Endocardial Cushion Defects (ECDs), also known as atrioventricular septal defects (AVSDs), are congenital heart abnormalities that affect the structure of the heart's valves and septum. These defects occur when the endocardial cushions, which help form the walls between the heart chambers, do not fully develop. ECDs are characterized by a range of symptoms including heart murmurs, poor growth, and difficulty breathing. These defects can be classified as partial or complete, depending on the extent of the malformation. Synonyms for Endocardial Cushion Defects include atrioventricular septal defects, ECDs, AVSDs, and septal abnormalities. Early diagnosis and prompt medical intervention are crucial in managing ECDs and improving overall heart health.