Tetralogy of Fallot is a complex birth defect that involves four heart defects. (1) A ventricle septal defect, which is a hole between the hearts two lower chambers, which allows oxygen-rich and poor blood to mix. (2) Pulmonary Stenosis, meaning that the valve that carries blood from the heart to the lungs is narrower than normal, making it difficult for blood to pass. (3) Right ventricular hypertrophy, meaning the walls of the right lower chamber are thicker than normal. (4) Overriding aorta, which is a defect in the main artery that carries blood to the body. This condition occurs in about 5 out of every 10,000 newborns, and occurs equally in males and females. The causes are unknown, but risk factors during pregnancy are believed to include: diabetes, poor nutrition, and measles. If you have tetralogy of fallot, not enough blood is able to reach the lungs to get oxygen, so the body receives oxygen-poor blood instead of oxygen-rich blood like it needs. Without enough oxygen in the blood the skin will develop a blue tint. Other symptoms include: difficulty breathing, tiredness, unresponsiveness, and fainting. Treatment for this condition usually requires open-heart surgery.