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Wolff–Parkinson–White (WPW) Syndrome, Emergency Medicine

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Wolff–Parkinson–White (WPW) Syndrome, Emergency Medicine

Basics

Description

Electrophysiology studies to assess for radiofrequency ablation or surgery may be performed on outpatient basis. пїЅ пїЅ

The patient should be instructed to return to the ED with any symptoms suggestive of a tachydysrhythmia: пїЅ пїЅ

426.7 Anomalous atrioventricular excitation пїЅ пїЅ

  • Syndrome resulting from the presence of an abnormal (accessory) pathway that bypasses the AV node (Kent bundles) between the atria and ventricles
  • Wolff " пїЅParkinson " пїЅWhite (WPW) pattern on the ECG is defined by a short PR interval and a пїЅ пїЅ-wave reflecting early conduction (pre-excitation):Accessory pathways occur in 0.1 " пїЅ0.3% of the population.
  • WPW syndrome requires ECG evidence of the accessory pathway and related tachycardia.
  • Accessory pathways:Small bands of tissue that failed to separate during development:Left lateral (free wall) accessory pathway: Most commonThe posteroseptal region of the AV groove: 2nd most common locationRight free wallAnteroseptal
  • Conduction in WPW may be antegrade, retrograde, or both.
  • Orthodromic re-entrant tachycardia is the most common (70%):Impulse travels antegrade from the atria down the AV node to the ventricle and then retrograde up the accessory pathway.This re-entrant tachycardia is a narrow complex rhythm unless a bundle branch block or intraventricular conduction delay is present.
  • Antidromic is less common (30%):Impulse travels antegrade down the accessory pathway and retrograde through the AV node resulting in a wide quasi-random signal (QRS) complex.
  • Sudden death occurs in 1 per 1,000 patient-years in persons with known ventricular pre-excitation.
  • Accessory pathways occur in 0.1 " пїЅ0.3% of the population.
  • Small bands of tissue that failed to separate during development:Left lateral (free wall) accessory pathway: Most commonThe posteroseptal region of the AV groove: 2nd most common locationRight free wallAnteroseptal
  • Left lateral (free wall) accessory pathway: Most common
  • The posteroseptal region of the AV groove: 2nd most common location
  • Right free wall
  • Anteroseptal
  • Impulse travels antegrade from the atria down the AV node to the ventricle and then retrograde up the accessory pathway.
  • This re-entrant tachycardia is a narrow complex rhythm unless a bundle branch block or intraventricular conduction delay is present.
  • Impulse travels antegrade down the accessory pathway and retrograde through the AV node resulting in a wide quasi-random signal (QRS) complex.

Etiology

  • Idiopathic:Unknown mechanism in most cases, with familial predisposition
  • Rarely inherited as an autosomal dominant trait
  • Associated in rare cases with a familial hypertrophic cardiomyopathy
  • Unknown mechanism in most cases, with familial predisposition

Diagnosis

Signs and Symptoms

  • Asymptomatic
  • Palpitations:Fast or irregular
  • Chest pain
  • Dyspnea
  • Dizziness
  • Diaphoresis
  • Syncope
  • Sudden death (rare)
  • Fast or irregular
  • Tachycardia:Rapid and regular:Supraventricular tachycardiaAtrial flutterIrregular:Atrial fibrillation
  • Signs of instability:Chest painHypotensionChange in mental statusRalesCyanosis
  • Rapid and regular:Supraventricular tachycardiaAtrial flutter
  • Irregular:Atrial fibrillation
  • Supraventricular tachycardia
  • Atrial flutter
  • Atrial fibrillation
  • Chest pain
  • Hypotension
  • Change in mental status
  • Rales
  • Cyanosis

Essential Workup

  • WPW syndrome should be considered the underlying etiology in all cases of tachydysrhythmia.
  • The diagnosis should be based on the characteristic ECG findings.

Diagnosis Tests & Interpretation

  • Cardiac enzymes only if signs of ischemia
  • Consider electrolytes and thyroid disease
  • EKG
  • Pre-excitation:Short PR interval, <0.12 sec пїЅ пїЅ-wave: Small slurred upstroke at the beginning of the QRSProlonged QRS, >0.10 sec with variable morphology linked to specific accessory pathway
  • Left lateral pathway:Positive пїЅ пїЅ-wavesQ-waves with negative to isoelectric deflections in V1 and in the inferior leads:May suggest a former high lateral MI and right axis deviation
  • Posteroseptal accessory pathway:Negative deflecting пїЅ пїЅ-wavesQRS complexes in the inferior leads:Often mistaken for prior inferior MI
  • Tachydysrhythmias:Orthodromic atrioventricular re-entrant tachycardia (OAVRT):The pathway that conducts the impulse to the ventricle is the AV node/His " пїЅPurkinje systemNarrow QRS complex tachycardiaHowever, this may be associated with a wide QRS complex in the presence of a pre-existing or rate-related functional bundle branch block.P-wave following the QRSRate between 150 " пїЅ250 bpmThe пїЅ пїЅ-wave seen during sinus rhythm is lost since antegrade conduction is not via the accessory pathwayAntidromic AVRT:RegularWide QRS complexThe antegrade limb is usually the accessory pathway.Atrial fibrillation:IrregularWide complex with variable QRS morphologies
  • Short PR interval, <0.12 sec
  • пїЅ пїЅ-wave: Small slurred upstroke at the beginning of the QRS
  • Prolonged QRS, >0.10 sec with variable morphology linked to specific accessory pathway
  • Positive пїЅ пїЅ-waves
  • Q-waves with negative to isoelectric deflections in V1 and in the inferior leads:May suggest a former high lateral MI and right axis deviation
  • May suggest a former high lateral MI and right axis deviation
  • Negative deflecting пїЅ пїЅ-waves
  • QRS complexes in the inferior leads:Often mistaken for prior inferior MI
  • Often mistaken for prior inferior MI
  • Orthodromic atrioventricular re-entrant tachycardia (OAVRT):The pathway that conducts the impulse to the ventricle is the AV node/His " пїЅPurkinje systemNarrow QRS complex tachycardiaHowever, this may be associated with a wide QRS complex in the presence of a pre-existing or rate-related functional bundle branch block.P-wave following the QRSRate between 150 " пїЅ250 bpmThe пїЅ пїЅ-wave seen during sinus rhythm is lost since antegrade conduction is not via the accessory pathway
  • Antidromic AVRT:RegularWide QRS complexThe antegrade limb is usually the accessory pathway.
  • Atrial fibrillation:IrregularWide complex with variable QRS morphologies
  • The pathway that conducts the impulse to the ventricle is the AV node/His " пїЅPurkinje system
  • Narrow QRS complex tachycardia
  • However, this may be associated with a wide QRS complex in the presence of a pre-existing or rate-related functional bundle branch block.
  • P-wave following the QRS
  • Rate between 150 " пїЅ250 bpm
  • The пїЅ пїЅ-wave seen during sinus rhythm is lost since antegrade conduction is not via the accessory pathway
  • Regular
  • Wide QRS complex
  • The antegrade limb is usually the accessory pathway.
  • Irregular
  • Wide complex with variable QRS morphologies

Differential Diagnosis

  • Pre-excitation:Inferior MI
  • Narrow complex supraventricular tachycardias without an accessory pathway:AV nodal re-entry tachycardia (AVNRT)
  • Wide complex tachycardia:Atrial fibrillation with intraventricular conduction delayVentricular tachycardia
  • Inferior MI
  • AV nodal re-entry tachycardia (AVNRT)
  • Atrial fibrillation with intraventricular conduction delay
  • Ventricular tachycardia

Treatment

Pre-Hospital

  • Supplemental oxygen and monitor
  • Vagal maneuvers (Valsalva), carotid massage, and ice water on the face
  • Synchronized cardioversion for:Signs of instability (hypotension, AMS, etc.)Atrial fibrillation with WPW; wide complex tachycardia
  • Pre-hospital use of adenosine:Stable patients: No emergent conversion.Unstable patients: Need cardioversion, not adenosine.
  • Signs of instability (hypotension, AMS, etc.)
  • Atrial fibrillation with WPW; wide complex tachycardia
  • Stable patients: No emergent conversion.
  • Unstable patients: Need cardioversion, not adenosine.

Initial Stabilization/Therapy

  • Unstable patients:Synchronized cardioversion (start with 100 J)Increase incrementally until sinus rhythm is restored (200 J then 360 J).
  • Stable patients with wide complex tachycardia:AmiodaroneProcainamideDO NOT USE: Lidocaine, calcium channel blockers, пїЅ пїЅ-blockers, and Digoxin in patients with wide complex tachycardia and suspected WPW.
  • Synchronized cardioversion (start with 100 J)
  • Increase incrementally until sinus rhythm is restored (200 J then 360 J).
  • Amiodarone
  • Procainamide
  • DO NOT USE: Lidocaine, calcium channel blockers, пїЅ пїЅ-blockers, and Digoxin in patients with wide complex tachycardia and suspected WPW.

Ed Treatment/Procedures

  • Stable patients:Vagal maneuvers: Valsalva and carotid massage:Right carotid artery massage for no more than 10 secAuscultate the artery 1st for a bruit that would contraindicate this procedure.Fluid replacement and Trendelenburg if the patient has mild hypotensionPharmacologic conversion if carotid massage fails
  • Orthodromic (usually narrow complex) AVRT:Adenosine or verapamil
  • Antidromic (usually wide complex) AVRT:Procainamide is the drug of choiceAlthough verapamil and пїЅ пїЅ-blockers can be used when the diagnosis is certain, their administration can be dangerous in ventricular tachycardia and WPW with atrial fibrillation, which can be hard to distinguish from this dysrhythmia.
  • Irregular wide complex tachycardia:WPW syndrome with atrial fibrillationAmiodarone or procainamide.
  • Vagal maneuvers: Valsalva and carotid massage:Right carotid artery massage for no more than 10 secAuscultate the artery 1st for a bruit that would contraindicate this procedure.
  • Fluid replacement and Trendelenburg if the patient has mild hypotension
  • Pharmacologic conversion if carotid massage fails
  • Right carotid artery massage for no more than 10 sec
  • Auscultate the artery 1st for a bruit that would contraindicate this procedure.
  • Adenosine or verapamil
  • Procainamide is the drug of choice
  • Although verapamil and пїЅ пїЅ-blockers can be used when the diagnosis is certain, their administration can be dangerous in ventricular tachycardia and WPW with atrial fibrillation, which can be hard to distinguish from this dysrhythmia.
  • WPW syndrome with atrial fibrillation
  • Amiodarone or procainamide.
  • Children may develop ventricular rates up to 320 bpm that are poorly tolerated.
  • Cardiovert unstable children with 0.5 " пїЅ2 J/kg.
  • Vagal maneuvers and adenosine are safe in stable children.

Medication

  • Adenosine: 6 mg rapid IV bolus over 1 " пїЅ2 sec; if ineffective, repeat with 12 mg (peds: 0.1 mg/kg rapid IV push, repeat with 0.2 mg/kg)
  • Amiodarone: 150 mg IV over 10 min, 360 mg over the next 6 hr
  • Magnesium: 2 g IV bolus
  • Procainamide: 6 " пїЅ13 mg/kg IV at 0.2 " пїЅ0.5 mg/kg/min until either arrhythmia controlled, QRS widens 50%, or hypotension, then 2 " пїЅ6 mg/min, max. of 1,000 mg
  • Amiodarone for wide complex tachycardias
  • Adenosine for narrow complex tachycardias
  • Procainamide for wide complex tachycardias
  • IV Procainamide, IV Verapamil 5 " пїЅ10 mg, IV Diltiazem 10 " пїЅ20 mg, or Esmolol can be considered as 2nd-line agents for patients with WPW presenting with regular narrow complex tachycardias.

Follow-Up

Disposition

  • Signs of instability and/or history of syncope
  • Failure of outpatient therapy for continuous pharmacologic control or ablation
  • Most patients will be stable and can be discharged once converted to sinus rhythm
  • Follow-up should be arranged with a cardiologist

Followup Recommendations

  • Palpitations
  • Dizziness
  • Chest pain
  • Feeling faint or actual syncope

Pearls and Pitfalls

  • These medications prolong the refractory period of the AV node, increasing the rate of transmission through the accessory pathway, and may result in fatal ventricular dysrhythmias.
  • If symptoms >48 hr, anticoagulation must be addressed prior to cardioversion as 1 " пїЅ3% of patients will have embolic event. Transesophogeal echo should be considered to rule out left atrial thrombus.

Additional Reading

  • Keating пїЅ пїЅL, Morris пїЅ пїЅFP, Brady пїЅ пїЅWJ. Electrocardiographic features of Wolff-Parkinson-White syndrome. Emerg Med J. 2003;20(5):491 " пїЅ493.
  • Mark пїЅ пїЅDG, Brady пїЅ пїЅWJ, Pines пїЅ пїЅJM. Preexcitation syndrome: Diagnostic considerations in the ED. Am J Emerg Med. 2009;27:878 " пїЅ888.
  • Schwieler пїЅ пїЅJH, Zlochiver пїЅ пїЅS, Pandit пїЅ пїЅSV, et al. Reentry in an accessory atrioventricular pathway as a trigger for atrial fibrillation initiation in manifest Woff-Parkinson-White syndrome: A matter of reflection? Heart Rhythm. 2008;5(9):1238 " пїЅ1247.
  • Simonian пїЅ пїЅSM, Lotfipour пїЅ пїЅS, Wall пїЅ пїЅC, et al. Challenging the superiority of amiodarone for rate control in Wolff-Parkinson-White and atrial fibrillation. Intern Emerg Med. 2010;5(5):421 " пїЅ426.

Codes

ICD9

ICD10

SNOMED

  • 74390002 Wolff-Parkinson-White pattern (disorder)