Atypical common arterial trunk with neonatal cyanosis caused by truncal valve-related obstruction of a sinus-origin pulmonary trunk.

A neonate with common arterial trunk presented with severe cyanosis rather than pulmonary overcirculation. Echocardiography, cardiac CT, catheterisation, and surgery showed a pulmonary trunk arising from a truncal valvar sinus, with systolic obstruction by a dysplastic truncal cusp. Staged palliation restored antegrade pulmonary flow, allowed pulmonary arterial growth, and enabled successful complete repair.