Focal atrial tachycardia from the fossa ovalis in a patient with Bachmann's bundle block.

We report the case of a patient with tracings during sinus rhythm compatible with block of the Bachmann's bundle and presenting with focal atrial tachycardia arising from the fossa ovalis with successful ablation on the right side of the septum. Upward activation of the left atrium has been related in this case to the block of the Bachmann's bundle and to the lack of transseptal conduction.