Diagnostic ultrasound ( PDFDrive )

942 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
A
B
J
I
E
C
D
E
FIG. 26.36 CCA Occlusion Causes Abnormal ICA Waveform. (A) Antegrade tardus-parvus waveform is seen in an ICA distal to a CCA
occlusion. (B) Retrograde ECA low with a tardus-parvus waveform caused by collateral low from the contralateral ECA to supply the ipsilateral
ICA distal to a CCA occlusion. (C) Color Doppler image shows antegrade ECA low (E) with an ECA branch (arrow) and retrograde ICA low (I). J,
Internal jugular vein. (D) Spectral Doppler image shows high-resistance retrograde right ICA low. (E) High-resistance antegrade low in the right
ECA distal to a CCA occlusion.
and carotid ultrasound have discordant results or they are
inadequate. 176-180 Other studies support the use of carotid ultrasound
alone before endarterectomy. 177,178,181-185 Numerous studies
show that more than 90% of surgical candidates can be adequately
screened using clinical assessment and ultrasound alone. However,
in suspected aortic arch proximal vessel disease or in cases of
suspected complete occlusion, some practitioners still advocate
preoperative angiography.
Postoperative Ultrasound
he carotid artery ater endarterectomy (post-CEA) demonstrates
many characteristic features 186,187 (Fig. 26.37). A discrete wedge
between the normal I-M complex and the endarterectomized
surface is frequently seen, as are periodically spaced echogenic
sutures. he absent I-M complex has also been shown to regrow.
One study showed that 6% of CEA patients had carotid laps,
residual moderate to moderately severe stenoses, or occluded
ECAs. 188 Two of these patients with postoperative abnormalities
on ultrasound sustained perioperative stroke. Patients without
defects on the postoperative ultrasound had no perioperative
sequelae or need for a repeat of procedures. Patients with preoperative
stenoses greater than 75% have a greater risk for residual
stenoses. Ultrasound appears useful in the symptomatic postoperative
population, but its role in the asymptomatic patient population
is debatable. 189 Routine follow-up with ultrasound every 6 months
ater CEA for 2 years and then annually or possibly just once
12 months ater CEA has been recommended; however, more
research needs to be done. 190,191
Carotid Artery Stents and Revascularization
Percutaneous transluminal carotid artery stenting (CAS) in
association with carotid angioplasty is becoming an increasing
popular and common means of carotid revascularization. Between
1998 and 2004, the incidence of CEA decreased 17%, whereas