Bachmann's bundle and upper septal inter-atrial connections as key paths for a biatrial macro re-entrant circle: a case report.

Background: The Bachmann's bundle has been described as a key route for re-entrant circuits in biatrial tachycardias. Septal inter-atrial muscular connections were discovered a while ago, but evidence on their potential role in re-entrant tachycardias is lacking.

Case Summary: We describe an atrial macro re-entrant circuit presented as a wide complex tachycardia that utilized the Bachmann's bundle, septal inter-atrial connections, and a limited area of the anterior left atrial myocardium in a patient with previous multiple atrial fibrillation ablation procedures. This tachycardia was diagnosed by using a combination of electrophysiological visualization modalities and was terminated by a single radiofrequency application.

Discussion: The inter-atrial muscular connections can pose a major contribution to the mechanism of biatrial tachycardias, especially in patients after extensive left atrial ablation. Thorough mapping modalities, including entrainment stimulation, facilitate a correct diagnosis. Understanding inter-atrial connection anatomy is crucial for the detection and successful ablation of such tachycardia.