Subclavian steal syndrome

Case contributed by Dr Rahul Chivate


Pre-operative evaluation for CABG. Patient had episode of a stroke 2 months prior.

Patient Data

Age: 65 years
Gender: Male

Ultraound Color Doppler of vertebral arteries show a complete reversal of flow on right side. The vein and artery show blue color as flow is retrograde in same direction. Single sharp systolic is noted. The left vertebral artery shows normal antegrade flow with artery in red and vein in blue color.


CT angiography on same patient shows a tight stenosis in the right subclavian artery proximal to origin of vertebral artery. The origin of left vertebral artery and its proximal segment is occluded and shows no IV contrast fill. The distal left vertebral artery is supplied by collateral vessels arising from left subclavian artery.

Case Discussion

In this case there is a complete reversal of flow in right vertebral artery with sharp single systolic peak. There are biphasic waveforms within the distal subclavian arteries. The origin is not visualized. The left vertebral artery shows antegrade flow with a normal waveform and velocity. A high grade stenosis was confirmed by CT angiography. There is also a complete occlusion of left vertebral artery artery from its origin to the V1 segment. The V2 segment is supplied by collaterals arising from left subclavian artery.

There are characteristic flow change in the right vertebral artery flow due to stenosis in the ipsilateral subclavian artery proximal to origin of vertebral artery. This stenosis produces a pressure gradient between cerebral circulation and subclavian artery. The severity of stenosis is also reflected in the vertebral artery Doppler.

  • 45% stenosis- Pre- bunny waveform pattern, two systolic peak with sharp first and rounded second peak  with preservation of antegrade flow.
  • 55% stenosis-Bunny waveforms producing a deeper cleft between two systolic peaks.
  • 80% stenosis there will be to and fro bidirectional flow. Initial antegrade followed by retrograde flow.

Complete reversal of flow in VA is caused by severe stenosis in proximal subclavian artery.

PlayAdd to Share

Case information

rID: 25065
Published: 2nd Oct 2013
Last edited: 1st Mar 2016
System: Vascular
Inclusion in quiz mode: Included

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.