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Wolff–Parkinson–White syndrome
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.
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Wolff–Parkinson–White syndrome
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- 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
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- 5. •…and as itgets to the Purkinje fibers, next is the endocardium at the apex of the heart, then finally to the ventricular myocardium.
- 6. Atrioventricular node. The AVnode serves an important function • limiting the electrical activity that reaches the ventricles. • it slows down individual electrical impulses. (the PR interval)
- 7. However…. • Individuals withWPW 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 ofKent
- 9. This pathway maycommunicate 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 • ShortPR 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 CardiacActivation 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
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- 15. ORTHODROMIC • DESCEND- NORMALPATHWAY • 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 COMMONPATHWAY. • 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’ conductionpathway 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 (LGLSYNDROME) • 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 • Syncopalattacks • Sudden cardiac death • Complications of drug therapy (eg, proarrhythmia, organ toxicity) • Complications associated with invasive procedures and surgery • Recurrence
- 22. Treatment • People withatrial 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 betaken 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)
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