Figure 3a

Atrial fibrillation in WPW syndrome with accessory pathway conduction.
Left:Sinus rhythm with a typical preexcitation pattern.
Right:Accessory pathway conduction during atrial fibrillation.The QRS has shifted to the left,and the ventricular rhythm is now irregular at a rate in excess of 200 per minute.

(HJL Marriott, HM Rogers: Mimics of ventricular tachycardia associated with the WPW syndrome. J ELECTRCARDIOL. 2,: 77,1969)