Carotid endarterectomy when the distal internal carotid artery is small or poorly visualized

This is a report of the operative findings and results of carotid endarterectomy (CEA) when the conventional arteriogram demonstrates an internal carotid artery with a high-grade origin stenosis and a small or poorly visualized distal extracranial segment with an apparent diameter of 2 mm or less.

Eighteen CEA were performed on 17 patients with this preoperative finding and patent common and external carotid arteries. The indications for CEA were transient ischemia in seven patients, completed minor stroke in five and amaurosis fugax in four patients. One patient had bilateral findings and global cerebral ischemic symptoms.

At CEA 16 internal carotid arteries had atherosclerotic very high-grade origin stenosis, and two had chronic occlusion. Ten of the 16 open arteries had true external diameters of 4 mm or more. Of these, seven were normal above the stenosis, two had a long, trailing intraluminal thrombus that was removed, and one had high-grade distal stenosis. Of the six arteries with true diameters of 3 mm or less (hypoplastic), two had a thick fibrotic wall. The carotid stump back pressure for the 16 open internal carotid arteries was 56 +/- 15 mm Hg (mean +/- SD). This was significantly higher than the 39 +/- 14 mm Hg back pressure measured in 1016 arteries without a string sign (p < 0.001). There was one 30-day postoperative death after a stroke. There was no systemic or neurologic morbidity. Post-CEA duplex scans demonstrated eight normal, five mildly stenotic, and five occluded internal carotid arteries. Two of the occlusions were found at CEA and the other three occluded arteries had low flow after CEA, two of which were hypoplastic and the other had a distal stenosis.

Patients with symptoms with these findings on arteriograms should undergo CEA. However, the success of CEA in this setting depends on the internal carotid artery anatomy and disease, which is difficult to determine before CEA. Patients with a truly normal extracranial internal carotid artery have an excellent probability of a successful CEA, but this is not the case when the artery is small or fibrotic. Low internal carotid artery flow after a technically satisfactory CEA is a harbinger of thrombosis and should be managed by internal carotid artery ligation and external CEA.