Ablation of Atrioventricular Junctional Tachycardias: Atrioventricular Nodal Reentry, Variants, and Focal Junctional Tachycardia

Atrioventricular nodal reentrant tachycardia (AVRNT) is the most common form of regular supraventricular tachycardia. Although the anatomy and histology of the AV node and its relationship with nearby atrial structures and with the His bundle were well described in great detail by Tawara more than a century ago, it is still erroneously described as a right sided structure. Inputs to the AV node proceed from the right and left atria and are involved in the different forms of AVNRT. Dual AV nodal physiology is a normal behavior of the human AV node that can be observed in around 85% of normal individuals and should not be used as a surrogate of inducible AVNRT. Finally, the coexistence of AVNRT with other arrhythmias in patients without obvious heart disease suggests the possibility of an underlying developmental abnormality of the cells originating from the neural crest (MV Elizari, personal communication). Most patients with AVNRT have no evidence of structural heart disease, although it also occurs in patients with congenital and acquired heart disease. In some patients AVNRT has a benign course, but in others it can also result in disabling symptoms, especially in elderly patients in whom syncope may be the initial presentation. Although catheter ablation can eliminate the tachycardia in most patients, the reentrant paths supporting this tachycardia can vary significantly in different patients. Therefore different forms of AVNRT are now well recognized and are better described by the pathways involved in the reentry. Slow-fast AVNRT is the most common (~80%), followed by slow-slow AVNRT and fast-slow AVNRT. More than one form may be observed in a given patient. Catheter ablation with elimination of 1:1 antegrade and/or retrograde conduction over the slow AV nodal pathway is a highly successful treatment of AVNRT with a low risk of complications.