The obstruction to right ventricular outflow creates a right-to-left shunt that leads to cyanosis.

There is no evidence that early tapping of cerebrospinal fluid by lumbar puncture or ventricular tap reduces the risk of shunt dependence, disability, multiple disability or death.

Mechanism is a blood shunt from left to right lead to desynchrony of the ventricular repolarization, also with the right ventricular hypertrophy.