www.ipej.org 152 Review Article A Review of Mitral Isthmus Ablation

Mitral isthmus ablation forms part of the electrophysiologist’s armoury in the catheter ablation treatment of atrial fibrillation. It is well recognised however, that mitral isthmus ablation is technically challenging and incomplete ablation may be pro-arrhythmic, leading some to question its role. This article first reviews the evidence for the use of adjunctive mitral isthmus ablation and its association with the development of macroreentrant perimitral flutter. It then describes the practical techniques of mitral isthmus ablation, with particular emphasis on the assessment of bi-directional mitral isthmus block. The anatomy of the mitral isthmus is also discussed in order to understand the possible obstacles to successful ablation. Finally, novel techniques which may facilitate mitral isthmus ablation are reviewed. Key words: mitral isthmus; atrial fibrillation; ablation Background Based on the multiple wavelet hypothesis, the Cox-maze procedure was designed using linear lesions to compartmentalize the atria and to interrupt potential macroreentrant circuits which may maintain atrial fibrillation (AF) [1]. Interventional electrophysiologists have subsequently emulated the surgical technique by attempting to perform radiofrequency linear ablation wit