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 abnormally between the left and right ventricles, which can lead to increased blood flow to the lungs and potential heart complications. Symptoms of a VSD can vary based on the size of the defect. Small VSDs may cause no noticeable symptoms, while larger defects can lead to heart failure, difficulty breathing, and poor growth in infants. Treatment options include monitoring, medication, or surgical repair, depending on the severity of the condition.