Critical Analysis Of Vertebral Artery Flow Patterns/Subclavian Steal Syndrome Detected By Cerebrovascular Duplex Ultrasound Exams And Its Clinical Implications
Ali F. AbuRahma, MD1, Adrian Santini, MD1, Matthew Beasley, MD1, Meghan Davis, MD1, Mazen Roshdy, MD1, Andrew Lee, MD1, Kimberly Seal, DO1, L. Scott Dean, PhD, MBA2, Elaine Davis, RN, Ed.D2.
1West Virginia University-Charleston Division, Charleston, WV, USA, 2CAMC Institute for Academic Medicine, Charleston, WV, USA.
Background: The prevalence of subclavian steal (SS) in the general population and in patients undergoing cerebrovascular duplex ultrasound (CDUS) exam is variable. This is the largest study to date to analyze the incidence of subclavian steal in 5615 CDUS exams over a 1 year period and to examine its clinical implications. Patient populations/methods: All consecutive CDUS exams were examined for the presence of SS. Indications of testing, the presence of posterior cerebral circulation (PCC)/SS symptoms and any interventions were analyzed. Results: 171/5615 (3.1%) were found to have SS. 117 (2.1%) had retrograde flow and 54 (1%) had bidirectional flow. 61%) were left sided. Indications for CDUS were: post CEA/CAS surveillance in 23%), surveillance for progression of carotid stenosis in 44%, TIA/stroke in 15%, asymptomatic screening/carotid bruit in 11% and isolated PCC symptoms in 7%. When patients were analyzed for the presence of associated PCC/SS symptoms or arm claudications, 119 (69.6%) had no symptoms while 52 (30.4%) had symptoms (35 with PC symptoms and 23 arm claudications). 63% of patients had associated >50% carotid stenosis. There was significant differences between the mean systolic arm pressure for patients with retrograde flow vs antegrade flow vs bidirectional flow (105 mmHg vs 146 vs 134, p<.0001). All patients with retrograde flow had >50% subclavian stenosis or occlusion (100/117 had subtotal/total occlusion) except for 1 patient. Meanwhile, 52/54 patients with bidirectional flow had >50% subclavian stenosis (p<.0001). Overall, 26/171 patients (15.2%) had interventions for disabling symptoms: 16 of which were subclavian PTA/stenting (2 of which were a combined innominate/subclavian stenotic lesions), 4 had carotid subclavian bypass and 6 had CEA (for associated severe carotid stenosis). 11/26 of all interventions were for disabling arm claudications, and only 10/171 patients (5.8%) were done for disabling PCC symptoms with complete resolution of symptoms in all except one. At a late follow-up with a mean of 18 mos., there was no late major stroke with only 2 lacunar infarcts (not subclavian steal related). There was also 7 late deaths, none were stroke related. Conclusions: The incidence of subclavian steal in patients who undergo CDUS is rare. Most are asymptomatic and can be treated conservatively with only few percentage who might need intervention for disabling symptoms with good symptom resolution.
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