Wolff-Parkinson-White (WPW) Syndrome
- Congenital accessory cardiac conduction pathway (Bundle of
Kent)
- Pre-excitation (early depolarization) of the ventricles via
this
pathway bypasses the AV Node and can predipose to potentially
fatal
tachyarrhythmia
- Conduction can be orthodromic, antidromic, or both (majority)
- ORTHODROMIC (down the AV-node and up accessory pathway to
re-enter AV-node)
- ANTIDROMIC (down accessory pathway and up AV-node pathway to
re-enter accessory pathway)
- Incidence: 0.1 – 3.0 per 1000
EKG Findings
- Short PR interval (<0.12) – because no AV conduction
delay!!!
-
QRS > 0.1 (Widened QRS interval) - the delta wave can come
and go!!!
-
Delta wave (slurred QRS)
- "Pseudo-infarction pattern (up to 70% of patients) due to
negatively deflected delta waves in the inferior / anterior
leads
(“pseudo-Q waves”), or as a prominent R wave in V1-3 (mimicking
posterior infarction)" [LIFL]
Afib with WPW
- Irregular, wide complex tachycardia with changing QRS
morphologies
-
Rates approach 300
-
DO NOT give adenosine or amiodarone or verapamil (AV-nodal
blockers) because can induce VFib
-
Procainamide or cardioversion and then ablation
Treatment
- Avoid A-B-C-D (Adenosine, Beta blockers, CCB, Digoxin)
- Use procainamide (17 mg/kg over 1 hour) or cardioversion
- In the past - Amiodarone - now NOT
recommended ("IV amiodarone,
adenosine, digoxin, or nondihydropyridine calcium channel
antagonists
in patients with WPW syndrome who have pre-excited AF is
potentially
harmful")
SVT with WPW
- ORTHODROMIC - antegrade down AV-node and up accessory pathway
to re-enter AV-node
-
80-90% of SVT's are orthodromic
-
Creates narrow complex, regular tachycardia with rates of
200-300
-
Ok to treat with any AV-nodal blocker (adenosine, BB, CCB)
-
ANTIDROMIC - down accessory pathway and up AV-node pathway to
re-enter accessory
- Creates wide, regular tachycardia (amiodarone, procainamide)
with rates of 200-300
A 21-Year-Old Man with Syncope and Palpitations
Tachydysrhythmia
Differential Diagnosis
WPW Lecture
Reference: Topics in Emergency Medicine 2010. CAN’T MISS ECG
FINDINGS. L. THOMAS RICHARDS, MD. UCSF.
Reference:
http://lifeinthefastlane.com/ecg-library/pre-excitation-syndromes/