From the Guidelines
The AV node in a transitional atrioventricular (AV) canal is positioned posterior and inferior to the coronary sinus, which is adjacent to the posterior leaflet of the mitral valve. This anatomical relationship is crucial in understanding the potential risks and challenges associated with surgical repair of AV canal defects. According to the ESC guidelines for the management of grown-up congenital heart disease 1, the AV node is located posterior and inferior to the coronary sinus, which is consistent with its position in relation to the posterior leaflet of the mitral valve.
Key points to consider in this context include:
- The AV node's position makes it vulnerable to injury during surgical repair of AV canal defects
- In transitional AV canal defects, the AV node may be displaced more posteriorly and inferiorly compared to its normal position, increasing surgical risk
- The node's proximity to the posterior leaflet of the mitral valve means that careful attention must be paid during mitral valve repair or replacement procedures to avoid damage to the conduction system
- Understanding this relationship is essential for cardiac surgeons to prevent iatrogenic heart block, which would necessitate permanent pacemaker implantation, as noted in the guidelines 1.
The embryological development of the AV canal explains this anatomical arrangement, as the AV node develops in close association with the endocardial cushions that form the AV valves. This knowledge is critical in minimizing the risk of complications during surgical procedures involving the AV canal and mitral valve, and is supported by the guidelines 1.
From the Research
Location of the Atrioventricular (AV) Node
- The location of the atrioventricular (AV) node in relation to the posterior leaflet of the mitral valve is not directly described in the provided studies.
- However, study 2 describes the topography of the AV conduction system in relation to the tricuspid and mitral valves, and found that the upper pole of the compact AV node was located at the level of the mitral valve leaflet (MVL) in 50% of cases.
- Study 3 describes the topographical relationship of the AV node artery and mitral valve annulus fibrosus, and found that the left AV node artery was closely related to the mitral valve attachment, especially at the area of the left proximal part of the posterior leaflet.
- Studies 4, 5, and 6 do not provide direct information on the location of the AV node in relation to the posterior leaflet of the mitral valve.
Relation to the Posterior Leaflet of the Mitral Valve
- The provided studies do not specifically describe the location of the AV node in a transitional atrioventricular (AV) canal in relation to the posterior leaflet of the mitral valve.
- However, study 3 suggests that the AV node artery is closely related to the mitral valve attachment, which may imply a close relationship between the AV node and the posterior leaflet of the mitral valve 3.
- Further studies would be needed to determine the exact location of the AV node in relation to the posterior leaflet of the mitral valve in a transitional AV canal.