Which statement about the AV node location is true?

Which statement about the AV node location is true?

• A. It is located at the apex of the triangle of Koch
• B. It is located at the fossa ovalis
• C. It is located in the left atrial appendage
• D. It lies at the posterior interatrial septum near the pulmonary veins

Answer: (A)

The key point is where the AV node sits in the right atrium, specifically within Koch’s triangle. This triangle is formed by the tricuspid annulus anteriorly, the tendon of Todaro superiorly, and the coronary sinus ostium posteriorly. The AV node lies in the inferior part of this triangle, at its apex, near the interatrial septum and adjacent to the membranous portion of the septum from which the His bundle emerges. This location explains why manipulation in this area carries risk to AV conduction during procedures. The other structures mentioned are not the AV nodal site: the fossa ovalis is just a septal landmark in the interatrial septum and not where the AV node resides; the left atrial appendage is a left atrial structure with no nodal tissue there; and the posterior interatrial septum near the pulmonary veins is more related to left atrial conduction and atrial arrhythmia triggers, not the AV node location.

The key point is where the AV node sits in the right atrium, specifically within Koch’s triangle. This triangle is formed by the tricuspid annulus anteriorly, the tendon of Todaro superiorly, and the coronary sinus ostium posteriorly. The AV node lies in the inferior part of this triangle, at its apex, near the interatrial septum and adjacent to the membranous portion of the septum from which the His bundle emerges. This location explains why manipulation in this area carries risk to AV conduction during procedures.

The other structures mentioned are not the AV nodal site: the fossa ovalis is just a septal landmark in the interatrial septum and not where the AV node resides; the left atrial appendage is a left atrial structure with no nodal tissue there; and the posterior interatrial septum near the pulmonary veins is more related to left atrial conduction and atrial arrhythmia triggers, not the AV node location.