Congenital alveolar capillary dysplasia with misalignment of pulmonary veins associated with hypoplastic left heart syndrome.

Three full-term infants died in the first month of life with hypoplastic left heart syndrome (HLH) and persistent pulmonary hypertension (PPH). At postmortem examination, they were found to have alveolar capillary dysplasia with misalignment of pulmonary veins (ACD with MPV). The association of HLH syndrome, and ACD with MPV with intestinal malrotation and/or obstruction, is unique. Decreased blood flow in the ascending aorta in fetuses with left outflow tract obstruction might cause vasoconstriction of pulmonary arterioles to maintain cerebral perfusion. Vasoconstriction early during embryogenesis might lead to decreased growth and development of alveolar capillaries and pulmonary veins. This results in pulmonary hypertension, and the arterial blood is forced to bypass the deficient capillary bed and can drain only via the anomalous bronchial veins.