Wolff-Parkinson-White Syndrome

Aka: Wolff-Parkinson-White Syndrome, Wolff-Parkinson-White, WPW Syndrome

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II. Definitions

  1. Wolff-Parkinson-White Syndrome
    1. Arrhythmia associated with AV bypass tract (accessory path outside the AV nodal path)
    2. Subtype of Atrioventricular Reciprocating Tachycardia (AVRT) distinguised by its delta wave

III. Epidemiology

  1. Prevalence: 2 per 1000 general population

IV. Pathophysiology

  1. Subtype of Atrioventricular Reciprocating Tachycardia (AVRT)
    1. Delta wave and Short PR Interval
    2. Prolonged QRS Duration
    3. Anterograde conduction via the accessory path
  2. Atrioventricular bypass tract
    1. Circumvents normal PR Interval delay (up to 0.2 sec)
    2. Allows for ventricular pre-excitation
  3. Predisposes to 3 classic Dysrhythmias
    1. Orthodromic Atrioventricular Reciprocating Tachycardia (AVRT, 65-80%, narrow complex)
      1. See Orthodromic AVRT
    2. WPW-Related Paroxysmal Atrial Fibrillation (20-25%)
      1. Wide Complex Tachycardia often with atypical appearing QRS Complexes
        1. QRS Complexes show beat-to-beat variability in morphology, amplitude and width
        2. Narrow QRS Complexes may be intermittently seen
        3. QRS results from the fusion of the accessory and AV nodal pathway transmissions
      2. Rapid ventricular rates often >220 bpm
      3. Irregularly irregular rhythm
    3. Antidromic Atrioventricular Reciprocating Tachycardia (AVRT, <10%, wide complex)
      1. See Antidromic AVRT

V. Findings: EKG changes

  1. Precautions
    1. WPW EKG Findings may be variably present
    2. Classic findings are more prominent with Valsalva Maneuver (or other increased vagal tone)
  2. Narrow or Short PR Interval (PR <0.12)
    1. Bypass tract results in faster conduction through the AV Node and earlier ventricular depolarization
    2. Look closely for Delta wave when a narrow PR Interval is identified on EKG
  3. Delta wave
    1. Slurred upstroke of QRS (hockey stick appearance)
    2. Bypass tract impulse reaches ventricular Myocardium before AV Node conduction (ventricular pre-excitation)
      1. Resulting ventricular impulses are cell-to-cell and slower than bundle branch conduction
    3. Slurred QRS appearance results from the fusion of 2 depolarization waves
      1. Early bypass tract impulses depolarizing ventricular Myocardium cell-to-cell (wide)
      2. Normal AV Node impulses depolarizing the bundle branches (narrow)
    4. Concealed accessory paths conduct only retrograde, and do NOT have a delta wave
  4. Slightly Wide QRS
    1. Wide QRS related to delta wave (to extent that PR Interval is narrowed)
  5. Pseudoischemic Changes
    1. Q Waves associated with abnormal depolarization
    2. ST Segment deviation and T Wave Inversion associated with abnormal repolarization
  6. Images
    1. ekg20214a_1_svtToWpw.jpg

VI. Differential Diagnosis

  1. Right or Left Bundle Branch Block (wide complex)
  2. Myocardial Infarction (Q Wave when QRS negative)

VII. Precautions

  1. Agents to avoid in WPW (may accelerate Arrhythmia via accessory path)
    1. Adenosine
    2. Beta Blockers (e.g. Metoprolol)
    3. Calcium Channel Blockers (e.g. Verapamil, Diltiazem)
    4. Digoxin (Lanoxin)
  2. Have a high index of suspicion in young patients with Syncope
    1. WPW may be present despite an absence of Short PR Interval and a Delta Wave
  3. Sinus Tachycardia can still occur with all of the typical reasons seen in patients without WPW
    1. Consider Dehydration, infection, Pulmonary Embolism in the differential in a patient with WPW and Tachycardia

VIII. Management

  1. See Unstable Tachycardia
  2. Safe interventions in WPW
    1. Synchronized Cardioversion (preferred)
    2. Procainamide
  3. Avoid AV Nodal blocking agents (esp. in WPW-Related Paroxysmal Atrial Fibrillation)
    1. Contraindicated AV nodal blockers include Beta Blockers, Calcium Channel Blockers, Adenosine, Amiodarone
    2. AV nodal blockade may potentiate the unregulated accessory pathway increasing the ventricular rate (V fib risk)
    3. Any negative inotrope may also worsen hemodynamic collapse

IX. Complications

  1. Atrioventricular Re-Entry Tachycardia (AVRT)
    1. Rates are typically very high (200-300 bpm)
    2. Reentrant Paroxysmal Supraventricular Tachycardia
      1. Orthodromic AVRT in most cases (Antidromic AVRT is much less common)
  2. Atrial Fibrillation (20% of WPW patients)
    1. When associated with preexcitation, may degenerate into Ventricular Fibrillation
  3. Atrial Flutter (7% of WPW patients)
  4. Ventricular Tachycardia or Ventricular Fibrillation
  5. Sudden Cardiac Death

X. References

  1. Braude, Swadron and Orman et. al. in Herbert (2012) EM:RAP 12(7): 1-2
  2. Goldberger (1999) Clinical Electrocardiography, p 127-8
  3. Grauer (2001) 12 Lead EKG, p. 27
  4. Joshi and Dermark (2016) Crit Dec Emerg Med 30(8):3-12
  5. Layng, Vandersteenhoven, Brady (2025) Crit Dec Emerg Med 39(8): 16-7
  6. Vandersteenhoven, Brady (2025) Crit Dec Emerg Med 39(10): 15-7

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