European Journal of Cardio-Thoracic Surgery, Vol 3, 283-287, Copyright © 1989 by European Association for Cardio-thoracic Surgery
The conduction bundle at the atrioventricular junction. An anatomical study
H Kurosawa and AE Becker
Department of Pathology, University of Amsterdam, Academic Medical Center, The Netherlands.
The variability in the topographical anatomy of the conduction bundle at
the site of the atrioventricular junction has been studied in four normal
human hearts. The junctional area has been removed en bloc and serially
sectioned. The conduction bundle and adjacent structures such as the
posterior limb of the trabecula septomarginalis and the membranous septum
have been reconstructed based on calculations from the histological
sections. The study reveals marked variability particularly in the extent
of the posterior limb of the trabecula septomarginalis. In one instance,
the muscle was almost totally absent so that the branching bundle was
located in a midline position and subendocardial both to the right and the
left ventricular septal surface. In two hearts, the posterior limb of the
trabecula septomarginalis had ramified so that only a small segment of the
conduction bundle was covered by muscle. In the remaining case, a well-
developed posterior limb of the trabecula septomarginalis completely
covered the conduction axis thus accounting for the left-sided position of
the bundle. The variability encountered may render the conduction bundle
vulnerable to the tensile strain of the tricuspid valve apparatus,
enhancing the natural process of wear and tear which may lead to disruption
of conduction fibres and heart block, particularly in the elderly. Since
the detailed topographical anatomy of the conduction bundle in the
atrioventricular junctional area appears to be highly variable from one
individual to another, meticulous inspection is mandatory once the area is
manipulated at surgery.
