patients to sudden and acute episodes of desaturation
known as hypercyanotic spells [9,10].
The obstruction to flow into the lungs often extends
beyond the subpulmonary outflow tract itself. The pulmonary
valve may be hypoplastic, with abnormally functioning
leaflets, often having a bifoliate configuration.
Not infrequently, the pulmonary trunk, and the right and
left pulmonary arteries, are diminutive, exhibiting additional
focal areas of narrowing [11].