Slow Pathway Ablation for Atrioventricular Nodal Reentrant Tachycardia

Combination of both electrogram (targeting Asp potential) and anatomical approach is generally accepted as ablation of antegrade slow pathway for slow/fast and slow/slow atrioventricular nodal reentrant tachycardia (AVNRT). Ablation of retrograde slow pathway is performed at the site recording the retrograde Asp potential or the earliest atrial activation during tachycardia and ventricular pacing for fast/slow and slow/slow AVNRT. Differentiating slow/slow AVNRT from slow/fast AVNRT before ablation is important, since the recurrence rate after slow pathway ablation in slow/slow AVNRT is much greater than slow/fast AVNRT. In rare cases in which an extensive ablation at sites posteroseptal right atrium between the tricuspid annulus and the coronary sinus ostium as well as inside the proximal coronary sinus is unsuccessful, the leftward posterior extension of the atrioventricular node may play a role as the slow pathway for AVNRT. An ablation at deep inside the coronary sinus ≥3 cm from the ostium or at the mitral annulus may be required in these cases.