Electron Microscopic Luminal Surface Characteristics of Carotid Plaques

Abstract

Luminal surface characteristics in symptomatic and asymptomatic patients with carotid artery disease have not been thoroughly evaluated. Carotid artery atherosclerotic plaques were subjected to a scanning electron microscopic (EM) examination to determine plaque surface morphology. Correlation of clinical presentation, including clinical symptoms, risk factors, and macroscopic plaque appearance, with plaque EM appearance was analyzed for 16 patients. Differences between symptomatic and asymptomatic patients and differences among plaque characteristics were analyzed by use of the two-tailed Fisher's Exact Test or the Mann-Whitney U statistic. Two predominant types of surface inhabitants were noted, fibrin/red blood cell clumps and collagen and calcium matrix. In all symptomatic patients (n=12) luminal surface fibrin was noted (P=0.007), and 83% of these symptomatic patients had red blood cell clumps (P=0.06). Among asymptomatic individuals (n=4), 3 patients had plaques with collagen (P=0.007). Although platelets were noted in all patients, platelet clumps and accumulations of atherosclerotic debris were noticeably absent. Atherosclerotic risk factors failed to correlate with luminal surface characteristics. The authors identified specific luminal surface characteristics that correlated well with clinical presentation. Thromboxane inhibitors, such as aspirin, were successful in inhibiting the formation of platelet clumps but were obviously unsuccessful in reducing cellular and matrix accumulations on the luminal surface of carotid arteries.