Tetralogy of Fallot (TOF) is a congenital defect caused due to the improper development of the right side of the heart. It is a complex of four different cardiac defects, that include ventricular septal defect, narrowing of the pulmonic outflow tract (right ventricular infundibular stenosis), right ventricular hypertrophy, and aortic valve positioned to override the right ventricle. The overall effect of these defects is that the blood flow to the lungs in restricted, leading to low levels of oxygen (hypoxia) in the blood. Cyanosis follows, and the baby develops a bluish tint in the skin, fingers, and lips.
TOF is the most common of all cyanotic congenital heart defects, and can be seen in one out of every 1000 babies with congenital heart disease. TOF can be clearly diagnosed using ECG, chest X-ray, echocardiogram, and cardiac catheterization. Immediate treatment to manage hypoxia in infants involves administration of beta blockers like propanolol, or morphine and phenylephrine. However, corrective surgery is required early in life to conclusively treat the disease. Surgery includes widening of the narrowed pulmonary valve, and closure of the ventricular septal defect.