Successful Zero-Fluoroscopy Ablation of an Atypical Clockwise Simple-Loop Biatrial Flutter Involving the Bachmann Bundle Region.

A 69-year-old woman presented with an atypical clockwise simple-loop biatrial flutter as a consequence of an anterior mitral line ablation for perimitral atrial flutter. Local activation mapping and entrainment maneuvers helped define the circuit, highlighting a critical epicardial connection through the Bachmann bundle region. Successful radiofrequency ablation was performed at the left lateral atrial insertion of the Bachmann bundle. Deep knowledge of anatomy and epicardial bridging and careful analysis of the entrainment maneuvers, along with local activation time mapping, are critical to defining a successful ablation strategy.