Methods and apparatus for an ablation device used in the treatment of atrial fibrillation comprise an elongate shaft and a positioning mechanism adjacent the distal end of the shaft. The positioning mechanism is adapted to facilitate location of an anatomic structure and also to anchor the elongate shaft adjacent the anatomic structure. The positioning mechanism comprises an electrode for stimulating the anatomic structure as well as sensing electrical signals. Also, an energy delivery element is adjacent the distal end of the shaft and is adapted to stimulate the anatomic structure and create a zone of ablation that blocks abnormal electrical activity thereby reducing or eliminating atrial fibrillation in the patient.