A ventricular septal defect (VSD) is a congenital heart condition characterized by a hole in the wall (septum) that separates the heart's two lower chambers, known as the ventricles. This defect allows blood to flow from the left ventricle to the right ventricle, which can lead to increased blood flow to the lungs and potential heart complications. VSDs can vary in size and may cause symptoms such as shortness of breath, fatigue, or poor growth in infants. Treatment options depend on the size of the defect and the severity of symptoms, ranging from monitoring to surgical repair.