Wolff-Parkinson-White syndrome is a heart condition featuring episodes of an abnormally fast heart rate.
The condition is present at birth and one of the most common causes of an abnormally fast heart rate in infants and children. However, Wolff-Parkinson-White syndrome is sometimes not detected until later in life.
The heart will suddenly start racing, then stop or slow down abruptly. This rapid heart rate is called supraventricular tachycardia#a> (SVT).
Episodes can last for seconds, minutes, hours or (in rare cases) days. They may occur regularly, once or twice a week, or just once in a while.
When someone with Wolff-Parkinson-White syndrome has SVT, their heart rate may be as high as 230 beats per minute (bpm). At rest, a normal adult heart rate is 60-100 bpm, and up to around 150 bpm in babies and children.
In rare cases of Wolff-Parkinson-White syndrome, the patient's heart rate can go extremely fast when a heart rhythm called atrial fibrillation occurs. The combination of Wolff-Parkinson-White syndrome and atrial fibrillation can be life-threatening.
When the heart beats normally, its muscular walls contract (tighten and squeeze) to force blood out and around the body. They then relax, so the heart can fill with blood again (see "How the heart works" in the box on this page).
In Wolff-Parkinson-White syndrome, electrical signals in the heart can travel round and round in a loop, causing the heart to beat very fast. The heart muscle is contracting so fast that it cannot relax between contractions. This reduces the amount of blood being pumped around the body, which can make you feel:
- short of breath
- faint (if a person with Wolff-Parkinson-White syndrome collapses or faints, an ambulance should be called immediately)
You may also feel heart palpitations (noticeable heartbeats), a fast pulse and chest tightness.
When someone with Wolff-Parkinson-White syndrome does not experience palpitations, the condition can be harder to diagnose and it may only be picked up during a test called an ECG (electrocardiogram), when this test is done for another reason.
Why it happens
Wolff-Parkinson-White syndrome is caused by an extra electrical connection in the heart. This allows electrical signals to bypass the usual route and form a short circuit, causing an abnormally fast heart rhythm.
The extra electrical circuit is caused by a strand of muscle that grows from the atria to the ventricle during the development of a foetus into a baby. It rarely runs in families, usually occurring randomly in some babies.
A few people with Wolff-Parkinson-White syndrome also have a structural problem with their heart or underlying heart disease. For example, Wolff-Parkinson-White syndrome is sometimes associated with a heart valve problem called Epstein anomaly.
How it is diagnosed
If your doctor thinks you have Wolff-Parkinson-White syndrome after assessing your symptoms, they may ask you to have an ECG and refer you to a heart specialist, who is also known as a cardiologist.
An ECG is a test that records the rhythm and electrical activity of your heart. Small stickers, called electrodes, are stuck on your arms, legs and chest and connected by wires to an ECG machine.
Every time your heart beats, it produces tiny electrical signals. An ECG machine traces these signals on paper.
If you have Wolff-Parkinson-White syndrome, the ECG will record an abnormal "delta wave" (a type of brain wave).
However, it may be difficult to capture an attack of a racing heart and palpitations, so your doctor may ask you to wear a small, portable electrocardiogram recorder. This will trace your heart rate either continuously over 24 hours or when you switch it on at the start of an attack.
Treatment and outlook
In the vast majority of cases, episodes of Wolff-Parkinson-White syndrome are harmless, do not last long and settle on their own without treatment.
If your heart races fast for 20 minutes without a break, go to your nearest hospital accident and emergency (A&E) department where you will receive an injection to stop it.
Your doctor will probably not want to prescribe any medication for Wolff-Parkinson-White syndrome without first referring you to a cardiologist on at least one occasion.
Wolff-Parkinson-White syndrome can also be permanently treated with a very effective surgical procedure called catheter ablation. This involves inserting a soft plastic coated wire into an artery or vein at the top of your thigh through a hollow needle, and feeding this up to your heart.
When the tip of the wire reaches the correct place in your heart, radiofrequency energy or cryotherapy is delivered to a point on the heart muscle, damaging the strand of muscle that forms the short circuit. This cures Wolff-Parkinson-White syndrome in most people.