From the Guidelines
The aortic valve is anatomically located near the bundle of His, while the mitral valve is close to the atrioventricular node, indicating a specific relationship between the aortic valve and the AV node. The aortic valve sits at the junction between the left ventricle and the ascending aorta, and is anterior and superior to the AV node, with the membranous interventricular septum positioned between them 1. This proximity is clinically significant because pathological processes affecting the aortic valve, such as infective endocarditis or aortic valve surgery, can potentially damage the AV conduction system, leading to heart blocks.
Key Anatomical Relations
- The AV node is located in the floor of the right atrium, within the interatrial septum, specifically in an area called the triangle of Koch.
- The aortic valve is positioned anterior and superior to the AV node, with the membranous interventricular septum between them.
- The bundle of His is near the aortic valve, which is relevant for conduction abnormalities during aortic valve surgery 1.
Clinical Implications
- Aortic valve replacement surgery requires careful management to avoid damaging the AV node and the bundle of His, which could result in conduction abnormalities requiring permanent pacemaker implantation.
- The need for pacemaker placement is frequent after aortic valve replacement, and patients with new atrioventricular block that does not resolve should undergo pacemaker implantation before discharge for persistent symptomatic or hemodynamically significant bradycardia 1.
From the Research
Anatomical Relations of the Aortic Valve to the Atrioventricular (AV) Node
The aortic valve is a complex structure with leaflets suspended within the functional aortic annulus (FAA) 2. However, the provided studies do not directly describe the anatomical relations of the aortic valve to the atrioventricular (AV) node.
Relations of the AV Node to Surrounding Structures
- The AV node artery originated from the right coronary artery in 73% of examined cases, and from the left coronary artery in 27% of cases 3.
- 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 3.
- The lower pole of the AV node was located vertically above the tricuspid septal leaflet (TSL) in 100% of cases, and at the level of the muscular interventricular septum in 65% of cases 4.
- The upper pole of the compact AV node was located at the level of the mitral valve leaflet (MVL) in 50% of cases 4.
- The penetrating bundle of His was seen at the level of the TSL, while the branching bundle of His was situated 1.9±1.5 mm inferior to the TSL 4.
Clinical Implications
- Understanding the topography of the AV conduction system in relation to the tricuspid and mitral valves can help reduce complications such as cardiac conduction disorders during heart valve surgeries and radiofrequency catheter ablations 4.
- A rectangular area (2.5 mm × 12 mm) in the Koch's triangle was devoid of AV nodal tissue and could be labeled as a safe area with no risk of conduction defects during valve surgeries 4.