Right subclavian steal

Arm artery pressures as follows:                          Right        Left

                                                                Brachial      140           177 mmHg

                                                                Radial         134           172

                                                                Ulnar           129           163

• There is echogenic plaque or embolus at the origin of the right subclavian artery (arrow).
• Retrograde flow of about 115cm/s was observed in the right vertebral artery.
• High velocity (206 cm/s) antegrade flow was demonstrated in the left vertebral artery. Velocity was nearly twice that in the right vertebral artery. This is likely due to collateralisation.
• Retrograde flow was seen in the right subclavian artery proximal to the vertebral artery origin.
• No flow was demonstrated from the brachiocephalic artery into the right subclavian artery (color Doppler). A terminal thump was seen distal to the occlusion from the retrograde flow in the proximal right subclavian artery (spectral Doppler).

To conclude, there appears to be occlusion of the right subclavian artery at its origin with collateralisation of the vertebral arteries. Retrograde flow in the right vertebral artery supplied the right arm.