See Picture 1 for a schematic illustration of these abnormalities. Wide variation exists in the basic anatomic morphology, pathophysiology, clinical signs and symptoms, and surgical methods of therapy. Natural history is determined mainly by the degree of RVOT 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 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.