What is the mapping strategy of AVNRT?

• A. Anatomical approach, Triangle of Koch, low septal RA
• B. Activation mapping in Right Ventricular Outflow Tract
• C. Left atrial appendage mapping
• D. Epicardial mapping of the left ventricle

Answer: (A)

AVNRT relies on dual AV nodal pathways forming a reentrant loop around the AV node. The practical way to disrupt this loop is an anatomical approach that targets the slow conduction tissue in the right atrium, specifically in the posteroinferior region within the triangle of Koch. The triangle of Koch, bounded by the tendon of Todaro, the ostium of the coronary sinus, and the tricuspid annulus, houses the AV node and the slow pathway. Ablation is delivered near the ostium of the coronary sinus in this area to modify or eliminate the slow pathway while avoiding damage to the compact AV node, reducing the likelihood of AV block.

Other mapping strategies aren’t used for AVNRT because they focus on different substrates or chambers: activation mapping in the RVOT targets ventricular tachycardias from that outflow tract; left atrial appendage mapping is for atrial arrhythmias involving the left atrium; epicardial mapping of the left ventricle is for epicardial substrates in VT.