Tetralogy of Fallot is a rare condition caused by a combination of four heart defects that are present at birth (congenital). The four abnormalities that make up the tetralogy of Fallot include pulmonary valve stenosis, ventricular septal defect, overring aorta, and right ventricular hypertrophy.
These defects cause oxygen-poor blood to flow out of the heart and to the rest of the body. Infants and children with tetralogy of Fallot usually have blue-tinged skin because their blood doesn’t carry enough oxygen. Tetralogy of Fallot is often diagnosed during infancy or soon after. However, tetralogy of Fallot might not be detected until later in some adults, depending on the severity of the defects and symptoms.
Symptoms include a bluish coloration of the skin, shortness of breath and rapid breathing, loss of consciousness, clubbing of fingers and toes, poor weight gain, tiring easily during exercise, irritability, prolonged crying, and a heart murmur.
Tetralogy of Fallot, Mayo Clinic (Mar. 9, 2018), https://www.mayoclinic.org/diseases-conditions/tetralogy-of-fallot/symptoms-causes/syc-20353477