Microvascular versus macrovascular cerebral vasomotor reactivity in patients with severe internal carotid artery stenosis or occlusion.
OBJECTIVE
In patients with severe internal carotid artery steno-occlusive lesions (ISOL), impaired cerebrovascular reactivity (CVR) is predictive of future ischemic stroke (IS) or transient ischemic attack (TIA). Therefore, the evaluation of CVR in ISOL patients may be a means to evaluate the risk for IS/TIA and decide on an intervention. Our aim was (1) to explore the feasibility of concurrent near-infrared spectroscopy (NIRS-DOS), diffuse correlation spectroscopy, and transcranial Doppler for CVR assessment in ISOL patients, and (2) to compare macrovascular and microvascular CVR in ISOL patients and explore its potential for IS/TIA risk stratification.


METHODS
Twenty-seven ISOL patients were recruited. The changes in continuous microvascular and macrovascular hemodynamics upon acetazolamide injection were used to determine CVR.


RESULTS
Oxyhemoglobin (HbO2, by near-infrared spectroscopy), microvascular cerebral blood flow (CBF, by diffuse correlation spectroscopy) and CBF velocity (by transcranial Doppler) showed significant increases upon acetazolamide injection in all subjects (P < .03). Only macrovascular CVR (P = .024) and none of the microvascular measures were significantly dependent on the presence of ISOL. In addition, while CBF was significantly correlated with HbO2, neither of these microvascular measures correlated with macrovascular CBF velocity.


CONCLUSIONS
We demonstrated the simultaneous, continuous, and noninvasive evaluation of CVR at both the microvasculature and macrovasculature. We found that macrovascular CVR response depends on the presence of ISOL, whereas the microvascular CVR did not significantly depend on the ISOL presence, possibly due to the role of collaterals other than those of the circle of Willis. The concurrent microvascular and macrovascular CVR measurement in the ISOL patients might improve future IS/TIA risk assessment.
ICFO- Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860, Castelldefels, Barcelona, Spain. Electronic address: peyman.zirak@icfo.es.
Peyman
P
Zirak
Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Raquel
R
Delgado-Mederos
Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Lavinia
L
Dinia
Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Joan
J
Martí-Fàbregas
ICFO- Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860, Castelldefels, Barcelona, Spain.
Turgut
T
Durduran
D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation; D055806:Microvessels; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism*; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods; D014666:Vasomotor System
D010108:Oxyhemoglobins
Diffuse correlation spectroscopy; cerebrovascular reactivity; internal carotid artery stenosis; near-infrared spectroscopy