The vertebral bunny waveform: an early manifestation of the subclavian steal syndrome.

A 69-year-old man was referred to the radiology department for pre - operative duplex evaluation of the carotid and vertebral arteries. The patient was scheduled for coronary artery bypass graft surgery. Duplex examination showed diffuse intimal thickening and bilateral non-stenotic, small heterogeneous plaque formation at the level of the carotid bifurcation. The flow pattern at the left vertebral artery showed a sharp decline during midsystole and a subsequent rounded second systolic peak, resembling a rabbit in profile (Fig. A). We performed a CT angiography which showed the presence of a stenosis of 50% at the ostium of the left subclavian artery (Fig. B and C arrows).