Monitoring direction of vertebral artery blood flow by Doppler shift ultrasound in patients with suspected "subclavian steal'.

A significant subclavian or innominate artery obliteration may cause reversal of flow in the ipsilateral vertebral artery causing vertebro-basilar ischaemia with cerebral symptoms, called the subclavian steal syndrome. Until recently, angiography was the only method of diagnosing a subclavian steal. In the present study, a non-invasive technique (Directional Doppler ultrasound) was used to determine the direction of flow in the vertebral arteries. The study was carried out on 22 patients referred with suspected subclavian could be identified bilaterally by the Doppler ultrasound technique, which also revealed unilateral retrograde in twenty and bilateral antegrade (= normal) vertebral artery blood flow in two patients. These findings were verified in all patients by aorto-cervical angiography. Seven of the patients then had their subclavian or innominate artery reconstructed. Postoperatively a new Directional Doppler ultrasound examination then showed bilateral normal (= antegrade) vertebral artery blood flow. The used non-invasive technique is shown to have high reliability and may be used to screen patients suspected of having subclavian steal pre-angiographically and preoperatively. The method is also of value for the post-operative control.