Postoperative carotid restenosis due to neointimal fibromuscular hyperplasia. Clinical, angiographic, and pathological findings.

Following endarterectomy, stenosis can recur in 0.2-3.6% of carotid arteries due to neointimal fibromuscular hyperplasia (NFH). Angiographically, NFH is manifested as concentric, alternating areas of normal tissue and smooth narrowing which are seen as pale, glistening, nonulcerated plaques on gross examination. Histological study demonstrates proliferation of smooth muscle cells, disruption of the internal elastic lamina, and often discontinuity of the endothelium. Calcium and cholesterol deposits are absent. The cause of the lesion is unknown, and surgical management is frequently difficult.