Name a non-cardiac condition that may lead to secondary pulmonary hypertension in children.

Chronic lung disease or sickle cell disease is indeed a non-cardiac condition that can lead to secondary pulmonary hypertension in children. Chronic lung disease directly affects lung function and oxygenation, which can increase pressure in the pulmonary vasculature over time. Conditions such as bronchopulmonary dysplasia or other forms of chronic respiratory impairment can lead to prolonged hypoxia, vasoconstriction, and thus pulmonary hypertension.

Sickle cell disease contributes to this condition through sickling of red blood cells that can cause vaso-occlusive crises, leading to ischemia and damage in the lungs. This results in an inflammatory response and ultimately an increase in pulmonary pressure. Both of these conditions illustrate how factors outside of the heart can have a significant impact on the pulmonary circulation and lead to secondary pulmonary hypertension.