Right subclavian steal
Referral for investigation of markedly lower right brachial artery pressure compared to the left. The patient is a long-term smoker,
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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.
Occlusion of the right subclavian artery at its origin caused a right-sided subclavian steal and decreased pressures within the right arm arteries.