Supraventricular tachycardia (SVT) happens when the electrical system that controls your heart rhythm is not 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.

Having supraventricular tachycardia (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 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 years old

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

• have chest pain or discomfort
• feel weak, breathless, lightheaded or dizzy
• feel tired

See a GP if:

Call 999 if:

If your episodes of supraventricular tachycardia (SVT) only last a few minutes and do not bother you, you may not need treatment.

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

• cutting down on the amount of caffeine or alcohol you drink
• stopping or cutting back on smoking

Your doctor may also be able to recommend some simple techniques to help stop episodes when they happen.

Supraventricular tachycardia (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 the affected area in your heart and heat or freezing is used to correct the problem with the electrical system (this permanently cures the problem in most people)

Find out more about:

• cardioversion: British Heart Foundation
• catheter ablation: British Heart Foundation