The morphology of the carotid artery after uncomplicated endarterectomy

Endarterectomy of the carotid sinus is one of the most frequent vascular operations. Until now, however, few details have been reported on the characteristic features of the disobliteration site during uncomplicated postoperative progress. Full histological and morphometric investigation was performed on the bifurcation of the carotid artery of 23 autopsies with previous endarterectomy, in some cases on both sides. The postoperative interval was of up to 10 years duration (early phase up to 6 months postoperatively 15x, late phase 14x). The findings were compared with surgical specimens of 9 restenoses. The reconstruction of an inner layer (so-called neointima) and the smoothing of the marginal layers of the disobliteration site takes place rapidly through the proliferation of smooth muscle cells from the remaining portions of the media. The narrower this remaining portion of the media, the greater the width achieved by these "neo-intima" (p < 0.05). There is occasional formation of elastic lamellae, similar to an elastic internal lamina, close to the luminal surface. Furthermore, in some cases the reconstruction of an intimal thickening (fibrous ridge) characteristic of the carotid bifurcation was observed at the entrance to the carotid sinus; this can be assessed as an indication that flow irregularities apparently persist postoperatively at this location. In the late phase, intramural calcification and new sclerotic plaques usually occur; these plaques closely resemble those of surgically removed restenoses. The distribution of plaques of this kind is largely congruent with the pattern of plaques in asymptomatically diseased carotid arteries. Thus, following endarterectomy in the carotid sinus, sclerotic plaques recur even during an uncomplicated course subsequent to reparative processes; as with the natural history of sclerotic plaques at the carotid bifurcation, this recurrence seems to be largely determined by hemodynamic factors.