Wolff-Parkinson-White syndrome is caused by an abnormal accessory electrical pathway between the atria and ventricles that can bypass the AV node and allow rapid conduction, potentially causing palpitations, dizziness and other symptoms; the condition is usually asymptomatic but can cause tachyarrhythmias due to orthodromic or antidromic conduction along the accessory pathway; treatment involves catheter ablation to destroy the accessory pathway or medications to control the heart rate during arrhythmias.

1. Wolff–Parkinson–White
syndrome

2. Introduction
• Wolff–Parkinson–White syndrome (WPW) a pre-
excitation syndrome is caused by the presence of an
abnormal accessory electrical conduction pathway
between the atria and the ventricles.
• This is often congenital

3. Signs and Symptoms
• People with WPW are usually asymptomatic. However, the
individual may experience
• palpitations,
• dizziness,
• shortness of breath,
• syncope
• sweating

4. Pathophysiology

5. •…and as it gets to the Purkinje
fibers, next is the endocardium
at the apex of the heart, then
finally to the ventricular
myocardium.

6. Atrioventricular node.
The AV node serves an important function
• limiting the electrical activity that reaches the
ventricles.
• it slows down individual electrical impulses. (the PR
interval)

7. However….
• Individuals with WPW have an accessory pathway that
communicates between the atria and the ventricles, in addition
to the AV node. This pathway forms a bypass which enables
supraventricular impulse to bypass AV node , bundle of HIS and
distal conducting system and so activate or pre excite the
ventricles. An Individual could have more than one accessory
pathway.
• The most common accessory pathway is known as the Bundle of Kent
• This accessory pathway does not share the rate-slowing
properties of the AV node, and may conduct electrical activity at a
significantly higher rate than the AV node.

8. …with Bundle of Kent

9. This pathway may communicate between
the left atrium and the left ventricle, in which case it is termed a "type A pre-
excitation"
or
the right atrium and the right ventricle, in which case it is termed a "type B pre-
pre-excitation".
Problems arise when this pathway creates an electrical circuit that bypasses the AV
node. When an aberrant electrical connection is made via the bundle of Kent,
tachydysrhythmias may therefore result.

10. ECG Presentation
• Short PR interval
• Slurred initial upstroke of QRS – delta wave
• Relatively normal , narrow terminal QRS –main QRS
deflection
• Slight widening of QRS
• Secondary STT changes

12. Phases of Cardiac Activation
PHASE 1
• Atrial activation- normal
PHASE 2
• Ventricular pre-excitation
• sinus activation occurs through both normal , anomalous pathway
• anomalous pathway lacks AV nodal conduction delay
• so sinus impulse conducted at a rapid rate
• this enables ventricles to be activated or pre exited- short PR interval , delta wave
• Further activation through normal pathway
PHASE 3
• Narrow terminal QRS

14. PATHWAY

15. ORTHODROMIC
• DESCEND- NORMAL PATHWAY
• ASCEND- ACCESSORY PATHWAY
• In orthodromic tachycardia, the normal pathway is used for
ventricular depolarization and the accessory tract is used for reentry.
• Ventricular Premature Contractions can initiate orthodromic
tachycardia
• On ECG findings,
• the delta wave is absent,
• QRS complex is normal,
• P waves are inverted in the inferior and lateral leads

17. ANTIDROMIC
• LESS COMMON PATHWAY.
• DESCEND- ACCESSORY PATHWAY.
• ASCEND – NORMAL PATHWAY
• On ECG findings,
• the QRS is wide, which is an exaggeration of the delta wave during sinus
rhythm (i.e, wide-QRS tachycardia).
• Such tachycardias are difficult to differentiate from ventricular tachycardia

19. The ‘accessory’ conduction pathway fibers
Other than the Kent Fibers (Atrio-Ventricular) previously discussed…
MAHAIM FIBRE:
• Origin- distal to AV node (Hiso-Ventricular)
• Ends in the ventricular myocardium
ECG:
• normal PR interval
• delta waves

20. JAMES FIBRE (LGL SYNDROME)
• Origin- atria (Atrio- His)
• Bypass AV node
• Ends in bundle of HIS
ECG:
• Short PR
• Normal QRS (AV node function is still retained)

21. Complications
• Tachyarrhythmia
• Syncopal attacks
• Sudden cardiac death
• Complications of drug therapy (eg, proarrhythmia, organ toxicity)
• Complications associated with invasive procedures and surgery
• Recurrence

22. Treatment
• People with atrial fibrillation and rapid ventricular response are
often treated with procainamide or amiodarone (rarely). This is to
stabilize their heart rate
• The definitive treatment of WPW is a destruction of the abnormal
electrical pathway by radiofrequency catheter ablation.

23. Caution should be taken in regards to…
• Possibility of Sudden Cardiac death
• AV node blockers should be avoided in atrial fibrillation and atrial flutter
with WPW or history of it; this includes adenosine, digoxin, diltiazem,
verapamil, other calcium channel blockers and beta blockers. They can
exacerbate the syndrome by blocking the heart's normal electrical pathway
• Underlying Ebstein’s anomaly, hypertrophic cardiomyopathy should be
evaluated (In cases of more than one accessory pathway)

24. Iappreciateyour attention.
Adighibenma S.O.S