Koch's triangle

Koch's triangle is an anatomical area located in the superficial paraseptal endocardium of the right atrium, which its angles are coronary sinus orifice, tendon of Todaro and atrioventricular node. Also the elements anatomically near to it, are the insertion of the tricuspid valve, membranous septum, and the Eustachian ridge. This triangle ends at the site of the coronary sinus orifice inferiorly and, continuous with the sub-Eustachian pouch. The tendon of Todaro forms the hypotenuse of the triangle and the base is formed by the CSO and the vestibule of the right atrium. Variations in the size of Koch's triangle are common among people with different age and gender.