From the Guidelines
The Bundle of His in a transitional atrioventricular (AV) canal is located anteriorly and inferiorly to the aortic valve, with its course being closely related to the non-coronary cusp of the aortic valve, as described in the context of cardiac conduction and AV canal defects 1. This anatomical relationship is crucial for understanding the potential risks of conduction disturbances during cardiac procedures involving the aortic valve, such as transcatheter aortic valve replacement (TAVR) or aortic valve surgeries. The Bundle of His emerges from the AV node in the right atrium, penetrates through the central fibrous body, and then courses along the lower border of the membranous septum before dividing into the left and right bundle branches. Key points to consider include:
- The proximity of the Bundle of His to the aortic valve explains the risk of conduction disturbances during certain cardiac procedures 1.
- The Bundle of His contains specialized cardiac conduction tissue that transmits electrical impulses from the AV node to the ventricles, coordinating proper contraction of the heart chambers.
- Understanding this anatomical relationship is essential for cardiac surgeons and interventional cardiologists to avoid iatrogenic heart block during procedures involving the aortic valve or AV canal defect repairs.
- Patients with specific forms of CHD, such as AVSD, may be more susceptible to surgical or catheter-induced AV block and may require periodic assessment of AV conduction 1.
- The most recent guidelines emphasize the importance of considering the anatomical relationship between the Bundle of His and the aortic valve in the management of patients with bradycardia and cardiac conduction delay 1.
From the Research
Location of the Bundle of His
- The Bundle of His is located near the membranous septum, between the noncoronary cusp and right coronary cusp of the aortic valve 2.
- The superior border of the membranous portion of the interventricular septum (MPIS) is in close relationship with the aortic valve, and its upper part is usually in direct continuity with the attachments of both right and posterior aortic cusps 3.
- The distance between the MPIS superior border and the attachment of the right aortic cusp is not greater than 5.89 mm, and the distance between the superior border of the MPIS and the attachment of the posterior aortic cusp is not greater than 5.63 mm 3.
- The lower limit of the membranous septum is considered an anatomic landmark for the emergence of the Bundle of His into the left ventricle 4.
Relationship with the Aortic Valve
- The Bundle of His is located just below the aortic valve in proximity to the membranous septum 2.
- The aortic valve is closely related to the membranous portion of the interventricular septum, with the superior border of the MPIS being in direct continuity with the attachments of the aortic cusps 3.
- The presence of calcium in the device landing zone, which includes the area near the aortic valve, is associated with an increased risk of conduction abnormalities after transcatheter aortic valve replacement (TAVR) 4.