In addition, in cases of subclavian steal from the vertebral artery, there is a graded system showing a progressive change in the ipsilateral vertebral artery waveform. Grade I lesions demonstrate ...

Vertebral arteries: 4–12mL; Aortic arch injection [4 vessel study]: 20–50mL; max 150mL. Intra-arterial (Peripheral arteriography): Subclavian or femoral artery: 5–40mL; Aortic bifurcation ...

and there is also a hemodynamically significant lesion in the proximal left subclavian artery. Flow reversal can occur in both the vertebral and internal mammary artery, or can be isolated to ...