[Impaired cerebral autoregulation in asymptomatic patients with carotid artery stenosis: comparison of acetazolamide-SPECT and transcranial CO(2)-dopplersonography].
OBJECTIVE
The indication for operation in patients with asymptomatic high-grade carotid artery stenosis is still under debate. Since impaired cerebrovascular autoregulation is associated with an increased risk for ischaemic events, assessment of cerebral vascular reactivity might be a valuable selection criterion for surgery. The aim of our study was therefore to evaluate the incidence of impaired autoregulation in asymptomatic patients with acetazolamide-single photon emission computed tomography (ACZ-SPECT) and transcranial CO (2)-dopplersonography (CO (2)-TCD). Furthermore, both methods were compared in regard to results and clinical practicability.


METHODS
In 42 patients with high-grade (> 70 %) asymptomatic carotid artery stenosis, cerebral perfusion and vascular reactivity were assessed with resting and ACZ-enhanced SPECT scans. In 31 of these patients the CO (2) reactivity of cerebral perfusion was determined by TCD and expressed as normalized autoregulation reserve (NAR).


RESULTS
Cerebral perfusion was decreased in 14.3 %. In ACZ-SPECT 26 % and in CO (2)-TCD 28 % revealed an impaired vascular reactivity. Conformity of both methods was high (kappa = 0.93). TCD was superior in practicability, but only applicable in 81 % due to a missing temporal bone window for insonation.


CONCLUSIONS
In accordance ACZ-SPECT and CO (2)-TCD could detect impaired vascular reactivity in a quarter of asymptomatic patients. Both TCD and SPECT could be of value for preoperative selection in this group of patients, whereby sonography is recommended for daily diagnostic work-up.
Engelhardt
M
M
Klinik für Gefäss- und Thoraxchirurgie, Zentralklinikum Augsburg, Augsburg. m-engelhardt@web.de
Pfadenhauer
K
K
Zentner
J
J
Grimmer
S
S
Wachenfeld-Wahl
C
C
Heidenreich
P
P
Loeprecht
H
H
Wölfle
K D
KD
D000086:Acetazolamide; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D002245:Carbon Dioxide; D002343:Carotid Artery, Internal / Q000503:physiopathology / Q000601:surgery*; D016893:Carotid Stenosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D003097:Collateral Circulation / Q000502:physiology; D016894:Endarterectomy, Carotid; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D015899:Tomography, Emission-Computed, Single-Photon; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000502:physiology
D002245:Carbon Dioxide; D000086:Acetazolamide