Comparison of intraoperative and postoperative duplex ultrasound for carotid endarterectomy

Intraoperative (IO) duplex ultrasound (DU) is used to identify correctable technical defects at the time of carotid endarterectomy (CEA). Postoperative (p.o.) DU is used to evaluate recurrent or residual stenosis. We compared IO and p.o. DU to determine the value and significance of these studies in the management of patients undergoing CEA. We performed completion IO DU following CEA and p.o. DU a mean of 8 weeks after surgery in 78 patients. IO studies were performed by the operating surgeon and p.o. studies were performed in an accredited vascular laboratory. Peak systolic velocity (PSV) was measured in the internal carotid (ICA), external carotid, and common carotid (CCA) arteries. The criteria used for an abnormal study were an ICA PSV > 150 cm/sec and a ratio of ICA to CCA PSVs(ICA/CCA) > 3.0. Completion angiograms were also performed on all patients intraoperatively. Technical defects identified on DU or angiogram were corrected whenever possible. From our results, we concluded that in many patients, early p.o. DU will demonstrate an elevated ICA PSV compared to the IO PSV. If the ICA/CCA remains normal, this increase is unlikely to represent a clinically relevant recurrent or residual stenosis. A postoperative ICA/CCA ratio > 3.0 may be a more reliable indicator of significant stenosis and a lesion that is likely to progress or occlude than PSVs alone.