Affected children present with chest pain or chest tightness accompanied with dyspnoea, paroxysmal nocturnal dyspnoea and palpitations. These symptoms may be accompanied by light headedness and dizziness, and sometimes the child may faint during an acute attack.
Other signs and symptoms may include pallor, irritability, tachypnoea and slight behavioural changes. Once the tachycardia episode is over, symptoms may disappear and the affected individual may return to normal
Diagnosis of WPW syndrome can not be made without a complete work up first. After a detailed history and physical examination, the following tests should be conducted to rule out any other cause.
Treatment consists of medication with radiofrequency ablation or open heart surgery.
In acute cases of arrhythmia, procainamide or amiodarone are the drugs of choice. Adenosine may also be given. Digoxin and calcium channel clockers should be avoided because they block the normal AV node and promote abnormal conduction in the accessory pathway.
It is the first line of therapy in symptomatic patients and is curative. A wire (electrode catheter) is advanced into the heart from large blood vessels and positioned within the chambers of the heart using fluoroscopy. After the accessory pathway is localised, radio frequency energy is delivered to the area to destroy or 'ablate' the accessory pathway, preventing it from conducting impulses .
An open heart surgery may be performed to disconnect the pathway through which supraventricular excitations pass in WPW syndrome. The success rate for surgical ablation is close to 100% and the complication rate is low. However, radiofrequency ablation is a less invasive option; as a result, surgery is now rarely performed .
If correctly diagnosed and appropriately treated, the Wolff-Parkinson-White syndrome has an excellent prognosis. The success rate of treatment is almost 100%.
Asymptomatic patients generally have the best prognosis and symptomatic patients that are appropriately treated also achieve a long healthy life. However, some patients have a family history of arrhythmias or they may have other heart defects in which case, the prognosis becomes negatively affected.
Although periods of tachycardia are not life threatening, patients can develop serious heart problems . Complications include trauma due to fainting, heart failure, hypotension, surgical complications, other arrhythmias like ventricular fibrillation (VF), etc.
VF is the most severe from of a rapid heart beat. It may rapidly lead to shock and death, and requires emergency treatment (cardioversion)  .
The genesis of reentrant supraventricular tachycardia (SVT) involves the presence of dual conducting pathways between the atria and the ventricles . These accessory pathways such as the bundle of Kent, allow reentry of impulses resulting in arrhythmias.
It may be inherited as a familial trait, with or without associated congenital heart defects . The inheritance pattern is autosomal dominant, but in some extremely rare cases, it can be a result of mitochondrial inheritance. Mutations in the gamma 2 subunits of AMP activated protein kinase (PRKAG2), a protein kinase enzyme, encoded by the PRKAG2 gene  result in cardiomyopathies characterised by WPW syndrome, AV blocks and ventricular hypertrophy.
In rare cases, certain tumors present around the AV node or along the AV pathway and may cause WPW syndrome.
Incidence and Prevalence
The prevalence of Wolff-Parkinson-White syndrome is between 0.1% and 0.3% in the general population . Among these, sudden cardiac death is rare with an incidence of less than 0.6% .
WPW syndrome commonly exhibits bimodal presentation, occurring either in infancy or between 5 to 15 years of age. It is rare in old age and in fact, incidence of WPW syndrome decreases with increase in age.
Studies reveal a predisposition in males, with the male to female ratio somewhere around 2:1. A 3.5 fold higher prevalence in boys and young men was also shown by another study.
WPW syndrome exhibits no known predisposition to any race or demographic.
According to the type of tachycardia and ECG changes produced and well as the pathway of reentry, WPW syndrome can be subdivided into three types:
In this type, the ventricles are depolarised through the AV node and accessory pathway. It produces a shortened PR interval and delta waves.
It is the most common type of tachycardia in WPW syndrome. The reentry circuit passes antegradely through the AV node and retrogradely through the accessory pathway, producing a narrow complex tachycardia like a SVT. Sometimes, the QRS complex may be normal, delta waves may be absent and p waves may be typically inverted on lateral and inferior leads.
Pre-Excitatory Atrial Fibrillation/Antidromic Tachycardia
In this type, ventricles are largely depolarised by the accessory pathway producing an irregular, broad complex tachycardia. It is the most rare type occurring in only 5% of cases and can be easily confused with ventricular tachycardias.
WPW syndrome has no known prevention. However, once diagnosed, the episodes of tachycardia may be prevented by the above mentioned treatments like ablation and medication.
Wolff-Parkinson-White (WPW) syndrome is a heart condition in which there is an abnormal extra electrical pathway of the heart . It is defined as an ECG pattern sometimes associated with paroxysmal tachycardia. It consists of a short PR interval (usually 0.1 second or less;occasionally normal) together with a prolonged QRS complex with a slurred initial component (delta wave) .
In WPW syndrome, an accessory bundle of impulse pathway known as the bundle of Kent is present which sends preexcitatory impulses down to the ventricles causing arrhythmias.
WPW syndrome is one of the most common causes of tachycardia in infants and children. It is due to a congenital defect in the excitatory circuit pathway of the heart and can be successfully treated with ablation.
If an infant appears to resist feeding, becomes cyanotic or pale with an apparent strain on breathing and becomes irritable, the infant should be immediately checked for WPW syndrome. A child old enough to express himself may complain of chest pain, palpitations, dizziness, lethargy and difficulty in breathing during episodes of tachycardia.