Transmural Ablation From the Mitral Annulus to the Left Lower Pulmonary Vein≠Mitral Isthmus Block

Great teaching value can come from showcasing an unusual phenomenon that serves as an aid to explain how best to approach mundane, common problems. In this installment of teaching rounds, Wakabayashi et al use an unusual activation sequence observed along the mitral annular atrial myocardium that was observed after ablation of the mitral isthmus to teach us about the pitfalls created by the complex terrain in the left atrium (LA).