Tetralogy of Fallot Clinical Presentation

Updated: Sep 27, 2016
  • Author: Shabir Bhimji, MD, PhD; Chief Editor: Yasmine Subhi Ali, MD, FACC, FACP, MSCI  more...
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Presentation

History

The clinical features of tetralogy of Fallot (TOF) are directly related to the severity of the anatomic defects. 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.

Cyanosis generally progresses with age and outgrowth of pulmonary vasculature and demands surgical repair. The following factors can worsen cyanosis in infants with tetralogy of Fallot:

  • Acidosis
  • Stress
  • Infection
  • Posture
  • Exercise
  • Beta-adrenergic agonists
  • Dehydration
  • Closure of the ductus arteriosus

The predominant shunt is from right to left with flow across the VSD into the left ventricle (LV), which produces cyanosis and an elevated hematocrit value. When the pulmonary stenosis is mild, bidirectional shunting may occur. In some patients, the infundibular stenosis is minimal, and the predominant shunt is from left to right, producing what is called a pink tetralogy. Although such patients may not appear cyanotic, they often have oxygen desaturation in the systemic circulation.

Symptoms generally progress secondary to hypertrophy of the infundibular septum. Worsening of the RVOTO leads to RV hypertrophy, increased right-to-left shunting, and systemic hypoxemia.

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Physical Examination

Most infants with tetralogy of Fallot (TOF) are smaller than expected for age. Cyanosis of the lips and nail bed is usually pronounced at birth; after age 3-6 months, the fingers and toes show clubbing.

A systolic thrill is usually present anteriorly along the left sternal border. A harsh systolic ejection murmur (SEM) is heard over the pulmonic area and left sternal border. When the right ventricular (RV) outflow tract obstruction (RVOTO) (eg, from pulmonary atresia) is moderate, the murmur may be inaudible (more cyanotic patients have greater obstruction and a softer murmur). The S2 is usually single (the pulmonic valve closure is not heard). During cyanotic episodes, murmurs may disappear, which is suggestive of lessened RV outflow to the pulmonary arteries. In individuals with aortopulmonary collaterals, continuous murmurs may be auscultated. Thus, an acyanotic patient with tetralogy of Fallot (pink tet) has a long, loud, systolic murmur with a thrill along the RVOT

The following may also be noted:

  • RV predominance on palpation
  • May have a bulging left hemithorax
  • Aortic ejection click
  • Squatting position (compensatory mechanism)
  • Scoliosis (common)
  • Retinal engorgement
  • Hemoptysis
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