Case Reports: Echocardiographic diagnosis of atrioventricular septal defect without primum atrial septal defect: a relatively “common” congenital heart defect in Down’s syndrome

Atrioventricular septal defects (AVSD) are congenital heart defects characterized by a common atrioventricular (AV) junction guarded by an abnormal valve with variable presence of primum atrial septal defects (ASD) and inlet ventricular septal defects (VSD) (1). A less common form of AVSD occurs when the common leaflet is fused to either the atrial septum or to the crest of the ventricular septum, creating an AVSD with no interatrial or interventricular communications respectively. There have been case reports of AVSD with intact septa, where the diagnosis was made at necropsy (2). In 2005, we validated quantitative echocardiographic measurements that helped in diagnosing of AVSD with no primum ASD: the measurements of the left ventricle inlet to outlet distance ratio and the percentage of the left AV valve guarded by the mural leaflet (3). In this report we describe four more cases of AVSD without primum ASD diagnosed using the above echocardiographic measurements.