Structural cardiac malformations present at birth, which include atrial or ventricular septal defects, tetralogy of Fallot, transposition of the great arteries, and valvular abnormalities. Clinical presentations vary but often include cyanosis, arrhythmia, and heart failure. While the diagnosis may be apparent at birth or during early childhood, it may also be asymptomatic and undetected until the adult years, as is often the case with atrial septal defects and bicuspid aortic valves.