atrial septal defect
An atrial septal defect (ASD) is a congenital cardiac defect in which the wall (septum) between the upper chambers of the heart has a hole (defect) (atria). The heart begins as a single tube in early fetal development and later divides into four chambers. At any point during the process, abnormalities can occur, resulting in flaws in the muscle wall that typically separates the atria.
Although an ASD may not be discovered in childhood, if it is severe, it is usually noticeable by the age of 30. Small ASDs may not be found until later in life; nonetheless, they are frequently diagnosed due to cardiac enlargement and a distinctive heart sound (fixed split of the second heart sound). Children with symptomatic ASDs may become tired easily, breathe quickly with shortness of breath, and grow slowly.