Multiple patterns of ventiruclar preexcitation in a patient with two left accessory pathways

pp 407-410

Abstract

The coexistence of two AV accessory pathways conducting in anterograde direction may res­ult in two activation fronts which depolarize both ventricles simultaneously and generate fusion QRS complexes. This situation may cons­pire against the electrocardiographic identifi­cation of the anatomic localization of the A V by-pass tracts. A patient suffering form recu­rrent episodes of paroxysmal supraventricular tachycardia showed multiple patterns of ventricular preexcitation due to the presence of two left sided A V accessory pathways (ante­rolateral and posteroseptal) with predominant propagation by one of them, fusion beats and alternating conduction due to 2:1 block in both anomalous bundles.