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Published on: May 21, 2017
The atrioventricular conduction axis and the aortic root-Inferences for transcatheter replacement of the aortic valve
Yolanda Macías1, Justin T Tretter2, Damián Sánchez-Quintana3
1Department of Medical and Surgical Therapeutics, Faculty of Veterinary, University of Extremadura, Cáceres, Spain.
Insights
Conduction problems after transcatheter aortic valve replacement can be reduced by understanding the relationship between the conduction axis and the aortic root. This study clarifies the anatomy near the right coronary leaflet hinge.
Area of Science:
- Cardiac Anatomy
- Electrophysiology
- Cardiovascular Surgery
Background:
- Conduction abnormalities are a known complication following transcatheter aortic valve replacement (TAVR).
- Understanding the precise anatomical relationship between the cardiac conduction system and the aortic root is crucial for mitigating these risks.
Purpose of the Study:
- To investigate the spatial relationship of the atrioventricular conduction axis to the aortic root structures.
- To identify anatomical landmarks that may predict or explain conduction issues post-TAVR.
Main Methods:
- Histological analysis of serial sections from human hearts.
- Examination of sections perpendicular to the triangle of Koch base and the aortic root.
- Definition and assessment of the infero-septal recess and its relationship to the conduction axis.
Main Results:
- The atrioventricular conduction axis typically penetrates the rightward wall of the infero-septal recess, branching before entering the subaortic outflow tract.
- The left bundle branch is usually located close to the hinge of the right coronary leaflet (average 3.3 mm).
- Anatomical variations, particularly the presence or absence of the infero-septal recess, significantly alter the conduction axis proximity to aortic valve structures.
Conclusions:
- The study redefines aspects of the right fibrous trigone and central fibrous body based on anatomical findings.
- Proximity of the conduction axis to the right coronary leaflet hinge is a key anatomical feature.
- Knowledge of infero-septal recess depth and ventricular septal angulation may aid in preventing conduction problems during TAVR.
Abstract:
Conduction problems still occur following transcatheter aortic valvar replacement. With this in mind, we have assessed the relationship of the conduction axis to the aortic root. We used serial histological sections, made perpendicular to the base of the triangle of Koch in nine hearts, and perpendicular to the aortic root in 11 hearts. We first defined the extent of the fibrous tissues forming the boundaries of an infero-septal recess of the subaortic outflow tract, found in all datasets but one. When the recess was present, the axis penetrated through its rightward wall, giving rise to the left bundle branch prior to entering the outflow tract. The axis itself was usually on the crest of the ventricular septum, but could be deviated leftward or rightward. Its proximity to the virtual basal plane reflected the angulation of the muscular septum. On average, the superior edge of the left bundle was within 3.3 mm of the hinge of the right coronary leaflet, with a range from 0.4 to 10.2 mm. The arrangement was markedly different in the case lacking an infero-septal recess. Our findings necessitated a redefinition of the right fibrous trigone and the central fibrous body. The atrioventricular conduction axis, having entered the aortic root, is usually closest at the hinge of the right coronary leaflet. Knowledge of the depth of the infero-septal recess, and the angulation of the muscular ventricular septal, may help to avoid conduction problems following transcatheter implantation of the aortic valve.
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