Tetralogy of Fallot is a congenital heart defect that consists of four specific heart abnormalities. These include a ventricular septal defect (a hole between the heart's lower chambers), pulmonary stenosis (narrowing of the outflow tract from the heart), right ventricular hypertrophy (thickening of the heart muscle), and an overriding aorta (where the aorta is positioned directly over the ventricular septal defect). This condition affects blood flow and can lead to reduced oxygen levels in the blood, causing cyanosis, or a bluish tint to the skin. Treatment typically involves surgery to correct the defects, allowing for improved heart function and quality of life for those affected.