Triangle of atrioventricular node

The triangle of atrioventricular node (Triangle of Koch) is an anatomical region within the right atrium of the heart that serves as a critical landmark for electrophysiologists due to its relationship with the atrioventricular (AV) node. Its boundaries are defined by three structures: the tendon of Todaro (a fibrous structure extending from the Eustachian valve to the central fibrous body), the orifice of the coronary sinus, and the septal leaflet of the tricuspid valve. The apex of the triangle is located near the central fibrous body, while the base is at the level of the coronary sinus ostium.

The compact AV node is situated at the apex of the triangle of Koch, making this region essential for procedures such as catheter ablation of AV nodal reentrant tachycardia (AVNRT).The triangle also contains the AV nodal artery and is closely related to the membranous septum and the His bundle.