This anatomical study details the abnormal location and extensions of the AV node and bundle in tricuspid atresia, providing important anatomical landmarks for surgical intervention.
Anatomical variants may guide AV node protection in tricuspid atresia surgery; leaves open validation in larger cohorts or imaging.
The atrioventricular conduction tissues in 14 hearts with absence of the right atrioventricular connection ('tricuspid atresia') were studied by serial sectioning. In all cases, the atrioventricular node lay in the floor of the right atrium, posterior to the tendon of Todaro, but in all but one case it extended anteriorly either medial or lateral to the insertion of the tendon in a way not seen in the normal heart. The common bundle frequently arose from the anterior or lateral extensions of the node and, after penetration of the central fibrous body, came to lie on the right wall of the main ventricular chamber at the point of junction with the septum separating this chamber from the outlet chamber. In all but 3 cases, branching of the bundle occurred posterior to the outlet foramen. The distribution of the left bundle characteristically favoured the posterior part of the main chamber and the right bundle passed inferior to the outlet foramen to ramify in the trabecular zone of the outlet chamber.
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Dickinson et al. (1979) studied this question.