Vasomotor response to CO2 and L-Arginine in patients with severe internal carotid artery stenosis; pre- and post-surgical evaluation with transcranial Doppler.
OBJECTIVE
Carotid artery disease may cause both thromboembolism and cerebral blood flow disturbances, particularly in subjects with impaired hemodynamic compensatory mechanisms. The aim of this study was to evaluate by transcranial Doppler (TCD) the hemodynamic changes induced by CO2 and L-Arginine stimulation in a selected population with severe unilateral carotid stenosis (70-80%), before and after carotid endarterectomy, in order to determine the effect of surgery in the vascular hemodynamics of these patients.


METHODS
We studied 20 subjects (mean age 66.4 years) consecutively admitted to our institute with ischemia and unilateral severe internal carotid artery stenosis (70-80%) detected by Color Doppler. All patients underwent arterial digital subtraction angiography to confirm the ultrasonographic evaluation. TCD was performed bilaterally; blood flow velocity was monitored during CO2 and L-Arginine stimulation both in basal conditions and three months after surgery.


RESULTS
After endarterectomy, mean velocity increased in response to both stimuli with a trend toward statistical significance. A significantly lower reactivity to L-Arginine on the stenotic side was found in the pre-operative phase: this asymmetrical reactivity was no longer observable after carotid endarterectomy.


CONCLUSIONS
We found a statistically significant difference in L-Arginine reactivity in the stenotic side of patients with severe unilateral internal carotid stenosis. This is probably related to an alteration of the endothelium function due to the carotid pathology, since the abnormalities disappeared three months after endarterectomy.
Micieli
G
G
Fondazione C. Mondino, Neurovascular Unit, University of Pavia, Italy. micieli@cpbim1.unipv.it
Bosone
D
D
Zappoli
F
F
Marcheselli
S
S
Argenteri
A
A
Nappi
G
G
D000368:Aged; D001120:Arginine / Q000494:pharmacology*; D001783:Blood Flow Velocity; D001921:Brain / Q000000981:diagnostic imaging; D002245:Carbon Dioxide / Q000494:pharmacology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D002560:Cerebrovascular Circulation; D016894:Endarterectomy, Carotid; D005260:Female; D007839:Functional Laterality; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D011184:Postoperative Period; D012044:Regression Analysis; D014057:Tomography, X-Ray Computed; D018615:Ultrasonography, Doppler, Color; D017585:Ultrasonography, Doppler, Transcranial
D002245:Carbon Dioxide; D001120:Arginine