Impaired clearance of microemboli and cerebrovascular symptoms during carotid stenting procedures.
BACKGROUND
Transcranial Doppler monitoring shows a high prevalence of microemboli during carotid artery stenting (CAS); however, the occurrence of cerebrovascular symptoms (CVSs) does not seem to be related to the microembolic load.


OBJECTIVE
To evaluate embolic and hemodynamic transcranial Doppler monitoring findings and their relationships with the occurrence of procedural CVSs. Patients Fifty-four patients who had carotid stenosis of more than 70% underwent a total of 57 CAS procedures during transcranial Doppler monitoring of mean blood flow velocity and microembolic signals in the middle cerebral artery. The occurrence of transient ischemic attack, transient monocular blindness, and stroke during the CAS procedure was considered CVSs.


RESULTS
Nine (15.8%) of the 57 patients had CVSs during the procedure (ie, 6 patients with transient ischemic attack, 1 with transient monocular blindness, 1 with a minor stroke, and 1 with a major stroke). The mean blood flow velocity median values were statistically significantly lower (P < .001) in the group of 9 patients with CVSs (36 cm/s; interquartile range, 32.3-38.5) compared with the 48 without CVSs (48 cm/s; interquartile range, 41.5-52). The median number of isolated microembolic signals was similar in the 2 groups (72; interquartile range, 66-81 vs 75; interquartile range, 67-83.5). The median number of microembolic signal showers (clusters of too many signals to be counted separately in one cardiac cycle) presented a nonsignificant prevalence in the patients with CVSs (9; interquartile range, 7.5-11.2) compared with the ones without CVSs (8.2; interquartile range, 7-9).


CONCLUSIONS
The low flow velocity in the middle cerebral artery may impair the clearance of the microembolic load and should be considered a precursor of CVSs during the CAS procedure.
Orlandi
Giovanni
G
Department of Neuroscience, University of Pisa, Pisa, Italy. g.orlandi@neuro.med.unipi.it
Fanucchi
Simona
S
Gallerini
Simone
S
Sonnoli
Chiara
C
Cosottini
Mirco
M
Puglioli
Michele
M
Sartucci
Ferdinando
F
Murri
Luigi
L
D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D016893:Carotid Stenosis / Q000601:surgery*; D002560:Cerebrovascular Circulation / Q000502:physiology; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology; D019635:Neurosurgical Procedures / Q000009:adverse effects; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D015607:Stents / Q000009:adverse effects*; D020521:Stroke / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D017585:Ultrasonography, Doppler, Transcranial; D014656:Vascular Surgical Procedures / Q000009:adverse effects*