism

## Risk factors

- Female sex (AVNRT)
- Pre-excitation on the ECG (accessory pathway)
- Stimulants, sleep deprivation and hyperthyroidism
- Congenital heart disease such as Ebstein anomaly (AVRT)

## Pathophysiology

A premature beat finds one pathway refractory and travels down the other, then returns up the first, creating a self-sustaining re-entry circuit. In AVNRT the circuit lies around the AV node; in AVRT it uses the node one way and the accessory pathway the other. Because the AV node is part of both circuits, slowing AV nodal conduction (vagal manoeuvres, adenosine) usually terminates them.

## Classification

- AV nodal re-entrant tachycardia (AVNRT), the most common
- AV re-entrant tachycardia (AVRT): orthodromic (narrow QRS) or antidromic (wide QRS)
- Focal atrial tachycardia (less common)

## Symptoms and signs

- Sudden-onset and sudden-ending rapid palpitations
- Pounding sensation in the neck
- Dizziness, dyspnoea or [chest](https://durgical.com/en/anatomy/region/chest/) discomfort
- Polyuria after an episode
- Syncope (uncommon)

## Red flags

- Hypotension, syncope, chest pain or heart failure during the tachycardia
- Wide-complex tachycardia (consider VT or pre-excitation)
- Pre-excited atrial fibrillation in Wolff-Parkinson-White (irregular, very fast, wide QRS)
- Family history of sudden death

## Diagnosis

**Clinical**
Abrupt-onset regular tachycardia, often in a young person; check stability, and note that vagal manoeuvres can end it.

**Tests**
12-lead ECG during the episode: regular narrow QRS, usually 150–250 per minute, with P waves hidden or just after the QRS. Baseline ECG in sinus rhythm for pre-excitation (short PR, delta wave). Thyroid function and electrolytes; Holter or event recorder for infrequent episodes; electrophysiological study before ablation.

**Imaging**
Echocardiography to exclude structural heart disease.

## Differential diagnosis

- Sinus tachycardia
- Atrial flutter with 2:1 conduction
- Atrial fibrillation (irregular)
- Ventricular tachycardia when the QRS is wide
- Panic attack

## Goal of treatment

End the episode safely, prevent recurrences when they are frequent or troublesome, and identify accessory pathways at risk of sudden death.

## Treatment

**Acute**
Stable patient: vagal manoeuvres first (modified Valsalva, carotid sinus massage when safe).

**Acute**
If vagal manoeuvres fail: rapid intravenous adenosine with continuous ECG recording; then intravenous nondihydropyridine calcium-channel blockers or beta-blockers.

**Acute**
Unstable patient: synchronised electrical cardioversion.

**Acute**
Pre-excited atrial fibrillation: AV nodal blockers (adenosine, calcium-channel blockers, beta-blockers, digoxin) are avoided; procainamide or cardioversion is used.

**Procedure**
Catheter ablation of the slow pathway or accessory pathway is curative in most patients and is first-line for recurrent SVT and symptomatic Wolff-Parkinson-White.

**Medical**
Long-term beta-blockers or calcium-channel blockers when ablation is not chosen.

## Complications

- Syncope and injury
- Tachycardia-induced cardiomyopathy when episodes are prolonged or incessant
- Sudden death from pre-excited atrial fibrillation in Wolff-Parkinson-White (rare)
- Reduced quality of life from recurrent episodes

## Prognosis

Generally excellent. Most patients have a structurally normal heart, and catheter ablation cures AVNRT and AVRT in the large majority.

## Prevention

- Avoiding personal triggers (stimulants, excess caffeine or alcohol)
- Ablation of high-risk accessory pathways

## Test yourself

Think of the answer, then tap the question to see it.

## What is the most common type of paroxysmal supraventricular tachycardia?

AV nodal re-entrant tachycardia (AVNRT).

## What is the first step in a haemodynamically stable patient with SVT?

Vagal manoeuvres, such as the modified Valsalva manoeuvre.

## Which drug is given if vagal manoeuvres fail, and how?

Adenosine as a rapid intravenous push followed by a flush, with continuous ECG recording.

## What are the ECG features of Wolff-Parkinson-White pre-excitation in sinus rhythm?

Short PR interval, a delta wave (slurred QRS upstroke) and a widened QRS.

## Which drugs are avoided in pre-excited atrial fibrillation?

AV nodal blockers (adenosine, calcium-channel blockers, beta-blockers, digoxin), because they can speed conduction down the accessory pathway.

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## Related conditions

- [Atrial fibrillation](https://durgical.com/en/conditions/atrial-fibrillation/)
- [Ventricular tachycardia](https://durgical.com/en/conditions/ventricular-tachycardia/)
- [Graves disease (hyperthyroidism)](https://durgical.com/en/conditions/graves-disease/)
- [Atrioventricular (heart) block](https://durgical.com/en/conditions/atrioventricular-block/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Paroxysmal supraventricular tachycardia (PSVT): MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000183.htm) (MedlinePlus, US National Library of Medicine, 2026).

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Source: https://durgical.com/en/conditions/supraventricular-tachycardia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/supraventricular-tachycardia/