Wolff-Parkinson-White (WPW) syndrome is a heart condition that causes the heart to beat abnormally fast for periods of time.
It's a relatively common condition, affecting between one and three in every 1,000 people.
The cause is an extra electrical connection in the heart. This problem with the heart is present at birth (congenital), although symptoms may not develop until later in life. Many cases are diagnosed in otherwise healthy adults aged between 20 and 40.
Sometimes the extra electrical connection won't cause any symptoms and may only be picked up when an electrocardiogram (ECG) test is carried out for another reason. In these cases, further tests will be done to determine if treatment is required.
It can be scary to be told that you have a problem with your heart, but WPW syndrome usually isn't serious.
Many people will have no symptoms or only experience occasional, mild episodes of their heart racing. With treatment, the condition can normally be completely cured.
WPW syndrome can sometimes be life-threatening, particularly if it occurs alongside a type of irregular heartbeat called atrial fibrillation. But this is rare and treatment can eliminate this risk.
If you have WPW syndrome, you'll experience episodes where your heart suddenly starts racing, before stopping or slowing down abruptly. This rapid heart rate is called supraventricular tachycardia (SVT).
During an episode, you may experience symptoms such as:
These episodes can last for seconds, minutes or hours. Rarely, they can last for days.
How often they occur varies from person to person. Some people may have episodes on a daily basis, while others may only experience them a few times a year.
They normally occur randomly, without any identifiable cause, but they can sometimes be triggered by strenuous exercise or drinking a lot of alcohol or caffeine.
If you haven't been diagnosed with WPW syndrome, you should contact your GP or call NHS 111 as soon as possible if your heart starts beating unusually fast and you have any of the above symptoms.
Dial 999 for an ambulance if your symptoms are particularly severe or long-lasting.
If you've already been diagnosed with WPW syndrome and you experience an episode, first try the techniques you've been taught or take any medication you've been given (see below).
Dial 999 or go to your nearest accident and emergency (A&E) department if these measures don't stop the episode within a few minutes, or if someone you know has WPW syndrome and collapses or faints.
When the heart beats, its muscular walls contract (tighten and squeeze) to force blood out and around the body. They then relax, allowing the heart to fill with blood again. This is controlled by electrical signals.
In WPW syndrome, there's an extra electrical connection in the heart, which allows electrical signals to bypass the usual route and form a short circuit. This means the signals travel round and round in a loop, causing episodes where the heart beats very fast.
The extra electrical connection is caused by a strand of heart muscle that grows while the unborn baby is developing in the womb.
It's not clear exactly why this happens. It just seems to occur randomly in some babies, although rare cases have been found to run in families.
If your doctor thinks you might have WPW syndrome after assessing your symptoms, they'll probably recommend having an electrocardiogram (ECG) and will refer you to a cardiologist (heart specialist).
An ECG is a test that records your heart's rhythm and electrical activity. Small discs called electrodes are stuck onto your arms, legs and chest and connected by wires to an ECG machine. The machine records the tiny electrical signals produced by your heart each time it beats.
If you have WPW syndrome, the ECG will record an unusual pattern that isn't usually present in people who don't have the condition.
To confirm the diagnosis, you may be asked to wear a small portable ECG recorder so your heart rhythm can be recorded during an episode. The recorder will trace your heart rate continuously over a few days, or when you switch it on at the start of an episode.
In many cases, episodes of abnormal heart activity associated with WPW syndrome are harmless, don't last long, and settle down on their own without treatment.
You may therefore not need any treatment if your symptoms are mild or occur very occasionally, although you should still have regular check-ups so your heart can be monitored.
If your cardiologist recommends treatment, there are a number of options available. You can have treatment to either stop episodes when they occur, or prevent them occurring in the future.
There are three main techniques and treatments that can help stop episodes as they occur. These are:
Techniques and treatments that can help prevent episodes include:
See treating supraventricular tachycardia (SVT) for more information about all the treatments mentioned here.
If you have Wolff-Parkinson-White syndrome, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.