title: Poststenotic flow and intracranial hemodynamics in patients with carotid stenosis: transoral carotid ultrasonography study.
abstract: OBJECTIVE
  In severe carotid stenosis, blood supply via the poststenotic internal carotid artery (ICA) and collateral pathways determine cerebral perfusion. We investigated whether poststenotic flow on transoral carotid ultrasonography (TOCU) is predictive of cerebral hemodynamics.
  
  
  METHODS
  Eighty-eight patients with unilateral carotid stenosis underwent TOCU to analyze blood flow velocity and poststenotic diameter of the extracranial ICA. Intracranial collaterals and cerebral hemodynamics were assessed with selective angiography and single photon emission CT.
  
  
  RESULTS
  Poststenotic diameter (P <.0001) and velocities (peak systolic velocity [PSV], time-averaged mean velocity [TMV], end-diastolic velocity [EDV]; all P < or = .009) decreased with stenotic severity. Poststenotic diameter was correlated with PSV (r=0.36, P=.0005), EDV (r=0.32, P=.002), and TMV (r=0.39, P=.0001). Poststenotic flow was significantly lower with collateral pathways than without pathways (P < or = .02) and significantly decreased as the number of the collaterals increased (P <.0001). Flow <5 mL/s indicated collaterals (81% sensitivity, 80% specificity). When flow was <5 mL/s, the asymmetry index in the middle cerebral artery (MCA) territory was significantly low during rest (P=.003) and after acetazolamide challenge (P=.006). Poststenotic flow velocity was associated with baseline (P=.007) and postacetazolamide (P=.0009) MCA asymmetry indexes.
  
  
  CONCLUSIONS
  Poststenotic ICA flow measured with TOCU reflects collateral flow and cerebral hemodynamics in patients with severe carotid stenosis. This technique may provide new parameters for screening patients with hemodynamically significant carotid stenosis.
authors.affiliation: Department of Cerebrovascular Disease, Cerebrovascular Center and Clinical Research Institute, National Kyushu Medical Center, Fukuoka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kamouchi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kishikawa
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Okada
authors.forename: Tooru
authors.initials: T
authors.lastname: Inoue
authors.forename: Setsuro
authors.initials: S
authors.lastname: Ibayashi
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Iida
mesh_terms: D000086:Acetazolamide; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery; D003097:Collateral Circulation / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D019160:Endosonography / Q000379:methods*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
chemical_list: D000086:Acetazolamide