title: Perfusion augmentation in acute stroke using mechanical counter-pulsation-phase IIa: effect of external counterpulsation on middle cerebral artery mean flow velocity in five healthy subjects.
abstract: OBJECTIVE
  External counterpulsation (ECP) improves coronary perfusion, increases left ventricular stroke volume similar to intraaortic balloon counterpulsation, and recruits arterial collaterals within ischemic territories. We sought to determine ECPs effect on middle cerebral artery (MCA) blood flow augmentation in normal controls as a first step to support future clinical trials in acute stroke.
  
  
  METHODS
  Healthy volunteers were recruited and screened for exclusions. Bilateral 2-MHz pulsed wave transcranial Doppler (TCD) probes were mounted by head frame, and baseline M1 MCA TCD measurements were obtained. ECP was then initiated using standard procedures for 30 minutes, and TCD readings were repeated at 5 and 20 minutes. Physiological correlates associated with ECP-TCD waveform morphology were identified, and measurable criteria for TCD assessment of ECP arterial mean flow velocity (MFV) augmentation were constructed.
  
  
  RESULTS
  Five subjects were enrolled in the study. Preprocedural M1 MCA TCD measurements were within normal limits. Onset of ECP counterpulsation produced an immediate change in TCD waveform configuration with the appearance of a second upstroke at the dicrotic notch, labeled peak diastolic augmented velocity (PDAV). Although end-diastolic velocities did not increase, both R-MCA and L-MCA PDAVs were significantly higher than baseline end-diastolic values (P<0.05 Wilcoxon rank-sum test) at 5 and 20 minutes. Augmented MFVs (aMFVs) were also significantly higher than baseline MFV in the R-MCA and L-MCA at both 5 and 20 minutes (P<0.05).
  
  
  CONCLUSIONS
  ECP induces marked changes in cerebral arterial waveforms and augmented peak diastolic and mean MCA flow velocities on TCD in 5 healthy subjects.
authors.affiliation: Comprehensive Stroke Center, University of Alabama, Birmingham, AL 35249-3280, USA. annealex@uab.edu
authors.forename: Anne W
authors.initials: AW
authors.lastname: Alexandrov
authors.forename: Marc
authors.initials: M
authors.lastname: Ribo
authors.forename: Ka Sing
authors.initials: KS
authors.lastname: Wong
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Sugg
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Garami
authors.forename: Jill T
authors.initials: JT
authors.lastname: Jesurum
authors.forename: Baxter
authors.initials: B
authors.lastname: Montgomery
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Alexandrov
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015908:Counterpulsation / Q000295:instrumentation / Q000379:methods; D006801:Humans; D020768:Middle Cerebral Artery / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology* / Q000628:therapy; D017585:Ultrasonography, Doppler, Transcranial