Supraventricular tachycardia (SVT)Overview

Supraventricular tachycardia (SVT) is a condition where your heart suddenly beats much faster than normal. It's not usually serious, but some people may need treatment.

What is SVT?

SVT happens when the electrical system that controls your heart rhythm isn't working properly.

This causes your heart to suddenly beat much faster. It can then slow down abruptly.

A normal resting heart rate is 60 to 100 beats per minute (bpm). But with SVT your heart rate suddenly goes above 100bpm. This can happen when you're resting or doing exercise.

Symptoms of SVT

Having SVT means your heart suddenly beats faster. This:

• usually lasts for a few minutes, but can sometimes last for several hours
• can happen several times a day or once a year – it varies
• can be triggered by tiredness, caffeine, alcohol or drugs – but often there's no obvious trigger
• can happen at any age, but often starts for the first time in children and young adults – many people have their first symptoms between 25 and 40

You may get no other symptoms, but sometimes people also:

• have chest pain
• feel weak, breathless or lightheaded
• feel tired
• feel sick or are sick

See a GP if you keep getting a fast heartbeat

It's important to get it checked out – you might need a test, such as an electrocardiogram (ECG), to find out what's going on.

Call 999 or go to A&E if:

• you have been diagnosed with SVT and your episode has lasted longer than 30 minutes
• you have sudden shortness of breath with chest pain

You need to go to hospital for treatment immediately.

Things you can do to help

If your episodes of SVT only last a few minutes and don't bother you, you won't need treatment.

But if your episodes last longer or make you feel unwell, there are things you can do to help.

How to stop an episode

These techniques aim to help stop your SVT episode when it comes on:

• the valsalva manoeuvre – take a deep breath, shut your mouth tight, hold your nose tightly and blow out as hard as you can
• the cold water technique – fill a bowl with cold water and put some ice in it, hold your breath and put your face in the water for a few seconds

Lifestyle changes

You can also make changes to your lifestyle to reduce your chances of having further episodes, such as:

• cutting down on the amount of caffeine or alcohol you drink
• stopping or cutting back on smoking
• making sure you get enough rest

Treating SVT in hospital

SVT is rarely life threatening. But you may need treatment in hospital if you keep having long episodes.

This may include:

• medicines to control the episodes of SVT – given as tablets or through a vein
• cardioversion – a small electric shock to the heart to help it get back to a normal rhythm
• catheter ablation – a treatment where thin tubes are placed through a vein or artery into your heart to correct the problem with the electrical system; this permanently cures the problem in most patients

Find out more about cardioversion and more about catheter ablation from the British Heart Foundation.