PREEXCITATION (Wolf's parkinsinson white) SYNDROME

PREEXCITATION (WPW) SYNDROME

1. most frequently encountered type of ventricular preexcitation is that associated with AV bypass tracts
2. the most common bypass tract is an accessory atrioventricular (AV) pathway otherwise known as a Kent bundle. This is the anomaly seen in WPW syndrome. Conduction through a Kent bundle can be anterograde, retrograde, or both
3. Lown-Ganong-Levine (LGL), also has an accessory pathway (the James fibers), which connect the atria serially to the His bundle
4. The term Wolff-Parkinson-White syndrome is applied to patients with both preexcitation on the ECG and paroxysmal tachycardias. AV bypass tracts can be associated with certain congenital abnormalities, the most important of which is Ebstein's anomaly.
5. Men (60-70% cases) are affected more often than women
6. Age: Although this disease affects people of all ages, it is most commonly recognized in children and young adults presenting to the ED with a dysrhythmia. Conduction speed in the accessory pathway appears to attenuate with age.
7. Type A WPW syndrome is described as having an upright positive delta wave in all precordial leads with a resultant R greater than S amplitude in lead V1.
8. Type B has a predominantly negative delta wave and QRS complex in leads V1 and V2 and becomes positive in transition to the lateral leads resembling that of a left bundle-branch block
9. AV bypass tracts that conduct in an antegrade direction produce a typical ECG pattern of a short PR interval (<0.12>
10. LGL has a shortened PR interval due to the presence of the accessory pathway bypassing the AVN, but a normal QRS because the accessory pathway (James fibers) connects directly with the His bundle and do not depolarize the ventricles directly but do so through the typical conduction pathway through the His-Purkinje system.
11. Ecg findings

a short PR interval (0.11 s),

a wide QRS complex (0.12 s),

slurring on the upstroke of the QRS : delta wav