From the Guidelines
The Bundle of His is displaced posteriorly in relation to the posterior leaflet of the mitral valve in a transitional atrioventricular (AV) canal. This anatomical relationship is crucial in understanding the potential risks associated with surgical procedures involving the mitral valve, particularly those addressing the posterior leaflet, as damage to the Bundle of His could result in heart block 1. The Bundle of His emerges from the AV node, which is positioned posterior and inferior to the coronary sinus, and travels through the central fibrous body before dividing into the left and right bundle branches. Key points to consider in this context include:
- The abnormal activation sequence of the ventricles due to the posterior displacement of the Bundle of His and the left bundle branch 1
- The presence of a common AV annulus, guarded by five leaflets, in an AVSD (AV canal or endocardial cushion defect) 1
- The potential for surgical procedures to damage the Bundle of His, resulting in conduction disturbances, particularly in patients with Down syndrome who may present with unoperated complete AVSD and Eisenmenger syndrome 1 Understanding this anatomical relationship is essential for cardiac surgeons performing mitral valve repairs or replacements to minimize the risk of iatrogenic conduction abnormalities.
From the Research
Location of the Bundle of His
The location of the Bundle of His in relation to the posterior leaflet of the mitral valve in a transitional atrioventricular (AV) canal is not directly described in the provided studies. However, some information can be inferred from the studies:
- The Bundle of His is located near the tricuspid septal leaflet (TSL) and the mitral valve leaflet (MVL) 2.
- In patients with prosthetic cardiac valves, the His bundle can be localized using anatomical landmarks such as the aortic valve replacement (AVR) or tricuspid valve (TV) ring 3.
- In a patient with an atrioventricular canal defect, the His bundle was localized using 3-dimensional mapping and was found to be in a posterior-inferior position 4.
- The attachment of the posterior mitral valve leaflet is a band-like structure positioned between the left ventricular muscle and the left atrium, and is connected to the membranous septum and the left and right fibrous trigone 5.
Relation to the Posterior Leaflet of the Mitral Valve
Some key points related to the posterior leaflet of the mitral valve are:
- The posterior leaflet of the mitral valve is attached to a band-like structure, which is part of the greater structural system connected to the membranous septum and the left and right fibrous trigone 5.
- The Bundle of His is located near the mitral valve leaflet (MVL), but the exact relation to the posterior leaflet is not specified 2.
- The location of the His bundle in relation to the posterior leaflet of the mitral valve may vary depending on the individual anatomy and the presence of any cardiac defects or prosthetic valves 3, 4.