WPW
Background
- Congenital, abN, faster "accessory" path bypassing normal delay at AVN
- In sinus impulses reach ventricles via both, so delta (Δ) wave
- Accesory path faster (short P-R interval)
- QRS (>120ms) & T wave changes because not "normal" purkinje conduction
- Potential for "circular" impulses up/down via AVN or accessory path
Clinical
- Noted on "routine" ECG
- May present as SVT or AF
- Presents as "SVT" in children
- Implicated in some VF arrest
- Occasionally ppt as chest pain
Differential Dx
- AF / flutter /AT
- AVNRT
- Structural anbormality (Ebstein)
- Lown-Ganong-Levine syndrome (no delta wave)
- VT
ECG
Asymptomatic
- Short PR (<120ms)
- T wave abnormalities
- Dominant R in V1 (± V2)
- Inf. Q (non-pathological)
Types
- Type A – tall R in V1, LAD
- Type B – deep S in V1, LAD
- Type C – tall R in V1, axis – 90°
Symptomatic
- AF = risk of VF
- AVRT
- Most no Δ wave as "down" AVN and up accessory
- Some wide QRS tachy (down accessory and back via AVN)
Management
- Unwell → synchronised DC shock (100J)
- Well: try vagal manouvres ()
- Adenosine (if narrow complex)
- Stable → slow the accessory pathway (use: sotalol, amiodarone, flecanide)
Avoid
- No Digoxin (decreases refractory period)
- No verapamil (increases vent. rate)
- Β-blockers (no effect on accessory path)
Content by Dr Íomhar O' Sullivan. Last review Dr ÍOS 11/04/23.