Fig. 2

The delineation of the mechanism of preexcitation syndrome with overt accessory pathway. (a) The activation prematurely depolarizes the ventricle via accessory pathway which is faster than AV node, forming the delta wave. (b) The onset of the normal atrioventricular node conduction is the termination of the delta wave, but the accessory pathway conduction is continuous. (c) The activation simultaneously conducts through the accessory pathway and normal conduction system, fusing into the monophyletic ventricular fusion with delta wave in its initiation and the deformation in its termination