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. Birth weight is low.
Growth is retarded.
More cyanotic patients have greater obstruction and a softer murmur. Ablation of cells of the neural crest has been shown to reproduce conotruncal malformations. These abnormalities are associated with the DiGeorge syndrome and branchial arch abnormalities. Oximetry is particularly useful in the dark-skinned patient or the anemic patient whose level of cyanosis is not apparent. Hematology Prolonged cyanosis causes reactive polycythemia that increases the oxygen-carrying capacity.