---
title: Supraventricular tachycardia
description: What supraventricular tachycardia is, why its episodes happen, how they are recognised, which treatment approaches clinical guidelines describe and when urgent help is needed.
type: disease
preset: supraventricular-tachycardia
aliases:
  - SVT
  - paroxysmal supraventricular tachycardia
  - PSVT
  - AVNRT
  - AVRT
sources:
  - tier: guideline
    org: minzdrav-rf
    title: Наджелудочковые тахикардии
    year: 2025
    doi: 10.15829/1560-4071-2025-6448
    url: https://cr.minzdrav.gov.ru/view-cr/619_3
  - tier: guideline
    org: esc
    title: 2019 Рекомендации ESC по лечению пациентов с наджелудочковыми тахикардиями
    year: 2020
    doi: 10.15829/1560-4071-2020-3864
    url: https://doi.org/10.15829/1560-4071-2020-3864
  - tier: reference
    org: msd-manuals
    title: Reentrant (Paroxysmal) Supraventricular Tachycardias (PSVT)
    year: 2024
    url: https://www.msdmanuals.com/professional/cardiovascular-disorders/specific-cardiac-arrhythmias/reentrant-paroxysmal-supraventricular-tachycardias-psvt
sources_checked: 2026-10-12
review: null
---

Supraventricular tachycardia (SVT) is a fast heart rhythm, over 100 beats per minute at rest, that starts in the bundle of His or above it.<Cite n={[1, 2]} /> This article is about paroxysmal SVT, in which the impulse travels round a closed circuit (the re-entry mechanism): episodes start suddenly and stop suddenly, and the rhythm is fast — 120 to 250 beats per minute — and regular.<Cite n={3} /> In the general population SVT affects about 2.25 people in 1,000, and the risk in women is twice that in men.<Cite n={2} />

<Diagram name="supraventricular-tachycardia">
  <p slot="normal">
    Normally the impulse from the <Structure id="sa-node">sinus node</Structure> travels across the atria to the <Structure id="av-node">atrioventricular (AV)
    node</Structure>, and from there along the <Structure id="bundle-of-his">bundle of His</Structure> and its branches (the His–Purkinje system) to the
    ventricles.<Cite n={[1, 3]} />
  </p>
  <p slot="disease">
    In the most common form, AV nodal re-entrant tachycardia (AVNRT), the AV node has two conduction
    pathways: a "fast" one and a "slow" one.<Cite n={1} /> An early impulse (an atrial premature
    beat) finds the fast pathway not yet ready to conduct, goes down the slow pathway, returns up the
    fast one, and the circuit closes.<Cite n={[1, 3]} /> The impulse keeps going round, activating
    the ventricles on every lap, so the ECG shows a fast, regular tachycardia.<Cite n={[1, 3]} />
  </p>
</Diagram>

## Why it happens

<Patient>

The most common form, about half of all cases, is AV nodal re-entrant tachycardia (AVNRT).<Cite n={1} /> In AVNRT the AV node — the junction through which the impulse normally passes from the atria to the ventricles — has two conduction pathways, and the impulse can start circling between them.<Cite n={1} /> The circuit is most often set off by a single extra beat of the atria (an atrial premature beat).<Cite n={[1, 3]} /> AVNRT is more common in women and is usually not linked to heart disease.<Cite n={1} />

About another quarter of cases involve an extra (accessory) conduction pathway between an atrium and a ventricle; such a pathway usually forms before birth.<Cite n={1} /> The impulse then circles through the AV node and this accessory pathway, and episodes usually begin at a younger age.<Cite n={1} /> An accessory pathway is the basis of [Wolff-Parkinson-White (WPW) syndrome](../wpw-syndrome/).<Cite n={3} />

AVNRT episodes can be triggered by physical exertion, emotional stress, digestive upset or alcohol.<Cite n={1} /> Sometimes SVT is a complication of another condition, such as hypertension or coronary heart disease, and then treating that condition is the basis of treatment.<Cite n={1} />

</Patient>

<Student>

AVNRT is caused by re-entry within the AV node, where the compact AV junction contains zones of "fast" conduction (with a longer effective refractory period) and "slow" conduction (with a shorter one).<Cite n={1} /> Initiation requires an atrial premature beat with a critical coupling interval at which the fast pathway is refractory and the slow pathway is not.<Cite n={1} /> While the impulse travels down the slow pathway, the fast pathway recovers and conducts retrogradely, closing the circuit of typical ("slow-fast") AVNRT.<Cite n={[1, 3]} />

Atrioventricular re-entrant tachycardia (AVRT) is re-entry involving the AV junction and His–Purkinje system on one side and an accessory atrioventricular pathway on the other; accessory pathways usually result from abnormal fetal development of the fibrous rings (annuli) of the mitral and/or tricuspid valves.<Cite n={1} /> The usual form is orthodromic AVRT: activation passes through the AV node and His–Purkinje system to the ventricles and returns to the atria via the accessory pathway.<Cite n={3} />

WPW syndrome comprises a PR interval shorter than 120 ms, QRS wider than 120 ms, a delta wave at the start of the R wave and recurrent SVT; pre-excitation without SVT is called the WPW ECG pattern (phenomenon).<Cite n={1} /> The life-threatening arrhythmia in manifest WPW syndrome is atrial fibrillation or flutter: if the accessory pathway has a short antegrade refractory period, rapid conduction to the ventricles can lead to ventricular fibrillation.<Cite n={[1, 2]} />

</Student>

<HeartModel highlight={['av-node', 'bundle-of-his']} />

## Symptoms

<Patient>

The main sign is an episode of fast, regular palpitations that starts suddenly and stops just as suddenly.<Cite n={[1, 3]} /> An episode can last from a few seconds to several hours.<Cite n={3} />

During an episode there may be chest discomfort or tightness, breathlessness, dizziness and passing large amounts of urine; less often sweating, and sometimes feeling faint or even losing consciousness.<Cite n={1} /> Some people feel pulsation in the neck.<Cite n={1} /> Fainting is rare, but dizziness is common.<Cite n={1} /> The tachycardia can also cause no symptoms at all.<Cite n={1} />

</Patient>

<Student>

Patients with AVNRT often describe a sensation of "shirt flapping" or "neck pounding"; syncope is rare, while dizziness is common.<Cite n={1} />

AVNRT is more common in women, with a mean age at onset of 32 years, and is usually not associated with structural heart disease.<Cite n={1} /> In AVRT the mean age at symptom onset is 23 years.<Cite n={1} /> In patients with structural heart disease AVNRT may cause acute left ventricular failure, and in rare cases of persistent tachycardia, arrhythmia-induced cardiomyopathy.<Cite n={1} />

</Student>

## How it is diagnosed

<Patient>

The main test is an ECG.<Cite n={1} /> It is best if the ECG is recorded during an episode, so guidelines advise calling an ambulance during episodes.<Cite n={2} /> If episodes are rare, the doctor may arrange longer rhythm recording: 24-hour or multi-day Holter monitoring, or a wearable or implantable recorder.<Cite n={1} /> A heart ultrasound (echocardiogram) shows whether the structure of the heart has changed.<Cite n={1} />

</Patient>

<Student>

The ECG is the main diagnostic test; the ideal tool is an ECG recorded during an episode.<Cite n={[1, 2]} />

Narrow QRS complexes (≤120 ms) result from rapid ventricular activation via the His–Purkinje system and indicate that the arrhythmia originates above or within the bundle of His.<Cite n={1} /> In typical AVNRT retrograde P′ waves usually merge with the QRS complex or are seen at its end (often as a pseudo-R′ deflection in lead V1).<Cite n={[1, 3]} /> In orthodromic AVRT the heart rate is usually 150–250 per minute, the RP′ interval is shorter than P′R, and the QRS is of normal duration without pre-excitation.<Cite n={1} />

A wide-complex tachycardia not known to be supraventricular in origin must be treated acutely as ventricular tachycardia.<Cite n={3} />

</Student>

## How it is treated

<Patient>

Many episodes stop on their own before treatment.<Cite n={3} /> If an episode continues and the person is stable, doctors first use vagal manoeuvres, such as the Valsalva manoeuvre: they can stop the episode and also help clarify the diagnosis.<Cite n={[1, 2]} /> For people whose diagnosis is already confirmed, the doctor can explain which manoeuvres they may use during an episode.<Cite n={[1, 3]} />

If vagal manoeuvres do not work, the doctor gives antiarrhythmic medicines into a vein.<Cite n={1} /> If the person is unstable or the medicines do not work, the rhythm is restored with an electric shock — electrical cardioversion.<Cite n={[1, 2]} />

To get rid of frequent or troublesome episodes, catheter ablation works best: a catheter is passed through a blood vessel to the heart and used to treat the precise area where the circuit closes; it usually cures the tachycardia.<Cite n={[1, 3]} /> If ablation is unwanted or not possible, the doctor may prescribe medicines to prevent episodes.<Cite n={1} /> In AVNRT with rare, short episodes and mild symptoms, treatment may not be needed: in about half of these people symptoms go away within 13 years.<Cite n={1} /> The doctor and patient decide together which approach to take.

</Patient>

<Student>

For narrow-QRS SVT of unknown mechanism, synchronised electrical cardioversion is recommended in haemodynamically unstable patients and vagal manoeuvres in stable patients.<Cite n={[1, 2]} /> If vagal manoeuvres fail in stable patients, intravenous antiarrhythmic drugs are recommended, and if these fail, synchronised cardioversion.<Cite n={1} /> AV nodal blockers are used when the QRS is narrow and regular: blocking AV nodal conduction for one beat interrupts the re-entrant cycle.<Cite n={3} /> In pre-excited atrial fibrillation, drugs acting on the AV node must be avoided because they can increase the risk of ventricular fibrillation.<Cite n={1} />

Catheter ablation is the treatment of choice for SVT in general and for symptomatic patients with AVNRT; it is recommended for symptomatic recurrent AVNRT.<Cite n={1} /> Slow-pathway modification is effective in both typical and atypical AVNRT: success rate 97%, recurrence risk 1.3–4%, risk of AV block below 1%.<Cite n={[1, 2]} /> Ablation of the accessory pathway is recommended for all patients with symptomatic recurrent AVRT.<Cite n={1} />

To prevent AVNRT episodes when ablation is unwanted or not feasible, beta-blockers are recommended, and, in patients who do not have heart failure with reduced left ventricular ejection fraction, also non-dihydropyridine calcium channel blockers.<Cite n={1} /> Treatment is not recommended for minimally symptomatic patients with AVNRT who have very rare and short episodes.<Cite n={1} />

</Student>

## When to call an ambulance

Call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) if an episode of palpitations comes with fainting, feeling faint (sudden darkening of vision, weakness, dizziness, cold sweat) or a drop in blood pressure (the upper, systolic, reading below 100 mm Hg).<Cite n={1} /> Guidelines also name chest pain and a suspected heart attack as signs of an unstable condition that requires hospital admission — call an ambulance in these cases too.<Cite n={1} />

If an episode does not stop, call an ambulance as well: guidelines advise calling an ambulance team during episodes, and people whose episode was not stopped by emergency care before hospital are sent to hospital urgently.<Cite n={[1, 2]} />

<Quiz />