When ONE error can cause Four Errors ! What is Monology of Tetralogy ?

The antero-cephalad deviation of the outlet septum, coupled with an anomalous relationship to the septoparietal trabeculations, results in a narrowing of the subpulmonary outflow tract. The obstructive muscular subpulmonary area thus created is a dynamic entity. The degree of stenosis created can be exacerbated by catecholamines, or a state of low intravascular volume, predisposing the patients to sudden and acute episodes of desaturation known as hypercyanotic spells .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 .

.