Figure 2

A patient with bilateral bidirectional Glenn anastomoses and central branch pulmonary artery stenosis with abnormal streaming of their systemic venous return. With a lower extremity injection, on first pass time-resolved contrast enhanced magnetic resonance angiography, only the right Y-arm is opacified and the left Y-arm is not seen (a), while on a later phase when the left Glenn fills, the left Y-arm is seen to fill retrograde (b). Phase contrast imaging across the Y-arms (c) demonstrates that flow is in opposite directions (antegrade in the right arm and retrograde in the left arm).