New Insights into Reentry Circuits from Mapping and Ablation of Atrioventricular Nodal Reentrant Tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is a very common cardiac arrhythmia and is due to reentry within the region of the atrioventricular junction. The anatomy of the atrioventricular (AV) node, including inferior extensions within the triangle of Koch and a transitional zone of cells interposed between the compact node and atrial myocardial cells, has been extensively investigated. The functional inputs to the AV node have been revealed to be multiple, from both sides of the interatrial septum. Despite this knowledge the precise nature of the reentry circuit and its variants remains elusive, with a variety of proposed models. Regardless, catheter ablation of the slowly conducting pathway inferior to the compact node, within the triangle of Koch or anterior to the ostium of the coronary sinus, is a highly effective method by which the circuit can be disrupted and AVNRT eliminated.