The particular anatomy of atrioventricular septal defect with a common valvar orifice in patients with Down syndrome: an echocardiographic study.

OBJECTIVES

Atrioventricular septal defect with a common valvar orifice is associated with Down syndrome in almost half of cases. Clinical studies have shown that associated tetralogy of Fallot is more frequent in Down patients. The aim of this study was to compare the anatomy of the ventricles and of the ventricular component of the atrioventricular septal defect, looking for an outlet septum malalignment like in tetralogy of Fallot, in patients with and without Down syndrome.

METHODS

We reviewed retrospectively the echocardiographic examinations of all consecutive patients hospitalized with atrioventricular septal defect with a common orifice between 01/01/2016 and 01/09/2023. Anatomic and functional characteristics were compared between Down and non-Down patients.

RESULTS

A total of 310 patients were included (Down syndrome 210, 67.7 %). Outlet extension of the ventricular component of the defect with outlet septum anterior malalignment was found in 90.6 % of Down vs 12.8 % of non-Down patients (p < 0.001). Hypoplasia and apical filling of the right ventricle were more frequent in Down patients (p < 0.001). Associated tetralogy of Fallot was found in 16 Down vs 1 non-Down patients (p = 0.04). Atrioventricular septal malalignment was observed only in Down patients.

CONCLUSION

Outlet extension of the ventricular component of the defect is the rule in atrioventricular septal defect with a common orifice in Down patients, which could influence surgical repair. Hypoplastic right ventricle occurs only in Down patients. The presence of these characteristics in a fetus with atrioventricular septal defect with a common orifice should raise awareness of the high risk of associated Down syndrome.