title: Microcirculatory hemodynamics and endothelial dysfunction in systemic lupus erythematosus.
abstract: OBJECTIVE
  Impaired flow-mediated dilation (FMD) occurs in disease states associated with atherosclerosis, including SLE. The primary hemodynamic determinant of FMD is wall shear stress, which is critically dependent on the forearm microcirculation. We explored the relationship between FMD, diastolic shear stress (DSS), and the forearm microcirculation in 32 patients with SLE and 19 controls.
  
  
  RESULTS
  DSS was calculated using (mean diastolic velocity x 8 x blood viscosity)/baseline brachial artery diameter. Doppler velocity envelopes from the first 15 seconds of reactive hyperemia were analyzed for resistive index (RI), and interrogated in the frequency domain to assess forearm microvascular hemodynamics. FMD was significantly impaired in SLE patients (median, 2.4%; range, -2.1% to 10.7% versus median 5.8%; range, 1.9% to 14%; P<0.001). DSS (dyne/cm2) was significantly reduced in SLE patients (median, 18.5; range, 3.9 to 34.0 versus median 21.8; range, 14.1 to 58.7; P=0.037). A strong correlation between FMD and DSS, r(s)=0.65, P=0.01 was found. Postischemic RI was not significantly different between the 2 groups; however, there were significant differences in the power-frequency spectrums of the Doppler velocity envelopes (P<0.05).
  
  
  CONCLUSIONS
  These data suggest that in SLE, altered structure and function of the forearm microcirculation contributes to impaired FMD through a reduction in shear stress stimulus.
authors.affiliation: Department of Therapeutics and Pharmacology, Whitla Medical Building, Queens University Belfast, BT9 7BL, Northern Ireland. s.wright@qub.ac.uk
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Wright
authors.forename: Fiona M
authors.initials: FM
authors.lastname: O'Prey
authors.forename: Derrick J
authors.initials: DJ
authors.lastname: Rea
authors.forename: Rick D
authors.initials: RD
authors.lastname: Plumb
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gamble
authors.forename: William J
authors.initials: WJ
authors.lastname: Leahey
authors.forename: Adrian B
authors.initials: AB
authors.lastname: Devine
authors.forename: R Canice
authors.initials: RC
authors.lastname: McGivern
authors.forename: Dennis G
authors.initials: DG
authors.lastname: Johnston
authors.forename: Michael B
authors.initials: MB
authors.lastname: Finch
authors.forename: Aubrey L
authors.initials: AL
authors.lastname: Bell
authors.forename: Gary E
authors.initials: GE
authors.lastname: McVeigh
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D015331:Cohort Studies; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006439:Hemodynamics; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D014463:Ultrasonography; D014655:Vascular Resistance; D014664:Vasodilation