Fallot's tetralogy Fal·lot's tetralogy (fā-lōz')
n.
A congenital malformation of the heart characterized by a defect in the ventricular septum, misplacement of the origin of the aorta, narrowing of the pulmonary artery, and enlargement of the right ventricle. Also called Fallot's tetrad, tetralogy of Fallot.