Critical Analysis of Vertebral Artery Flow Patterns/Subclavian Steal Detected by Cerebrovascular Duplex Ultrasound Exams and Its Clinical Implications.

Publication/Presentation Date



BACKGROUND: The prevalence of subclavian steal (defined as retrograde/bidirectional vertebral artery flow) in the general population and in patients undergoing cerebrovascular duplex ultrasound (CDUS) exams is variable. This is the largest study to date to analyze the incidence of duplex-suggested subclavian steal in 5615 CDUS exams over a one year period and to examine its clinical implications.

PATIENT POPULATION AND METHODS: All consecutive CDUS exams performed over a one year period were examined for the presence of subclavian steal. Indications of testing, presence of posterior cerebral circulation/subclavian steal symptoms, and any interventions for subclavian steal were analyzed.

RESULTS: 171/5,615 (3.1%) were found to have subclavian steal (duplex-suggested). 117 (2.1%) had retrograde flow and 54 (1%) had bidirectional flow. 104/171 (60.8%) were left sided. Indications for CDUS were: post CEA/CAS surveillance in 39 patients (22.8%), surveillance for progression of carotid stenosis in 76 patients (44.4%), TIA/stroke in 26 patients (15%), asymptomatic screening/carotid bruit in 18 patients (10.5%) and isolated posterior cerebral circulation symptoms in 12 patients (7%). 63% of patients had associated >50% carotid stenosis. The mean arm Doppler pressure gradient was 32.2 mmHg for asymptomatic patients vs 37mmHg for patients with posterior circulation symptoms (p=.3254). There were significant differences between the mean systolic arm pressure for patients with retrograde vs antegrade vs bidirectional flow (105 mmHg vs 146 vs 134, p50% subclavian stenosis or occlusion (100/117 had subtotal/total occlusion) except for one patient. Meanwhile, 52/54 patients with bidirectional flow had >50% subclavian stenosis (6/54 with subtotal/total occlusion) while two patients were normal/

CONCLUSIONS: The incidence of subclavian steal in patients who undergo CDUS is relatively rare. Most of these patients are asymptomatic and can be treated conservatively with only a few percentage who may need intervention for disabling symptoms with good symptom resolution.




Medicine and Health Sciences




Department of Medicine

Document Type