Congenital heart disease and congenital heart defects are categorized into two groups, acyanotic heart defects and cyanotic heart defects. Both defects prevent the heart from correctly pumping blood. In an acyanotic heart defect, the blood flows from the left side to the right side of the heart because of a structural defect. However, the level of oxygen in the blood is not affected. A cyanotic heart defect causes low levels of oxygen in the blood which can result in a blue tint to the patient’s skin.