An atriofascicular tract in a girl with Ebstein's anomaly and right bundle block

Described in this article is a clinical case of a 14-year girl with Ebstein's anomaly and a complex preexitation syndrome (two atrioventricular pathways and a true atriofascicular Mahaim's tract). The atriofascicular tract was involved in antidromic and orthodromic tachycardias. The Л-wave was absent initially, because the spontaneous right bundle block and the comparable AV conduction velocity imitated a normal sinus rhythm. All accessory pathways were eliminated successfully during catheter ablation.