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Background and Purpose: Continuous-wave (cw)-Doppler sonography is a wellestablished noninvasive method
for examining the extracranial vessels. It is extremely rare for an acute ischemic
event to occur during cw-Doppler sonography of carotid stenosis. However, no data
are available concerning the influence of mechanical stress connected with this procedure
on the emboli rate distal to the stenosis.
Methods: The study involved 46 patients (28 men, 18 women) aged 66±10 years with an unilateral
moderate (n=10) or severe (n=36) stenosis of the internal carotid artery (ICA). Twenty
patients had a symptomatic stenosis and the remaining 26 were asymptomatic. Patients
with other embolic sources, such as atrial fibrillation or mechanical heart valves,
were excluded. All patients underwent bilateral emboli detection of the middle cerebral
artery for a period of 29±8 minutes. In a second step, emboli detection (5±1 minutes)
was performed simultaneously with cw-Doppler sonography of the carotid stenosis. Results: Seven of 46 patients (15%) had a median emboli rate of 5 emboli per hour distal
to the carotid stenosis before the procedure. During cw-Doppler sonography of the
carotid stenosis, 6 patients (13%) had a median emboli rate of 14 emboli per hour
without clinical symptoms of cerebral ischemia. One patient had no change of the emboli
rate and 2 patients showed a nonsignificant increase in emboli rate during cw-Doppler
sonography. Three patients had no emboli before cw-Doppler sonography, but between
12 and 15 emboli per hour during the extracranial examination (P<.001). Conclusions: It must be presumed that patients with severe stenoses of the ICA represent a subgroup
with fragile atheromatous plaques, which are more vulnerable to mechanical stress.
The observations support the hypothesis that mechanical stress associated with routine
ultrasound examinations of carotid stenosis may, in rare cases, evoke asymptomatic
artery-to-artery embolism.
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Article info
Publication history
Accepted:
November 24,
1997
Received:
May 22,
1997
Identification
Copyright
© 1998 National Stroke Association. Published by Elsevier Inc.
