Neonates with congenital cardiac defects with increased pulmonary blood flow.

Generally, cardiac lesions with increased pulmonary blood flow demonstrate cardiomegaly, increased pulmonary vascular markings, and pulmonary congestion on the chest x-ray. These findings occur as a result of the following: (1) A left-to-right shunt or mixing lesion in which excess volume of blood flow causes dilation of cardiac chambers, resulting in the appearance of cardiomegaly, and in which increased pulmonary artery blood flow causes increased pulmonary vascular markings; (2) Obstruction of blood flow that produces pulmonary venous hypertension and resultant pulmonary edema.