label: Atrioventricular Septal Defect
label_lc: atrioventricular septal defect
description: A congenital heart malformation characterized by abnormalities in the anatomic structures that relate to the endocardial cushions. These abnormalities can include defects in the lower part of the atrial septum and the ventricular septum and lack of separation of the mitral and tricuspid valves.