Wolff–Parkinson–White syndrome

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Background

Graphic representation of the bundle of Kent in Wolff–Parkinson–White syndrome
  • Abbreviation: WPW
  • Congenital pre-excitation syndrome
  • Presence of an accessory electrical pathway between atria and ventricles predisposing to supraventricular tachycardia
  • Associated with certain genetic predispositions, Ebstein anomaly, and hypokalemic periodic paralysis[1] [2]

Types by Aberrant Pathway Site

  • Type A
    • Pathway between the left atrium and ventricle
    • Delta wave and QRS complex predominantly upright in precordial leads [3]
    • Dominant R wave (greater than S amplitude) in V1 may have appearance of right bundle branch block [4]
  • Type B
    • Pathway between the right atrium and ventricle
    • Delta wave and QRS complex predominantly negative in V! and V2
    • Delta wave and QRS complex predominantly positive in other precordial leads [5]
    • Appearance of left bundle branch block [6]

Types by Cycle Direction

  • Orthodromic
    • Accessory pathway with retrograde reentry conduction
    • Most common variant (~95% of cases)
    • QRS narrow (delta wave absent)
      • Referred to as 'concealed' accessory pathway [7]
    • May see ST depression, TWI
    • Rate 150-250 bpm
  • Antidromic
    • Accessory pathway with anterograde reentry conduction
    • Least common variant (~5% of cases)
    • QRS wide, delta wave present
    • Rate 160-220 bpm, regular

Atrial Fibrillation and Flutter[8]

  • Atrial fibrillation in up to 20% of patients with WPW
    • Irregular rhythm, wide QRS complexes
    • Changing QRS complexes in shape and morphology
    • Axis remains stable as opposed to polymorphic VT
  • Atrial flutter in ~7% of patients with WPW
    • Similar features to atrial fibrillation with WPW
    • Except regular rhythm
    • Easily mistaken for monomorphic ventricular tachycardia
    • Note that if unclear, always safest to assume VT and treat with shock
  • Treatment with AV nodal blocking agents (adenosine, beta-blockers, calcium-channel blockers, amiodarone, digoxin) may incite ventricular fibrillation or ventricular tachycardia
  • "Manifest WPW" = degeneration into VT or VF

Clinical Features

  • Suspect in any patient with ventricular rate >300
  • Many are asymptomatic

Infants

  • Irritability, feeding intolerance
  • CHF
  • Intercurrent febrile illness

Children

  • Chest pain, palpitations
  • Shortness of breath
  • Syncope/near-syncope

Adults

  • Sudden onset "racing heart"

Differential Diagnosis

Narrow-complex tachycardia

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

^Fixed or rate-related

Palpitations

Evaluation

Workup

Delta wave

Diagnosis

12 lead electrocardiogram showing classic findings

Although the ECG and an electrophysiology study are diagnostic, the characteristic features are not always seen on ECG

  • Short PR interval - <0.12sec
  • Delta wave / slurred upstroke
    • Due to early activation of ventricular myocardium
  • QRS duration > 0.10 sec
    • Represents a fusion beat
  • Dominant R wave in V1, Type A WPW
    • Left sided accessory pathway
  • Dominant S wave in V1, Type B WPW
    • Right sided accessory pathway
  • Tall R waves in V1-V3 with T wave inversion
    • Mimic RVH
  • "Negative" delta waves in III and aVF
    • Appear as pseudo-infarct Q waves
    • Mimics prior inferior infarct

Management

Orthodromic

Treat like paroxysmal SVT

Antidromic

Treat like ventricular tachycardia

Atrial Fibrillation and Atrial Flutter

  • Stable
  • Unstable - synchronized cardioversion
    • Consider higher joule dosage and frequency of repeats than for stable
  • Avoid AV nodal blocking agents

Disposition

Discharge

  • Consider if dysrhythmia was easily terminated and can arrange outpatient EP study with possible RF catheter ablation
  • Consider consulting cardiologist regarding outpatient beta-blockers vs. more potent medications (amiodarone, sotalol, flecainide, etc.)

Admit[9]

See Also

External Links

WPW with AFIB

References

Authors:

Ross Donaldson