Atrial development is a complex process in embryogenesis where the heart’s upper chambers, the atria, form and differentiate. This process involves the creation of the atrial septum, which divides the atria into the right and left chambers, ensuring proper blood flow and separation of oxygenated and deoxygenated blood. Congenital defects in atrial development can lead to atrial septal defects (ASDs), where the septum does not form correctly, resulting in an abnormal opening between the atria.