Cardiology workup diagnosed pulmonary valve stenosis due to congenital bicuspid valvular anatomy.

Chen sign is described as the prominence of left basal pulmonary vasculature compared to the right base due to the asymmetric increase in pulmonary blood flow to the left lung. It is secondary to preferential blood flow into the left pulmonary artery after passing through the stenosed pulmonary valve during systole.

Enlargement of the left pulmonary artery is secondary to the same effect, causing post stenotic dilatation.