GOOD PEDIATRIC CARDIOLOGIST IN YELAHANKA ASD, or atrial septal defect, is a type of congenital heart disease characterized by an abnormal hole in the wall separating the two upper chambers of the heart, the left and right atria. This defect allows oxygenated blood from the left atrium to leak into the right atrium, which can cause the right side of the heart and lungs to work harder over time, potentially leading to complications like pulmonary hypertension, heart rhythm abnormalities, or heart failure if left untreated. While many small ASDs close on their own, larger or persistent ones may require monitoring or intervention such as catheter-based closure or surgery.