Pathological lesions causing pulmonary hypertension after closure of a ventricular septal defect.

A 15-year-old boy with a ventricular septal defect, pulmonary hypertension, Down's syndrome, and extremely thickened media (ETM) of the small pulmonary arteries died of heart failure and pulmonary hypertension 13 years after intracardiac repair. Microscopic examination of lung specimens collected prior to the intracardiac repair and at the time of autopsy revealed that the ETM had remained unchanged and that the arteries connected to the vessels with ETM had become severely thickened. The present case shows that even a small percentage of arteries with ETM can cause pulmonary hypertension, and illustrates one of the mechanisms of how pulmonary hypertension can fail to be resolved after intracardiac repair.