Wolff-Parkinson-White Syndrome (WPW)
In WPW, an abnormal accessory (extra) pathway (electrical circuit) runs between the atria and ventricles so the electrical signal arrives at the ventricle sooner than normal. This will produce characteristic changes on the electrocardiogram (EKG). Many people with WPW have no symptoms and no episodes of supraventricular tachycardia (SVT). However, about 1/3 of asymptomatic patients may eventually develop symptoms during their lifetime. Most infants presenting SVT do not have recurrent SVT for many years. However, 1/3 will have recurring symptoms by age 8. Patients older than 5 years of age presenting with SVT will have recurrent symptoms in over 75% of cases.
Patients with WPW will undergo a complete cardiovascular evaluation including more tests of the heart’s electrical system. Medications can often prevent recurrent episodes of SVT. Vagal maneuvers (see Table #1 under SVT) can terminate an episode of SVT.
Patients with prolonged episodes of SVT may develop symptoms (see Supraventricular Tachycardia). Risk of sudden cardiac death is very low, about 0.1% or .0002/patient/year. Several risk factors have been identified including multiple accessory pathways, fainting spells, recurrent SVT, underlying congenital heart defects or cardiomyopathy. An electrophysiologic study (EP testing) usually is recommended, especially in symptomatic and older patients or those with risk factors. EP testing may help identify other risk factors and is performed prior to endocardial catheter ablation.