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Health condition · Clinically reviewed

AVNRT, the commonest paroxysmal SVT, and how a day case ablation cures it.

Sudden fast palpitations that stop as abruptly as they start. Usually benign, always treatable, and often curable in a single afternoon.

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Why trust this guide

  • 01

    Clinically reviewed

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

  • 02

    Sourced from guidance

    Checked against ESC, NICE and peer-reviewed cardiology sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including slow pathway ablation, cryoablation and the modified Valsalva.

Key facts

AVNRT at a glance.

The essentials, in plain English. What the rhythm is, who it affects and how it is treated in the UK today.

  • What it is

    A reentrant tachycardia inside the compact AV node using dual fast and slow pathways. The commonest paroxysmal supraventricular tachycardia in the UK.

  • Who it affects

    Any age but classically young women, with a female to male ratio of about 2 to 1. Usually a structurally normal heart.

  • How it feels

    Sudden regular pounding palpitations at 150 to 250 beats per minute, often with neck pounding, breathlessness and a passing wobble.

  • Prognosis

    Benign in almost everyone. Episodes are disruptive rather than dangerous, though rarely presyncope or syncope occur.

  • Acute fix

    Vagal manoeuvres first, then intravenous adenosine. DC cardioversion only if the patient is haemodynamically unstable.

  • Curative option

    Catheter ablation of the slow pathway is first line for recurrent symptomatic AVNRT, with success rates above 95 per cent.

Why this guide matters

A rhythm problem with a very good ending.

AVNRT is disruptive but usually benign, and a well planned ablation is one of the most rewarding cures in cardiology.

  • The circuit sits inside the AV node

    Dual pathways, one fast and one slow, create a self sustaining loop. Understanding this explains almost everything about the rhythm.

  • Vagal manoeuvres often work

    The modified Valsalva with a supine leg raise breaks a good share of episodes without a drop of medication.

  • Ablation is often curative

    Slow pathway modification stops the rhythm returning in more than 95 per cent of patients, with an AV block risk well under 1 per cent.

How the diagnosis is made

From first palpitations to a clear plan.

The steps a UK GP, emergency clinician or cardiologist will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Story and pulse check

    Sudden on, sudden off palpitations at a regular fast rate are the classic clue. Neck pounding and polyuria after an episode point strongly to AVNRT.

  2. 02

    Assessing

    12-lead ECG in sinus rhythm

    Usually completely normal between attacks. This does not rule AVNRT out.

  3. 03

    Assessing

    12-lead ECG during tachycardia

    The prize catch. Narrow QRS at 150 to 250 bpm with a pseudo r prime in V1 and a pseudo S wave in the inferior leads suggests typical slow-fast AVNRT.

  4. 04

    Confirming

    Ambulatory monitoring

    A 24 to 72 hour Holter, an event recorder or occasionally an implantable loop recorder captures short or infrequent episodes.

  5. 05

    Confirming

    Echocardiogram

    A transthoracic echo confirms a structurally normal heart and rules out other drivers of tachycardia.

  6. 06

    Confirming

    Bloods and observations

    Thyroid function, electrolytes and a haemoglobin check exclude common tachycardia mimics and triggers.

  7. 07

    Preparing

    Electrophysiology study

    The definitive test. Programmed stimulation confirms dual AV nodal physiology and reproduces the circuit before ablation.

Typical timeline: from first captured ECG to curative ablation in a matter of weeks in most UK centres.

Symptoms

What an AVNRT episode actually feels like.

The classic mix of sudden fast palpitations, neck pounding and a rush of urine afterwards. And the features that mean it is time to call for help.

  • Sudden regular palpitations

    Fast, forceful and unmistakable. Rates typically sit between 150 and 250 beats per minute with an abrupt on and off.

  • Neck pounding (frog sign)

    Cannon A waves in the neck as the atria contract against a closed tricuspid valve. A near diagnostic feature.

  • Polyuria after an episode

    Atrial stretch releases atrial natriuretic peptide, which drives a burst of urine output soon after the tachycardia stops.

  • Chest discomfort

    Tightness or pressure rather than the crushing pain of an infarct. Rate related and usually settles as the rhythm settles.

  • Breathlessness

    A rapid rate shortens diastolic filling. Many people feel puffed or unable to hold a full breath during an episode.

  • Presyncope and lightheadedness

    A brief drop in cardiac output can cause a grey out. Frank blackout is uncommon but does happen.

  • Anxiety and shakiness

    A surge of adrenaline rides alongside the arrhythmia. The distress is real, not imagined, and passes with the rhythm.

  • Red flag - collapse or chest pain

    Syncope, ongoing chest pain or signs of shock during an episode warrant an emergency 999 call and a cardiology review.

Treatment

How AVNRT is treated in the UK.

A stepped ladder that starts with a vagal manoeuvre, moves through targeted drugs and often ends with a single day case ablation.

  • Vagal manoeuvres

    Standard Valsalva and the modified REVERT technique with a supine leg raise. Simple, safe and effective in a good proportion of episodes.

  • Intravenous adenosine

    First line drug for acute termination. Given as a rapid 6 mg bolus, escalating to 12 mg if needed. Brief, uncomfortable and usually decisive.

  • IV verapamil or diltiazem

    A calcium channel blocker option when adenosine is contraindicated or ineffective, provided blood pressure and left ventricular function are preserved.

  • Synchronised DC cardioversion

    Reserved for a patient who is haemodynamically unstable. Rare in AVNRT because most episodes are well tolerated.

  • Beta blocker maintenance

    A daily beta blocker such as bisoprolol reduces frequency for patients who prefer medication or are waiting for a procedure.

  • Diltiazem or verapamil daily

    An alternative long term rate control option, particularly when a beta blocker is not tolerated.

  • Flecainide (selected patients)

    A pill in the pocket or daily option for structurally normal hearts, prescribed by a cardiologist after appropriate assessment.

  • Slow pathway catheter ablation

    First line for symptomatic recurrent AVNRT. A day case procedure with success above 95 per cent and an AV block risk under 1 per cent.

What this guide is based on

The sources behind every claim on this page.

UK and European cardiology guidance and trial evidence, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or cardiologist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • European Society of Cardiology (ESC). Guidelines for the management of patients with supraventricular tachycardia.

  • NICE Clinical Knowledge Summary. Supraventricular tachycardia.

  • REVERT trial. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias. The Lancet.

  • British Heart Rhythm Society. Standards for catheter ablation of supraventricular tachycardia.

Red flags

When palpitations need urgent attention.

Most AVNRT is manageable and safe. These are the situations that are not, and where you need to be seen quickly.

  • Syncope during an episode

    A frank blackout is uncommon in AVNRT and warrants urgent cardiology review to exclude a more sinister arrhythmia.

  • Ongoing chest pain

    Rate related tightness usually settles as the rhythm settles. Persistent pain needs an emergency assessment to rule out ischaemia.

  • Signs of shock

    Cold, clammy, confused or a very low blood pressure during a tachycardia is a 999 call. This means synchronised cardioversion, not more tablets.

  • Very fast wide complex rhythm

    A broad complex tachycardia is ventricular tachycardia until proven otherwise. Treat it as such and get help fast.

  • New heart failure symptoms

    Frequent long episodes can cause tachycardia mediated cardiomyopathy. Breathlessness, ankle swelling or reduced exercise tolerance need review.

  • Pregnancy with recurrent SVT

    AVNRT can worsen in pregnancy. A joint obstetric and cardiology plan for safe termination and prevention is essential.

  • Structural heart disease

    A new murmur, abnormal ECG or previous cardiac history changes the differential and the drug options. Do not manage in isolation.

  • Stimulant related episodes

    Recreational stimulants, high dose caffeine or unregulated pre workouts can drive frequent SVT. A frank conversation matters.

  • Post ablation warning signs

    Chest pain, breathlessness, groin swelling or fainting after ablation should trigger a same day call to the electrophysiology team.

Living with it

A treatable rhythm, with a clear ladder.

Four things that make the biggest difference day to day. Knowing your triggers, practising a good vagal manoeuvre, considering ablation early and looking after the mental load.

A quiet reminder

Curable does not have to mean scary.

For most people AVNRT is a nuisance that a single day case procedure can put behind them. It is reasonable to ask about it early.

  1. 01 Triggers

    Know your provocations

    Caffeine, alcohol, poor sleep, dehydration and stress top the list. A simple diary quickly reveals your personal pattern.

  2. 02 Manoeuvre

    Practise the modified Valsalva

    Rehearsing it while well means you can use it confidently during an episode. The supine leg raise really does add to the effect.

  3. 03 Escalate

    Consider ablation early

    A curative day case procedure often beats years of daily tablets. Ask for a referral if episodes are frequent, long or frightening.

  4. 04 Support

    Talk about the mental load

    Waiting for the next episode is exhausting. Cardiac psychology, patient groups and a clear plan reduce the background anxiety.

Frequently asked

Everything we get asked about AVNRT.

Quick answers on vagal manoeuvres, adenosine, daily tablets and catheter ablation.

  • What is AVNRT?

    AVNRT stands for atrioventricular nodal reentrant tachycardia. It is a fast, regular rhythm caused by a reentrant circuit inside the compact AV node, which contains two functionally distinct pathways, a fast pathway and a slow pathway. In the common slow-fast form, the impulse travels down the slow pathway and back up the fast pathway, producing rates of 150 to 250 beats per minute. It is the commonest paroxysmal supraventricular tachycardia and usually occurs in structurally normal hearts.

  • How do I know it is AVNRT and not something else?

    The story alone is a strong clue. Sudden on and sudden off palpitations at a regular fast rate, often with neck pounding and a rush of urine afterwards, fit the pattern well. A 12-lead ECG captured during an episode is the key investigation, showing a narrow QRS regular tachycardia with a pseudo r prime in V1 and a pseudo S wave in the inferior leads for the typical form. An electrophysiology study confirms dual AV nodal physiology definitively.

  • Is AVNRT dangerous?

    For the vast majority of people it is benign. It is disruptive rather than life threatening, and long term prognosis in a structurally normal heart is excellent. Syncope is rare, and sudden cardiac death is not a feature of AVNRT itself. That said, ongoing chest pain, blackout during an episode or signs of shock always deserve urgent assessment.

  • What should I do during an episode?

    Sit or lie down safely. Try a vagal manoeuvre such as the modified Valsalva, which involves a strong forced exhale against a closed airway for 15 seconds while sitting, followed by a rapid lie down and passive leg raise. If the rhythm does not stop within a few minutes, or if you feel unwell, dial 999. Do not drive yourself to hospital during an ongoing tachycardia.

  • Do I need daily medication?

    Not always. Many people manage with vagal manoeuvres alone. Daily beta blockers, diltiazem, verapamil or flecainide are options for frequent or disabling episodes, or as a bridge to a procedure. The choice depends on your other health conditions and preferences and is best discussed with a cardiologist.

  • What does slow pathway ablation involve?

    It is a day case catheter procedure carried out under local anaesthetic and sedation in an electrophysiology laboratory. Fine catheters are passed via the femoral vein to the right atrium, the slow pathway is mapped and then modified using radiofrequency energy or cryoablation. Success rates are above 95 per cent, the risk of needing a pacemaker due to AV block is under 1 per cent, and most people are home the same day and back to normal activity within a week.

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