Fallot's tetralogy. X-ray of the chest of an infant with Fallot's tetralogy and rickets. Fallot's tetralogy is a congenital heart defect that results in insufficient oxygen in the blood (cyanosis), which can cause the baby to turn blue. It is caused by 4 malformations of the heart. There is a hole between the 2 bottom chambers (ventricles) of the heart, a narrowing of the valve leading to the pulmonary arteries, a thickening of the right ventricle and blood can enter the aorta from both ventricles, not only the left. Treatment is with a series of operations. Rickets, soft bones due to a lack of vitamin D, has lead to a misshapen chest. It is treated with vitamin D supplements.