Diffuse pulmonary microvascular arteriovenous communication developed in an 8-year-old girl with a patent ductus venosus. Tc-99m macroaggregated albumin (MAA) pulmonary perfusion scintigraphy with total-body imaging demonstrated multiple lung perfusion deficits and abnormal tracer uptake in systemic organs with hepatic radioactivity greater than the kidneys, suggesting the presence of right-to-left shunt and abnormal hepatic hemodynamics. I-123 iodoamphetamine transrectal portal scintigraphy revealed a large portosystemic venous shunt. The follow-up Tc-99m MAA perfusion scans after banding of the patent ductus venosus revealed partial improvement of the perfusion deficits and right-to-left shunt, indicating the possible reversibility of this pulmonary shunt complication.