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Health condition · Clinically reviewed

Supraventricular tachycardia (SVT), fast regular palpitations — usually curable.

Sudden-onset fast, regular palpitations from an electrical circuit above the ventricles. Vagal manoeuvres often terminate; catheter ablation cures most.

Jump to treatment See red-flag symptoms

Reviewed by Dr A. Hassan, MRCP, FRCR · Updated 2026-07-30 · 7 min read · Next review 2027-07-30

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why this guide is different

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Every claim is checked against ESC, NICE CKS, or a peer-reviewed source you can see at the end.

  • 03

    Current for 2026

    Reflects current UK and European guidance on acute termination and catheter ablation.

Key facts

What SVT is, in one screen.

The six things worth knowing before anything else — the mechanism, how to stop an episode, and the option that cures it.

What it is
A regular tachycardia driven by an electrical circuit above the ventricles — either in the atria or the AV junction.
Main types
AVNRT (most common), AVRT (including Wolff–Parkinson–White), and atrial tachycardia.
Pattern
A sudden-on / sudden-off rhythm — episodes start and stop abruptly, often at rest.
First-line manoeuvre
Vagal manoeuvres (the modified Valsalva with leg raise) terminate around 40% of episodes.
Acute drug
Adenosine, given as a rapid IV push in hospital, terminates most SVTs within seconds.
Definitive fix
Catheter ablation cures more than 90% of AVNRT and typical AVRT cases in a single day-case procedure.

Why this guide matters

SVT is one of the few arrhythmias you can cure.

Three things worth reading before you decide anything about your rhythm.

  • It’s almost always curable

    Unlike most arrhythmias, SVT can usually be permanently fixed with a single ablation procedure.

  • You can learn to stop episodes

    The modified Valsalva manoeuvre — taught in one visit — works nearly half the time at home.

  • Watch for the WPW subgroup

    Pre-excitation on a baseline ECG changes the risk profile and the choice of drugs.

Diagnosis

How SVT is confirmed — in the order it usually happens.

From the first episode to a definitive plan — a typical UK-aligned pathway.

  1. 01

    First contact

    History points the way

    Sudden-onset regular palpitations that stop as abruptly as they start are highly suggestive of SVT.

  2. 02

    First contact

    An ECG during an episode

    Capturing the rhythm on a 12-lead is the single most useful diagnostic step.

  3. 03

    First contact

    Holter, event or smartwatch

    For intermittent episodes, ambulatory monitoring or a smartwatch tracing often catches the arrhythmia.

  4. 04

    Further checks

    Implantable loop recorder

    Considered when episodes are rare but disruptive and non-invasive monitors have not captured them.

  5. 05

    Further checks

    Cardiology and electrophysiology

    Referral for expert review, mechanism classification and discussion of longer-term options.

  6. 06

    Further checks

    Echocardiogram

    Excludes structural heart disease before deciding on antiarrhythmic drug choice.

  7. 07

    Next steps

    Discuss catheter ablation

    A day-case electrophysiology study and ablation offers a curative option for most SVT subtypes.

Symptoms

What SVT actually feels like.

The commonest symptoms and the ones that mean stop and get help. Sudden-on / sudden-off is the classic clue.

  • Sudden fast palpitations

    A regular racing heartbeat that begins abruptly, often at rest or with a trigger.

  • Sudden termination

    The episode stops as suddenly as it started — sometimes on its own, sometimes with a manoeuvre.

  • Dizziness

    Light-headedness during the episode as the very fast rate reduces cardiac output.

  • Breathlessness during episode

    Feeling short of breath while the heart is racing, easing when the rhythm returns to normal.

  • Chest discomfort

    A tight or heavy feeling in the chest during an episode, without lasting pain.

  • Anxiety trigger

    Adrenaline surges, stress and stimulants can precipitate an episode.

  • Exercise-triggered

    Some SVTs start during exertion, especially with a sudden change of pace.

  • Red flag: syncope with SVT

    Blacking out during an episode is not typical — arrange urgent cardiology review.

Treatment

The main options, and what each is for.

Modern SVT care is a stepped approach — stop the episode, prevent recurrence, and offer a curative ablation when it matters.

  • Modified Valsalva (leg-raise)

    The evidence-based vagal manoeuvre — blow into a syringe for 15 seconds, then lie flat with legs raised.

  • Adenosine in acute setting

    A rapid IV push given in hospital that briefly blocks the AV node and terminates most SVTs.

  • Beta-blocker (bisoprolol)

    A common daily preventer that reduces episode frequency and slows the heart during one.

  • Non-dihydropyridine CCB

    Diltiazem or verapamil are alternatives when a beta-blocker is unsuitable.

  • Flecainide

    Considered in a structurally normal heart when other options are not tolerated or effective.

  • Catheter ablation

    A day-case procedure that maps and treats the SVT circuit — curative in over 90% of cases.

  • Pill-in-pocket approach

    A single dose of medication taken only when an episode occurs, for suitable patients.

  • Avoid catecholamines / stimulants

    Reducing caffeine, decongestants and recreational stimulants can lower episode frequency.

Red flags

When SVT becomes an emergency.

These are the situations to act on immediately — call 999 or 111, or head to A&E.

  • Syncope with SVT

    Losing consciousness during an episode is unusual — needs urgent cardiology review.

  • Chest pain with SVT

    New chest pain during an episode should be assessed in an emergency department.

  • Structural heart disease with SVT

    SVT on top of an abnormal heart changes drug choice — specialist review is needed.

  • Pregnancy

    Any new arrhythmia in pregnancy should be reviewed promptly — some drugs are avoided.

  • WPW with pre-excited AF

    A very fast, irregular, broad-complex rhythm on a WPW background is a 999 emergency.

  • Post-ablation complications

    New chest pain, breathlessness, fever or leg swelling after ablation needs urgent review.

  • Recurrent syncope

    Repeated blackouts — with or without palpitations — warrant same-day assessment.

  • Sudden cardiac death family history

    A first-degree relative with sudden cardiac death changes how palpitations are investigated.

  • Antiarrhythmic pro-arrhythmia

    New or worsening palpitations after starting an antiarrhythmic drug needs prompt review.

Living with it

The everyday things that change SVT — a lot.

Four levers that, together, reduce how often SVT interrupts your day.

  • Manoeuvre skill

    Practise the modified Valsalva

    Learning the leg-raise technique means you can often terminate an episode at home before it becomes disruptive.

  • Triggers

    Notice your patterns

    Caffeine, alcohol, poor sleep and stimulants trigger episodes in many people — track what precedes them.

  • Recording

    Capture an episode

    A single-lead smartwatch tracing during an episode helps your cardiologist confirm the mechanism.

  • Ablation planning

    Consider it early

    For frequent or disruptive SVT, ablation is usually more effective than long-term daily medication.

Frequently asked

Everything we get asked about SVT.

Quick answers on manoeuvres, medications, ablation, and what to do when episodes strike.

  • What is supraventricular tachycardia?

    A fast, regular heart rhythm driven by an electrical circuit above the ventricles. It typically starts and stops suddenly and is one of the most treatable arrhythmias.

  • How is SVT diagnosed?

    An ECG captured during an episode is the gold standard. Between episodes, a Holter monitor, event recorder, smartwatch tracing or implantable loop recorder is used to catch the rhythm.

  • What is the modified Valsalva manoeuvre?

    You blow into a 10ml syringe for 15 seconds while sitting up, then immediately lie flat while an assistant raises your legs. It terminates around 40% of SVT episodes in trials.

  • Do I need medication for SVT?

    Not always. Some people manage with vagal manoeuvres and lifestyle changes. Daily beta-blockers, calcium-channel blockers or a pill-in-pocket approach are options for more frequent episodes.

  • What does catheter ablation involve?

    A day-case procedure where an electrophysiologist maps the SVT circuit and treats the offending tissue with heat or cold. Success rates exceed 90% for AVNRT and typical AVRT.

  • Is SVT dangerous?

    For most people SVT is disruptive rather than dangerous. The exception is Wolff–Parkinson–White syndrome with pre-excited atrial fibrillation, which is a true emergency.

What this guide is based on

Sources reviewed for this page.

  • European Society of Cardiology. Guidelines for the management of patients with supraventricular tachycardia.
  • NICE CKS. Palpitations: assessment and management.
  • British Heart Rhythm Society. Position statements on SVT and catheter ablation.
  • Arrhythmia Alliance. Patient information on SVT and vagal manoeuvres.

Reviewed by Dr A. Hassan, MRCP, FRCR. Next scheduled review 2027-07-30.

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