Wolff-Parkinson-White (WPW) syndrome
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Etiology
- accessory tract bypassing AV node, generally congenital
- generally no underlying heart disease
- clinical associations
Epidemiology
- incidence of accessory pathway is 0.3% in the general population
Pathology
- pre-excitation & paroxysmal supraventricular tachycardia (PSVT)
- an accessory bypass tract sets up a circuit which allows either:
- orthodromic conduction through the AV node with retrograde conduction through the accessory pathway (orthodromic PSVT)*
- anterograde conduction through the accessory pathway with retrograde conduction through the AV node (antidromic PSVT)*
- accessory path may be intermittently anterograde or retrograde
- tachycardia develops in 70% of these patients
- the tachycardia is due to atrioventricular reentrant tachycardia**
- increased tendency towards atrial fibrillation
- combined atrial fibrillation & ventricular pre-excitation (i.e. anterograde conduction through the accessory pathway) may predispose patients to ventricular fibrillation
* Also orthodromic & antidromic reciprocating tachycardia. ** a delta wave makes atrioventricular nodal reentrant tachycardia unlikely
Diagnostic procedures
- electrocardiogram:
- ventricular pre-excitation (delta wave)*
- due to anterograde conduction through the accessory pathway
- patients with accessory pathways that conduct only in the retrograde direction do NOT have a pre-excitation delta wave
- pre-excitation may be enhanced by slowing conduction through the AV node
- carotid sinus massage
- vagal maneuvers
- short-acting AV nodal blocking agents
- pre-excitation may resolve with exercise (low risk)
- short PR interval (< 120 msec)*
- wide QRS complex (> 120 msec)*
- paroxysmal supraventricular tachycardia (PSVT)*
- may be Q-wave in V1-V3
- may be R in V1
- ST & T wave changes opposite in polarity to QRS complex
- wide complex tachycardias
- orthodromic tachycardia with bundle-branch block
- antidromic tachycardia
- inverted p-wave prior to every QRS
- short, but constant PR interval
- no isoelectric PR segment
- wide & bizarre QRS morphology
- may resemble ventricular tachycardia
- atrial fibrillation
- atrial flutter
- narrow complex tachycardia (most common)
- orthodromic conduction in the absence of bundle-branch block
- orthodromic PSVT (AV reentrant tachycardia/AV reciprocating tachycardia) with normal QRS (no pre-excitation)#
- ventricular pre-excitation (delta wave)*
- exercise stress testing prior to participation in competitive sports
- normalization of the QRS complex during exercise indicates low risk for sudden cardiac arrest[6]
- electrophysiology
- asymptomatic patients with WPW in sinus rhythm do not necessarily require electrophysiology studies
- if QRS complex does not normalize during exercise stress testing
- symptomatic &/or high-risk of sudden cardiac death
* defining criteria for WPW
# AV nodal reentrant tachycardia is caused by dual nodal AV physiology not WPW[7]
Complications
- atrial fibrillation can convert to ventricular fibrillation
Management
- acute episodes are managed similar to AVNRT
- vagal maneuvers
- AV nodal blocking agents (short-acting) *see below*
- adenosine may potentiate short periods of atrial fibrillation
- DC cardioversion should be available
- cardioversion for any unstable patient
- wide complex tachycardia
- lidocaine may precipitate ventricular tachycardia
- synchronized cardioversion is hemodynamically unstable
- procainamide agent of choie in hemodynamically stable patient
- atrial fibrillation
- AV blocking agents contraindicated
- Ca+2-channel antagonists, beta-blockers, digoxin
- will NOT prevent & may precipitate a rapid ventricular response to atrial fibrillation if anterograde conduction occurs through accessory pathway.
- use class Ia, Ic & III anti-arrhythmic agents[4]
- class Ia anti-arrhythmic agents
- quinidine, procainamide
- intravenous procainamide (drug of choice); up to 15 mg/kg IV at 25-50 mg/min; monitor BP every 5 min
- quinidine, procainamide
- class Ic anti-arrhythmic agents
- class III anti-arrhythmic agents
- class Ia anti-arrhythmic agents
- cardioversion if hemodynamic compromise
- AV blocking agents contraindicated
- chronic therapy
- class Ia, Ic & III anti-arrhythmic agents (2nd line therapy)[4]
- slows conduction in accessory pathway
- procainamide (preferred agent in pregnancy)
- flecainide
- if NO atrial fibrillation
- class Ia, Ic & III anti-arrhythmic agents (2nd line therapy)[4]
- electrophysiologic testing
- symptomatic patients
- asymptomatic patients in high-risk occupations
- radio frequency catheter ablation of accessory tract for symptomatic AVNRT
- curative, 1st line therapy[4]
- indications
- drug resistant tachycardia
- patients who do not wish to take long-term drugs
- 1st line therapy[4]
- contraindications:
- avoid during pregnancy, radiation exposure of fluoroscopy
More general terms
Additional terms
- atrial fibrillation (AF)
- AV nodal re-entrant tachycardia (AVNRT)
- Ebstein's anomaly
- paroxysmal supraventricular tachycardia (PSVT)
- pre-excitation
References
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 145
- ↑ Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 274
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 77-79
- ↑ 4.0 4.1 4.2 4.3 4.4 Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2006, 2009, 2015, 2018, 2022.
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1032
- ↑ 6.0 6.1 Rao AL, Salerno JC, Asif IM, Drezner JA. Evaluation and management of wolff-Parkinson-white in athletes. Sports Health. 2014 Jul;6(4):326-32. PMID: https://www.ncbi.nlm.nih.gov/pubmed/24982705 PMCID: PMC4065555 Free PMC article
- ↑ 7.0 7.1 NEJM Knowledge+
Link MS Clinical practice. Evaluation and initial treatment of supraventricular tachycardia. N Engl J Med. 2012 Oct 11;367(15):1438-48 PMID: 23050527 https://www.nejm.org/doi/pdf/10.1056/NEJMcp1111259 Review.