Medical Minute Recap: Tachyarrhythmias in patients with Wolff Parkinson White Syndrome: AFIB

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November 19, 2015 by dailybolusoflr

By: Erin Kane, MD

WPW– Quick review  

  • Accessory pathway directly connects the atria and ventricles, allowing electrical activity to bypass the AV node
  • WPW pattern occurs in 0.13 to 0.25 percent of general population; only 1-2% of those with WPW pattern will have WPW syndrome (i.e., will have a tachydysrhythmia)

WPW pattern on EKG (triad)

  • Short PR 
  • Delta wave / slurred upstroke
  • Prolonged QRS 
  • May not always be present on baseline EKG despite presence of accessory pathway (“concealed” accessory pathway) – pathways that are only capable of retrograde conduction will not have short PR or delta wave 

http://lifeinthefastlane.com/ecg-library/pre-excitation-syndromes/


Possible dysrhythmias 

  • SVT (AVRT – atrioventricular reciprocating tachycardia) with orthodromic or antidromic conduction – 80%, majority of those orthodromic  
  • Atrial fibrillation – 15-20% 

http://lifeinthefastlane.com/ecg-library/pre-excitation-syndromes/


Clinical manifestations

  • Palpitations, lightheadedness, syncope or presyncope, chest pain, sudden cardiac death

Atrial fibrillation in WPW – why it matters 

  • Intrinsic rate of atrial fibrillation is 450-600, but in most patients, the rate is limited by the refractory period of the His-Purkinje system, so not all of these beats are conducted
  • In WPW, the accessory pathway can conduct faster and will conduct more of these beats
  • Ventricular rates can exceed 300 bpm and may degenerate into VF
  • Incidence of sudden death in WPW is low, but when it occurs is due to afib

Atrial fibrillation in WPW – how to identify 

  • Consider in a young patient with no hx cardiac disease presenting with a wide complex tachycardia or in patient with known history of WPW
  • Rhythm is irregular; there is significant beat-to-beat variation between QRS complexes; may have occasional narrow QRS 
  • DDx: SVT with aberrancy, monomorphic VT, polymorphic VT (which is especially difficult to differentiate)

Management

  • If unstable (altered, hypotensive), electrical cardioversion (synchronized so long as R waves can be distinguished)
  • If pharmacologic management, procainamide 30 mg/min
  • Any pharmacologic agent that blocks AV node may cause degeneration into VF and death – DO NOT give calcium channel blockers, beta blockers, adenosine, or digoxin in wide complex tachycardia in known WPW
  • Amiodarone should NOT be used in patients with AF and an accessory pathway  does not slow the accessory pathway and has some beta blocking properties

References

  1. Fengler BT, WJ Brady, and CU Plautz. Atrial fibrillation in the Wolff-Parkinson-White syndrome: ECG recognition and treatment in the ED.  Am J Emerg Med 2007; 25: 576-83.
  2. Rosner MH, WJ Brady, MP Kefer, ML Martin. Electrocardiography in the patient with the Wolff-
  3. Parkinson-White syndrome: Diagnostic and initial therapeutic issues. Am J Emerg Med 1999; 17: 705-14.
  4. Di Biase, L and EP Walsh. Epidemiology, clinical manifestations, and diagnosis of the Wolff-Parkinson-White syndrome. Up to Date. 
  5. Di Biase, L and EP Walsh. Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway. Up to Date. 
  6. Di Biase, L and EP Walsh. Treatment of symptomatic arrhythmias associated with the Wolff-Parkinson-White syndrome. Up to Date. 

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