❤️ Atrial Septal Defect (ASD) 🔹 Definition An Atrial Septal Defect (ASD) is a congenital heart defect in which there is an abnormal opening in the interatrial septum, the wall separating the right and left atria of the heart. This defect allows oxygen-rich blood from the left atrium to flow into the right atrium, resulting in a left-to-right shunt. This causes increased blood flow to the lungs, volume overload in