TETRALOGY of FALLOT:

1. RV outflow obstruction (pulmonary stenosis - subvalvular, valvular, supravalvular)

2. VSD

3. overriding of the VSD by the aorta

4. RV hypertrophy

CLINICAL FEATURES:

1. cyanosis - in spite of: cyanosis may be absent in the newborn, or in patients with mild right ventricular outflow obstruction ("acyanotic tetralogy of Fallot")

2. the subvalvular component of the RV outflow obstruction is dynamic (may increase under adrenergic stimulation) - sudden cyanosis, often after feeding or a crying attack, sometimes with unconsious and apnoea ("Fallot's spells")

3. in older children cyanosis becomes apparent, with stunting of growth, digital clubbing and polycythemia (relief by squatting after exertion)

4. loud ejection systolic murmur in the pulmonary area

5. polycythemia in some patients

6. ECG - right ventricular hypertrophy

7. CXR - abnormal small pulmonary artery, "boot-shaped" heart