http://stroke.ahajournals.org/content/39/10/2760.short
Abstract
Background and Purpose—
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 less than 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 less than 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.
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