Which clinical history findings are characteristic of tetralogy of Fallot (TOF) in infants?

Updated: Nov 13, 2018
  • Author: Shabir Bhimji, MD, PhD; Chief Editor: Yasmine S Ali, MD, FACC, FACP, MSCI  more...
  • Print

The clinical presentation of infants with tetralogy of Fallot (TOF) is included for comparison to that of adults.

Presentation of pediatric patients with tetralogy of Fallot

Most infants with tetralogy of Fallot have difficulty with feeding, and failure to thrive (FTT) is commonly observed. Infants with pulmonary atresia may become profoundly cyanotic as the ductus arteriosus closes unless bronchopulmonary collaterals are present. Occasionally, some children have just enough pulmonary blood flow and do not appear cyanotic; these individuals remain asymptomatic, until they outgrow their pulmonary blood supply.

At birth, some infants with tetralogy of Fallot do not show signs of cyanosis, but they may later develop episodes of bluish pale skin during crying or feeding (ie, "Tet" spells). Hypoxic tet spells are potentially lethal, unpredictable episodes that occur even in noncyanotic patients with tetralogy of Fallot. The mechanism is thought to include spasm of the infundibular septum, which acutely worsens the right ventricular (RV) outflow tract obstruction (RVOTO). These spells can be aborted with relatively simple procedures.

A characteristic fashion in which older children with tetralogy of Fallot increase pulmonary blood flow is to squat. Squatting is a compensatory mechanism, of diagnostic significance, and highly typical of infants with tetralogy of Fallot. Squatting increases peripheral vascular resistance (PVR) and thus decreases the magnitude of the right-to-left shunt across the ventricular septal defect (VSD). Exertional dyspnea usually worsens with age. Occasionally, hemoptysis due to rupture of the bronchial collaterals may result in the older child.

The rare patient may remain marginally and imperceptibly cyanotic, or acyanotic and asymptomatic, into adult life.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!