In 1888, Fallot described the anatomy as consisting of a subaortic ventricular septal defect, right ventricular infundibular stenosis, an aortic valve positioned to override the right ventricle, and right ventricular hypertrophy. Wide variation exists in the basic anatomic morphology, pathophysiology, clinical signs and symptoms, and surgical methods of therapy. Pathophysiology primarily is dependent upon severity of the right ventricular outflow tract obstruction. Incidence is slightly higher in males than females. Cyanosis develops within the first few years of life.
Symptoms generally progress secondary to hypertrophy of the infundibular septum.
Cyanosis occurs and demands surgical repair. Dyspnea on exertion is common. These spells can be aborted with relatively simple procedures. The rare patient with TOF may remain marginally and imperceptibly cyanotic or acyanotic and asymptomatic into adult life. Severe cyanosis may present at birth in a patient with TOF and associated pulmonary atresia.