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, ชักนำให้เกิดโรค the