Discussion
This radiograph shows severely dilated pulmonary arteries. The differential for this finding includes pulmonary hypertension, flow abnormalities from shunting or valvular disease, and connective tissue diseases, among others. This a young patient with Eisenmenger Syndrome, a condition resulting from a longstanding uncorrected left-to-right shunt. The shunt causes pulmonary hypertension, which eventually becomes so severe that the direction of flow through the shunt reverses resulting in significant hypoxemia.
The exam is otherwise normal.