Which structure is the typical ablation target for AVNRT?

Which structure is the typical ablation target for AVNRT?

• A. Triangle of Koch
• B. Bundle of His
• C. Mitral Annulus
• D. Crista Terminalis

Answer: (A)

In AVNRT the arrhythmia uses a slow pathway located in the region around the AV node. The typical ablation target is the slow pathway tissue within Koch's triangle, the right atrial area bounded by the tricuspid annulus, the tendon of Todaro, and the ostium of the coronary sinus, where the AV node resides. By applying energy there, the slow conduction pathway is modified or eliminated, breaking the reentrant circuit while preserving the essential AV conduction through the compact node. The Bundle of His is part of the main conduction system; ablating there risks causing complete AV block, which is not desirable. The Mitral Annulus is a left-sided structure unrelated to the AVNRT circuit, and the Crista Terminalis is a muscle ridge serving as a landmark rather than the substrate for this tachycardia.

In AVNRT the arrhythmia uses a slow pathway located in the region around the AV node. The typical ablation target is the slow pathway tissue within Koch's triangle, the right atrial area bounded by the tricuspid annulus, the tendon of Todaro, and the ostium of the coronary sinus, where the AV node resides. By applying energy there, the slow conduction pathway is modified or eliminated, breaking the reentrant circuit while preserving the essential AV conduction through the compact node.

The Bundle of His is part of the main conduction system; ablating there risks causing complete AV block, which is not desirable. The Mitral Annulus is a left-sided structure unrelated to the AVNRT circuit, and the Crista Terminalis is a muscle ridge serving as a landmark rather than the substrate for this tachycardia.