Supraventricular tachycardia (SVT)


In many cases, symptoms of supraventricular tachycardia (SVT) stop quickly and no treatment is needed.

However, if necessary, treatment is available to stop an episode of SVT and prevent future episodes.

Stopping an SVT episode

Vagal manoeuvres

Vagal manoeuvres are techniques designed to stimulate the vagus nerve. Stimulating this nerve can reduce the speed of the electrical impulses in your heart and stop episodes of SVT. However, these techniques work in less than one in three cases.

One of the main vagal manoeuvres used is called the Valsalva manoeuvre. There's no standard way to perform this manoeuvre, but it often involves holding your nose, closing your mouth and trying to exhale hard while straining as if you were on the toilet. If you're in hospital, you may be asked to blow hard into a tube instead.

You can perform a simple version of the Valsalva manoeuvre at home to try to stop an episode of SVT. You can also try dipping your face into a bowl of cold water, as this can have a similar effect.

An alternative vagal manoeuvre is a carotid sinus massage. This involves massaging an area of your neck called the carotid sinus in an attempt to stimulate the vagus nerve. However, this should only be carried out by a healthcare professional and shouldn't be attempted at home.


If vagal manoeuvres are unsuccessful, you may need an injection of a medication called adenosine in hospital. This medication blocks the abnormal electrical impulses in your heart.

Side effects of adenosine are relatively common, but usually short-lived. After an injection, you may experience nausea (feeling sick), dizziness, chest tightness or shortness of breath.

An injection of verapamil may sometimes be used instead of adenosine, but only usually if adenosine is unsuitable (for example, if you have asthma). This is because there's a risk of more serious side effects, including low blood pressure.


If a prolonged episode of SVT doesn't respond to vagal manoeuvres or medication, or if these treatments are unsuitable, a treatment called cardioversion may be used.

Cardioversion is a relatively simple procedure that uses a defibrillator to apply an electrical current to your chest. This shocks the heart back into a normal rhythm.

It's usually carried out under general anaesthetic and you should be able to go home the same day.

Cardioversion is a very effective procedure and serious complications are uncommon. However, your chest muscles may feel sore afterwards and the areas of skin where the electrical shocks were applied may be red and irritated for a few days.

Preventing future SVT episodes

There are also some treatments that reduce your chances of having further SVT episodes.

Lifestyle changes

Some SVT episodes are triggered by things like tiredness, drinking lots of alcohol or caffeine, or smoking lots of cigarettes.

Cutting down on the amount of caffeine or alcohol you drink, stopping or limiting how many cigarettes you smoke, and making sure you get enough rest can reduce your chances of having further episodes.

Read more about stopping smoking and tiredness and fatigue.


If necessary, medication can be prescribed to prevent further episodes of SVT by slowing down the electrical impulses in your heart. These medications are taken as a daily tablet and include digoxin, verapamil and beta-blockers.

Common side effects of these medications can include dizziness, diarrhoea and blurred vision. Tiredness can occur with beta-blockers and men may experience problems getting erections. Less common side effects include difficulty getting to sleep (insomnia) and depression.

If the medication you're prescribed doesn't work or has unpleasant side effects, a more suitable alternative can often be found.

Catheter ablation

If you have repeated episodes of SVT, an operation called catheter ablation is the recommended treatment option. This prevents further episodes of SVT by destroying the tiny parts of the heart causing the problems in the heart's electrical system.

Catheter ablation is a safe and highly effective treatment, and means you no longer need to take medication. It cures SVT in over 95% of people and is the recommended treatment worldwide.

During catheter ablation, a thin wire called a catheter is inserted into a vein in your upper leg or groin, before being guided to your heart by an electrophysiologist (a heart specialist who specialises in abnormal heartbeats and rhythms). When the wire reaches the heart, it records the electrical activity to pinpoint the precise location of the problem.

When the problem area is found, high-frequency radiowaves are transmitted to the catheter tip to destroy it, producing a small scar.

You'll remain awake during this procedure, but will be given a sedative to relax you. Local anaesthetic will be used to numb the area where the catheter is inserted. 

The procedure lasts about an hour and a half and you can usually go home on the same day you have the procedure. However, there may be instances where you need to stay in hospital overnight – for example, if you're operated on in the late afternoon.

Catheter ablation is very effective at preventing future episodes of SVT (19 out of every 20 people treated will never have the problem again), but like all operations it carries a risk of complications. These include bruising and bleeding where the catheter was inserted. Any bruising will usually be small, but even if you have a large bruise it won't require any treatment and will disappear within two weeks.

There's also a small risk (less than 1 in 100) of the heart's normal electrical system being damaged. This is known as heart block, and if it happens you may need a permanent pacemaker to control your heart rhythm.

You should discuss potential benefits and risks of catheter ablation with your surgeon (the electrophysiologist) before the procedure.

Page last reviewed: 08/05/2015
Next review due: 01/05/2018