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Key Features

  • Two classic features of Wolff-Parkinson-White (WPW) pattern on ECG

    • Short PR interval

    • Wide, slurred QRS complex due to manifest preexcitation (delta wave)

  • Most patients with WPW pattern do not have clinical history of arrhythmia but have a higher risk of sudden cardiac death due to rapidly conducted atrial fibrillation through the accessory pathway

  • Risk factors

    • Age younger than 20

    • History of tachycardia

    • Rapid conduction properties at electrophysiologic testing

Clinical Findings

  • Accessory pathways occur in 0.1–0.3% of the population and facilitate reentrant arrhythmias

  • Orthodromic reentrant tachycardia

    • Accounts for ~ 90% of atrioventricular reciprocating tachycardia (AVRT) episodes

    • Characterized by conduction antegrade down the AV node and retrograde up the accessory pathway, resulting in a narrow QRS complex (unless an underlying bundle branch block or interventricular conduction delay is present)

  • Antidromic reentrant tachycardia

    • Conducts antegrade down the accessory pathway and retrograde through the AV node

    • Results in a wide QRS complex

  • Atrial fibrillation or flutter with antegrade conduction down the accessory pathway and a rapid ventricular response seen in up to 30% of patients with Wolff-Parkinson-White syndrome

Diagnosis

  • Some patients have a delta wave found incidentally on ECG

  • Exercise treadmill testing useful in determining if preexcitation is lost at rapid rates

  • Electrophysiologic testing with possible catheter ablation useful to ensure patients are not at an increased risk for syncope or sudden death

    • Patients found to have the shortest preexcited R-R interval (SPERRI) during atrial fibrillation of ≤ 250 msec or inducible supraventricular tachycardia are at increased risk for sudden cardiac death

    • Should undergo catheter ablation

Treatment

  • For narrow-complex reentrant rhythms involving a bypass tract (orthodromic AVRT)

    • Vagal maneuvers

    • Intravenous adenosine

    • Intravenous verapamil

  • For wide-complex tachycardia in the presence of an accessory pathway, be it reentrant-type (antidromic AVRT) or atrial fibrillation with antegrade conduction down the bypass tract

    • Intravenous class Ia (procainamide) and class III (ibutilide) antiarrhythmic agents

      • Medications of choice

      • Increase the refractoriness of the bypass tract

    • If hemodynamic compromise is present, electrical cardioversion is warranted

    • Agents such as calcium channel blockers and beta-blockers should be avoided because of increased risk of ventricular fibrillation

  • Agents such as calcium channel blockers, and beta-blockers should be avoided

  • Amiodarone can be effective in refractory cases

  • If hemodynamic compromise is present, electrical cardioversion is warranted

  • Radiofrequency ablation is the procedure of choice for long-term management of patients with accessory pathways and recurrent symptoms

  • For patients not a candidate for catheter ablation, class Ic or class III antiarrhythmic medication may be considered

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