Normally, there is just one electrical pathway connecting these chambers and impulses which generate the heartbeat pass in only one direction (upper to lower).
The extra pathway may allow the normal electrical signal to arrive at the ventricles more quickly than usual, causing “pre-excitation” and producing characteristic changes on the electrocardiogram (ECG).
The extra pathway may at times function as a “short-circuit”, allowing impulses to circulate rapidly down the normal pathway and back up the accessory pathway causing the heart to suddenly beat abnormally fast, in an abnormal heart rhythm called supraventricular tachycardia (SVT). This may last for a few minutes or can persist for several hours.
Should this symptom happen the person will complain of rapid heart beating and may experience palpitations, dizziness, chest tightness and may even faint. Episodes can often begin during exercise.
The most serious situation, which is fortunately very rare, is when people with WPW develop atrial fibrillation (very rapid, irregular, chaotic electrical activity within the atria) which may travel very rapidly down the accessory pathway to the ventricles. This may then cause ventricular tachycardia or fibrillation and cardiac arrest.
Other people with WPW may never have SVT or other symptoms. About 80 percent of people with symptoms, first experience them between the ages of 11 and 50.
This extra pathway is present at birth but may only become apparent as you get older. It is fairly rare and little is known about why it develops.
If treatment is needed, the goal is to slow a fast heart rate when it occurs and to prevent future episodes.
People with WPW usually have a distinctive pattern on the ECG tracing called a ‘delta wave’ which does not appear in people who don’t have the condition.
Your doctor will take a history of any symptoms you have experienced and will likely recommend some further heart tests which may include: a holter monitor to record a 24 hour ECG; an event recorder for a longer period of monitoring which you can activate when symptoms occur; electrophysiology study which will confirm the diagnosis and locate the extra pathway.
People who have episodes of SVT can be treated with long-term medication or can undergo radiofrequency catheter ablation which is curative in 95 to 98% of cases.
Whether an individual will be treated with medication or by an ablation procedure depends on several factors such as the severity and frequency of symptoms, risk for future arrhythmias and patient preference.
Once the condition has been identified and treated appropriately, people with WPW syndrome have an excellent prognosis.
The Irish Heart Foundation offers a range of free support services to those affected by heart disease or stroke that can greatly improve their quality of life. These include support groups, physical exercise classes, therapy sessions and more.
For more information on these supports, see our Patient Supports page.
If you have any questions about heart disease or stroke, you can also call the Irish Heart Foundation’s Nurse Support on (01) 668 5001 to speak to a nurse specialist who will answer your questions, and give you guidance and reassurance.
For more about heart conditions, from diagnosis to prevention and treatment, view our Heart Conditions Explained articles such as: atherosclerosis, angina, heart attack and stroke.
You can also contact our helpline nurses on Freephone 1800 25 25 50 Mon – Fri 9am – 5pm, Thurs till 7pm