History
Patients with Wolff-Parkinson-White (WPW) syndrome may present with anything from mild chest discomfort or palpitations with or without syncope to severe cardiopulmonary compromise or cardiac arrest.
An infant with WPW syndrome may frequently be irritable, may not tolerate feedings, or may demonstrate evidence of congestive heart failure (CHF). Infants often have a history of not behaving as usual for 1-2 days. An intercurrent febrile illness is often observed.
A verbal child with WPW syndrome usually reports chest pain, palpitations, or breathing difficulty. Most children are previously well, and a minority of children have a positive family history of this condition.
Older patients can usually describe the sudden onset of a pounding heartbeat, which is regular and “too rapid to count.” This is typically accompanied by a concomitant change in their tolerance for activity. An irregular rhythm may herald the presence of atrial fibrillation (AF). Occasionally, evidence of disease is discovered on routine electrocardiography (ECG), independent of a concurrent tachydysrhythmia.
In patients with WPW syndrome, the tachycardia that produces symptoms may be a supraventricular tachycardia (SVT), AF, or atrial flutter. In a series of 212 patients with tachyarrhythmias and WPW syndrome, SVT alone occurred in 64%, AF alone occurred in 20%, and both occurred in 16% of patients.
SVT in WPW syndrome may begin in childhood or may not appear clinically until the patient reaches middle age. The clinical course can be unpredictable, as SVT induction depends upon changes in accessory pathway and often AV node EP properties that can vary with time.
SVT due to reentry in WPW is typically orthodromic tachycardia in 95% and antidromic tachycardia in 5% (see Pathophysiology). Orthodromic SVT is usually well tolerated and not a high risk, especially in the pediatric population after young infancy. Antidromic SVT presents more frequently with dizziness and syncope. In addition, it may precipitate ventricular tachycardia and ventricular fibrillation (VF).
Light-headedness and near syncope appear to occur more commonly in persons with WPW syndrome who have paroxysmal SVT (PSVT) or atrial fibrillation than in those with atrioventricular (AV) nodal reentry.
Syncope can occur because of inadequate cerebral circulation due to a rapid ventricular rate or because the tachyarrhythmia is depressing the sinus pacemaker, causing a period of asystole at the point of tachycardia termination.
PSVT can be followed after termination by polyuria, which is due to atrial dilatation and release of atrial natriuretic factor.
Physical Examination
WPW syndrome has no specific examination features except for those that may accompany symptomatic dysrhythmias. The vast majority of WPW patients have normal cardiac examination findings.
Many young patients appear may present with resting tachycardia on physical examination, with only minimal symptoms (eg, palpitations, weakness, mild dizziness) despite exceedingly fast heart rates. Upon physical examination, the patient may be cool, diaphoretic, and hypotensive. Crackles in the lungs are common because the rapid heart rate may cause pulmonary vascular congestion due to CHF.
During SVT, the rhythm is unvarying and regular, with constant intensity of the first heart sound. The jugular venous pressure can be elevated, but the waveform generally remains constant.
An infant experiencing an episode of SVT is usually tachypneic and irritable; pallor is common. The pulse is very rapid and diminished in volume. The ventricular rate typically is 200-250 bpm, and the blood pressure is decreased. If the episode has been untreated for several hours, the patient often has poor perfusion, hepatomegaly, and cardiac failure. The child is usually anxious but hemodynamically stable. Tachypnea often accompanies the tachycardia.
Once the arrhythmia has been terminated, the physical examination findings are generally normal.
Clinical features of associated cardiac defects may be present, such as the following:
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Cardiomyopathy
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Hypertrophic cardiomyopathy ( AMPK mutation) [2]
In the presence of congenital heart defects (CHDs) or cardiomyopathy, findings of the underlying condition often become apparent only after the SVT has been terminated, although the hemodynamic consequences may be poorly tolerated.
In several series, the incidence of associated congenital heart disease is reported to be as high as 30%, most commonly Ebstein anomaly of the tricuspid valve and corrected transposition of the great arteries.
Approximately 10% of patients with Ebstein anomaly of the tricuspid valve have WPW syndrome. They usually have more than 1 accessory pathway (AP), and those are usually on the right side. Patients with corrected transposition of the great arteries and left-side Ebstein anomaly may also have WPW syndrome. In these patients, the AP is on the left side or septal.
Patients with Ebstein anomaly of the tricuspid valve may present with cyanosis, tachypnea, and other signs of congestive heart failure in presence of a rapid heart rate. ECG may show either wide or narrow QRS, SVT, and, sometimes, QRS with changing morphology if more than one AP is present. Patients with right-side accessory pathways should be screened for the Ebstein anomaly by echocardiography.
Patients with glycogen-storage diseases have muscle weakness with normal or increased muscle bulk, macroglossia and hepatomegaly in the case of Pompe disease, and mental retardation in case of Danon disease.
Other congenital heart diseases associated with WPW syndrome include atrial and ventricular septal defects and coronary sinus diverticula.
The abnormal QRS complexes of WPW syndrome, when present, may appear similar to those observed in acute myocardial infarction (MI), left ventricular hypertrophy (LVH), and hypertrophic cardiomyopathy. Repolarization abnormalities are common in patients with WPW syndrome, and thus, acute MI and LVH cannot be diagnosed if a delta wave is present.
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Classic Wolff-Parkinson-White electrocardiogram with short PR, QRS >120 ms, and delta wave.
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Preexcited atrial fibrillation.
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Variants of Wolff-Parkinson-White syndrome (unusual accessory pathways).
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Accessory pathway potential and local AV fusion at successful RF ablation site with loss of preexcitation and return of normal HV interval.
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Electrocardiogram of asymptomatic 17-year-old male who was incidentally discovered to have Wolff-Parkinson-White pattern. It shows sinus rhythm with evident preexcitation. To locate accessory pathway (AP), initial 40 ms of QRS (delta wave) is evaluated. Note that delta wave is positive in I and aVL, negative in III and aVF, isoelectric in V1, and positive in rest of precordial leads. Therefore, this is likely posteroseptal AP.
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12-lead electrocardiogram from asymptomatic 7-year-old boy with Wolff-Parkinson-White pattern. Delta waves are positive in I and aVL; negative in II, III, and aVF; isoelectric in V1; and positive in rest of precordial leads. This predicts posteroseptal location for accessory pathway.
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12-lead electrocardiogram showing short PR interval and delta waves consistent with presence of accessory pathway.
