Ablation Options and Anatomical Challenges
The mitral isthmus traditionally refers to the left atrial region between the mitral valve annulus and the anterior aspect of the left inferior pulmonary vein (LIPV). However, there are, in fact, multiple isthmuses to which ablative therapy may be applied to interrupt the flutter circuit as it circumnavigates the mitral annulus, each associated with different anatomical advantages and challenges. These ablation lines are defined as follows (see Figure 1):