title: Subclavian steal syndrome: can the blood pressure difference between arms predict the severity of steal?
abstract: OBJECTIVE
  A side-to-side difference in systolic brachial arterial blood pressure is a common finding in subclavian artery stenosis and is frequently used as a screening tool for subclavian steal syndrome (SSS). It was the goal of this retrospective study to investigate the relationship between different vertebral artery waveform types and the side-to-side difference in systolic blood pressure in patients with sonographically proven SSS.
  
  
  METHODS
  The records of 1860 patients from the Neuroultrasound Laboratory between January 2000 and December 2000 were screened for the diagnosis of SSS in the final ultrasound report. In all patients, bilateral brachial arterial blood pressure was measured in a sitting position prior to the ultrasound examination. Vertebral artery waveforms were classified as (1) systolic deceleration, (2) alternating flow, and (3) complete reversal at rest. Blood pressure difference as calculated by normal-side blood pressure minus lesion-side blood pressure was compared with the 3 Doppler waveform types.
  
  
  RESULTS
  SSS was found in 51 of 1860 (2.7%) ultrasonography studies of 49 patients (17 men, 32 women; mean age 65.3 +/- 10.5 years). Two patients (4%) had bilateral SSS. In 3 patients (6%), SSS was related to an innominate artery stenosis. Waveform analysis showed a completely reversed flow in 16 (31%), an alternating flow in 24 (47%), and a systolic deceleration in 11 (22%) cases. Systolic blood pressure difference was significantly higher in the complete reversal and alternating groups than in the systolic deceleration group (P < .001).
  
  
  CONCLUSIONS
  Brachial systolic blood pressure difference is related to the severity of SSS and can be used as a screening tool for SSS. However, it performed better in severe steal than milder steal phenomena.
authors.affiliation: Department of Neurology (I), Chang Gung Memorial Hospital, 123 Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien 833, Taiwan. tengyeowtan@yahoo.com
authors.forename: Teng-Yeow
authors.initials: TY
authors.lastname: Tan
authors.forename: Ulf
authors.initials: U
authors.lastname: Schminke
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Lien
authors.forename: Charles H
authors.initials: CH
authors.lastname: Tegeler
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001132:Arm / Q000098:blood supply; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D013349:Subclavian Steal Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D018608:Ultrasonography, Doppler; D014711:Vertebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology