Overview
Wolff-Parkinson-White (WPW) syndrome is a congenital disorder characterised by an accessory pathway that allows the conduction of electrical impulses from the atria to the ventricles directly, bypassing the atrioventricular (AV) node. This leads to AV re-entry tachycardia (AVRT) and can cause paroxysmal supraventricular tachycardia. This can also trigger ventricular fibrillation and cause sudden cardiac death.
WPW is a type of pre-excitation syndrome.
Epidemiology
- WPW is relatively common and found in up to 3 people per 1,000
- WPW is found in all ages but is more common in younger people
Associations
WPW syndrome is associated with:
- Ebstein’s anomaly
- Hypertrophic obstructive cardiomyopathy
- Hyperthyroidism
- PRAKAG2 – this is a gene associated with a familial form of WPW syndrome
Investigations
- ECG:
- PR interval is short
- QRS complexes are wide with a slurred upstroke known as a delta wave
- Associated left axis deviation or right axis deviation
Figure 1: ECG findings in WPW syndrome. There is a slurred upstroke at the start of the QRS complex (delta wave)
Management
Overview
The definitive management step involves radiofrequency ablation of the accessory pathway. Initial management steps of an acute episode are similar to supraventricular tachycardia such as vagal manoeuvres except adenosine is not used if co-existing atrial fibrillation is suspected:
- This is because adenosine blocks the AV node which can increase the ventricular rate potentially leading to ventricular fibrillation.
Sotalol should also be avoided for the same reasons.
