Wolff Parkinson White (WPW) syndrome and atrial fibrillation

See brief interpretation of EKG tracing above

- only the 6 limb leads are shown
- rapid, irregular, broad complex tachycardia with bizarre complexes and occasional narrow complexes
- impression of delta waves in QRS complexes

In atrial fibrillation, rapid conduction of atrial impulses to the ventricles are prevented by the atrioventricular (AV) node. The AV node is capable of decremental conduction – that is the faster it is stimulated, the slower it conducts.

However, in Wolff Parkinson White syndrome the accessory conduction pathway provides an alternative conduction route from the atria to the ventricles. Thus rapid conduction of atrial impulses to the ventricles are possible (ventricular pre-excitation).

The resulting EKG shows a fast ventricular rate – often more than 200 beats per minute. The rhythm is completely irregular. The QRS complexes are a result of conduction through the accessory bundle, the AV node or both. Most are broad and look bizarre with an impression of delta waves. Occasionally narrow complexes are seen.

There is an increased risk of progression into ventricular fibrillation and sudden death.

In sinus rhythm the characteristic delta waves and the short PQ intervals are clearly seen:

About 1/3 of patients with Wolff Parkinson White syndrome develop episodes of atrial fibrillation.

– Mathias