The Triangle of Koch is a landmark within which heart chamber?

• A. Left atrium
• B. Right ventricle
• C. Interventricular septum
• D. Right atrium

Answer: (D)

This landmark sits in the right atrium and marks the location of the AV node. It’s a triangular region bounded by the opening of the coronary sinus, the tendon of Todaro, and the septal leaflet of the tricuspid valve. The AV node lies at the inferior part of this triangle near the interatrial septum, so identifying Koch’s triangle helps locate the node. This is clinically important in electrophysiology and conduction disease because procedures near this area risk affecting AV nodal conduction. It wouldn’t be in the left atrium, right ventricle, or interventricular septum.