title: Cerebrovascular response time to a breath-holding challenge.
abstract: BACKGROUND
  To evaluate the timecourse of cerebrovascular reserve response to breath-holding.
  
  
  METHODS
  Using simultaneous bilateral transcranial Doppler (TCD) recordings from the MCA during a breath-holding challenge, we measured the time interval between baseline and peak blood flow velocity values in 25 patients with critical unilateral internal carotid artery (ICA) stenosis (> 85% lumen diameter reduction), in 9 patients with a non-critical (70-85%) ICA-stenosis and in 27 normal controls.
  
  
  RESULTS
  Normal controls and patients with non-critical stenosis reached peak MCA velocities on both sides almost simultaneously. For the patients with critical stenosis the peak response time ipsilateral to the stenosis was delayed 2.40 +/- 3.43 sec compared to the opposite side. This delay resolved after carotid endarterectomy.
  
  
  CONCLUSIONS
  In response to a breath-holding challenge unilateral critical ICA stenosis is associated with a significant ipsilateral prolongation of the rise time from baseline to peak MCA velocity.
authors.affiliation: Klinik und Poliklinik für Neurologie, Universitatsklinikum Carl Gustav Carus der Technischen Universität, Dresden, Germany. gahn@rcs.urz.tu-dresden.de
authors.forename: G
authors.initials: G
authors.lastname: Gahn
authors.forename: U
authors.initials: U
authors.lastname: Hallmeyer-Elgner
authors.forename: S
authors.initials: S
authors.lastname: Becker
authors.forename: K M
authors.initials: KM
authors.lastname: Barrett
authors.forename: R H
authors.initials: RH
authors.lastname: Ackermann
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002343:Carotid Artery, Internal / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D002560:Cerebrovascular Circulation; D003097:Collateral Circulation; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012119:Respiration; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial