Inapparent atrial flutter due to atrial dissociation.

Percutaneous and surgical procedures intended to potentially cure atrial fibrillation require creating lines of conduction block in specific locations throughout the atrial chambers. In patients presenting with recurrent atrial fibrillation, repeat procedures are often performed, resulting in more extensive regions of conduction block and the potential for regions of dissociated atrial rhythms. The present case describes a patient post-multiple ablation procedures who presented with a symptomatic atrial arrhythmia, the mechanism of which was hidden by the presence of extensive atrial dissociation. Electrophysiologic study revealed the appropriate mechanism and a beneficial ablative procedure was then successfully accomplished.