title: Dynamic cerebral autoregulation in carotid stenosis before and after carotid stenting.
abstract: BACKGROUND
  Impaired dynamic cerebral autoregulation (DCA) has been shown in patients with severe (> or =70%) internal carotid artery (ICA) stenosis, but DCA in moderate (50% to 69%) ICA stenosis, especially its response to carotid revascularization, has rarely been reported. Our study aimed to characterize DCA in severe and moderate ICA stenosis before and after carotid stenting.
  
  
  METHODS
  This study included 21 patients with ICA stenosis > or =50% who received carotid stenting. Data of arterial blood pressure and cerebral blood flow velocity of the middle cerebral artery, measured by transcranial Doppler, were collected for 10 minutes < or =24 hours before and after stenting. The DCA index, represented as aMx, was assessed by calculating the Pearson product-moment correlation coefficient of spontaneous arterial blood pressure and cerebral blood flow velocity fluctuations. The relationship between aMx and stenotic severity and also alternations of aMx before and after stenting were assessed.
  
  
  RESULTS
  Carotid stenting was effective to improve the DCA in the stenting side but not in the contralateral nonstenting side. In considering individual ICAs, the average aMx (mean +/- SD) increased significantly from ICA stenosis <50% (0.117 +/- 0.091) to 50% to 69% (0.349 +/- 0.144), 70% to 99% (0.456 +/- 0.147), and total occlusion (0.557 +/- 0.210; P < .05, P < .01, and P < .01, compared with 50% to 69%, 70% to 99%, or total occlusion with <50% stenosis). The correlation between the degree of ICA stenosis and the aMx was also significant (r = 0.693, P < .005). The aMx improved significantly in the stented side after carotid stenting in both moderate and severe ICA stenosis, and this finding was not affected by age, sex, risk factors, or clinical symptoms.
  
  
  CONCLUSIONS
  In addition to patients with severe carotid stenosis, patients with moderate carotid stenosis may also have impaired DCA that can be restored after carotid stenting.
authors.affiliation: Stroke Center and Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Sung-Chun
authors.initials: SC
authors.lastname: Tang
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Huang
authors.forename: Jiann-Shing
authors.initials: JS
authors.lastname: Shieh
authors.forename: Sheng-Jean
authors.initials: SJ
authors.lastname: Huang
authors.forename: Ping-Keung
authors.initials: PK
authors.lastname: Yip
authors.forename: Jiann-Shing
authors.initials: JS
authors.lastname: Jeng
mesh_terms: D000368:Aged; D000800:Angioplasty, Balloon; D001783:Blood Flow Velocity; D001921:Brain / Q000503:physiopathology*; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D015999:Multivariate Analysis; D015607:Stents; D017585:Ultrasonography, Doppler, Transcranial