title: Interpretation of TCD spectral patterns detected during carotid artery stent interventions.
abstract: OBJECTIVE
  To classify transcranial Doppler (TCD) spectral patterns and analyze the significance of the patterns in the determination of hemodynamic alterations occurring during filter-protected carotid artery stent (CAS) procedures.
  
  
  METHODS
  Data on middle cerebral artery (MCA) monitoring and post-CAS diffusion weighted magnetic resonance imaging (DWMRI) were reviewed for 53 patients (45 men; mean age 67.6 ± 8.3 years) who underwent TCD evaluation before CAS and TCD monitoring during the procedure. TCD spectral patterns were classified according to the hemodynamic changes that occurred after different portions of the CAS procedures. The relationships among the spectral patterns and the frequency and location of new DWMRI lesions were analyzed.
  
  
  RESULTS
  TCD spectral changes were classified into 4 patterns: (1) microemboli signals (53, 100%), (2) right-left collateral signals (31/53, 58%), (3) spectral suppression after balloon inflation (31/44, 70%), and (4) continuous spectral suppression after balloon removal (4/44, 9%). Even though microembolic signals were frequently observed during CAS, the new DWMRI lesions were more frequently observed outside of the cerebral territory (78%) rather than in the territory ipsilateral to CAS (47%). The presence of right-left collaterals was related to less severe balloon-related spectral suppression on ipsilateral MCA (p<0.05). Continuous spectral suppression appeared after stent deployment and balloon dilation and was immediately reversed after removal of the filter device.
  
  
  CONCLUSIONS
  The spectral patterns classified in the present study may prove useful in anticipating CAS procedure-related hemodynamic alterations. Close hemodynamic observation using these spectral patterns could be helpful in preventing serious complications during CAS.
authors.affiliation: Department of Neurology, Chungnam National University Hospital and College of Medicine, Daejeon, South Korea.
authors.forename: Hye Seon
authors.initials: HS
authors.lastname: Jeong
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Song
authors.forename: Jae-Hwan
authors.initials: JH
authors.lastname: Lee
authors.forename: Si Wan
authors.initials: SW
authors.lastname: Choi
authors.forename: Jei
authors.initials: J
authors.lastname: Kim
mesh_terms: D000368:Aged; D017130:Angioplasty / Q000009:adverse effects* / Q000295:instrumentation*; D016893:Carotid Stenosis / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D002560:Cerebrovascular Circulation; D003097:Collateral Circulation; D057505:Embolic Protection Devices; D005260:Female; D006439:Hemodynamics; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D056910:Republic of Korea; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015607:Stents; D013997:Time Factors; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial