Cross sectional echocardiographic assessment of the extent of the atrial septum relative to the atrioventricular junction in atrioventricular septal defect

Objective-To study patients with atrioventricular septal defect to determin e the pathognomonic morphological features of the lesion and the relation b etween the septal structures and the atrioventricular junction. Setting-Tertiary level paediatric cardiology centre. Methods-Cross sectional echocardiograms from 60 patients were reviewed usin g qualitative and quantitative analysis. The unifying feature was the prese nce of a common atrioventricular junction. The overall dimensions of the se ptal defect were determined and related to the plane of the common junction ; the extent of both the atrial and the ventricular septal components was t hen measured according to the site of closure of the bridging leaflets. Results-In 48 cases, the common junction was guarded by a common valvar ori fice, but in 12 cases there were separate right and left valvar orifices. I rrespective of the valvar morphology, no significant difference was found b etween the groups in terms of the dimensions of the atrial and ventricular septal components. In all patients, the hole permitting shunting at atrial level extended below the plane of the atrioventricular junction, with a var iable position of the leading edge of the atrial septum itself. Conclusions-The atrioventricular junction is a common structure irrespectiv e of valvar morphology. In spite of the presence of unequivocal shunting at atrial level, the atrial septum is usually a well formed structure, even e xtending in some below the level of the common atrioventricular junction.