Where is the AVNRT mapping target located?

• A. Triangle of Koch, low septal RA
• B. Right atrial appendage
• C. Left atrial appendage
• D. Right ventricle free wall

Answer: (A)

In AVNRT, the reentrant circuit relies on dual AV nodal pathways that come together near the AV node. The mapping target for interrupting this circuit is located in the posterior, inferior area of the AV nodal region—the low septal right atrium inside Koch’s triangle, close to the coronary sinus ostium. The AV node sits at the apex of Koch’s triangle, so ablation is aimed at the slow-pathway region there to disrupt the reentry circuit without injuring the fast pathway.

That’s why the correct site is the triangle of Koch in the low septal right atrium. The other structures—the right atrial appendage, left atrial appendage, or right ventricular free wall—do not participate in the AV nodal dual-pathway mechanism and are not typical targets for AVNRT mapping.