Wolff–Parkinson–White syndrome

Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals traveling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supra-ventricular tachycardia referred to as an atrio-ventricular reciprocating tachycardia.

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 m ore than one accessory pathway. The most common accessory pathway is known as the B undle 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-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

11. 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

12. PATHWAY

13. 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

14. 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

15. 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

16. 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)

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

18. 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.

19. Caution should be taken in regards to… Possibility of Sudden C ardiac 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 m ore than one accessory pathway)

20. I appreciate your attention . Adighibenma S.O.S