Atrial Fibrillation and Wolff-Parkinson-White Syndrome (WPW)

In Wolff-Parkinson-White syndrome, antegrade conduction occurs over an accessory pathway. If atrial fibrillation, develops this is a medical emergency because very rapid ventricular rates can develop.

(See also Overview of Arrhythmias and Atrial Fibrillation.)

In manifest Wolff-Parkinson-White (WPW) syndrome, antegrade conduction occurs over the accessory pathway. If atrial fibrillation develops, the normal rate-limiting effects of the atrioventricular (AV) node are bypassed, and the resultant excessive ventricular rates (sometimes 200 to 300 beats/minutes) may lead to ventricular fibrillation (see figure Atrial Fibrillation in Wolff-Parkinson-White syndrome) and sudden death (1).

Patients with an accessory AV connection that does not conduct in the antegrade direction do not have the short PR interval and delta wave characteristic of WPW syndrome (concealed WPW syndrome). However, they may still have orthodromic reciprocating atrioventricular supraventricular tachycardia, in which the accessory AV connection is used in the retrograde direction, but they are not at risk of rapid conduction of atrial fibrillation, in which the accessory AV connection is used in the antegrade direction).

Atrial Fibrillation in Wolff-Parkinson-White Syndrome

Ventricular response is very fast (RR intervals minimum of 160 msec). Shortly thereafter, ventricular fibrillation develops (lead II continuous rhythm strip at bottom).