The<unk>  is a defect in the<unk>  septum at the level of the tricuspid and mitral valves. This is sometimes known as an endocardial cushion defect because it often involves the endocardial cushion, which is the portion of the heart where the<unk>  septum meets the ventricular septum and the mitral valve meets the tricuspid valve. Endocardial cushion defects are associated with abnormalities of the atrioventricular valves (the mitral valve and the tricuspid valve). These include the cleft mitral valve, and the single atrioventricular valve (a single large, deformed valve that flows into both the right ventricle and the left ventricle). Endocardial cushion defects are the most common congenital heart defect that is associated with Down syndrome.
Ostium primum atrial septal defect
Double aortic arch
Double inlet left ventricle
Interrupted aortic arch
Sinus venosus atrial septal defect
Tricuspid atresia
Double outlet right ventricle
Atrioventricular septal defect