Genetic disorder that allows abnormal conduction to occur in the heart via an accessory pathway

Aetiology

• Congenital condition
• Twice more common in males

Pathophysiology

• Patients possess an accessory pathway known as the Bundle of Kent which allows the signal to return to the atria from the ventricles
• This creates a re-entrant loop that predisposes to supraventricular tachycardias e.g. atrial fibrillation, AVRT

Clinical features

• Often asymptomatic incidental finding
• Acute episodes of SVT - palpitations, dyspnoea, tachycardia, dizziness, syncope

Investigations

ECG

• Slurred upstroke on the QRS complex (delta wave) - pre-excitation
• Short PR interval (< 0.12 seconds)
• Broad QRS complex (> 0.12 seconds)
• If a re-entrant circuit has developed the ECG will show a narrow complex tachycardia

Other investigations

• 24 hour ECG monitoring if paroxysmal symptoms