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 Arrhythmia
    1. Reentrant Paroxysmal Supraventricular Tachycardia
    2. Paroxysmal Atrial Fibrillation

V. Types

  1. Anterograde Reciprocating Tachycardia (80% of cases)
  2. Atrial Fibrillation (20% of cases)

VI. 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 PR Interval
    1. Due to pre-excitation of ventricle
    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. Wide QRS related to delta wave (to extent that PR Interval is narrowed)
    3. Concealed accessory paths conduct only retrograde, and do NOT have a delta wave
  4. Other changes
    1. ST and T Wave deflections that are discordant (opposite) to the QRS deflection
  5. Images
    1. ekg20214a_1_svtToWpw.jpg

VII. Differential Diagnosis

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

VIII. 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

IX. Management

  1. See Unstable Tachycardia
  2. Safe interventions in WPW
    1. Amiodarone
    2. Procainamide
    3. Synchronized Cardioversion

X. Complications

  1. Atrioventricular Re-Entry Tachycardia (AVRT)
    1. Rates are typically very high (200-300 bpm)
  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

XI. References

  1. Braude, Swadron and Orman et. al. in Majoewsky (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

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