Evaluation of Carotid Artery Embolic Debris by Electron Microscopy and Energy Dispersive Spectroscopy

Abstract

Objectives Little is known regarding the compositional characteristics of embolic debris produced during carotid artery stenting (CAS). We examined this debris using electron microscopy (EM) and energy dispersive spectroscopy (EDS) in symptomatic and asymptomatic patients. Methods CAS for high-grade stenosis was performed in 163 patients between 2003 and 2005. Presence of calcification and degree of stenosis was determined angiographically. Microporous embolic protection filters were used in 160, and 11 protection devices (5 symptomatic, 6 asymptomatic patients) were processed for scanning and transmission EM to assess morphology and cellular composition of debris. Calcium content within captured debris was quantified by EDS. Results Captured debris varied between patients and ranged from red blood cells without other components, to clumps of recently activated platlets with early fibrin cross-linking, to coalescing areas of well-organized platlet thrombus. Advanced platlet activation was more common in symptomatic than asymptomatic patients (100% vs. 33%, respectively, p<0.05). Despite the presence of known calcified lesions in 54% of patients, no calcium was detected in the debris by EDS. Conclusions Debris captured during CAS with embolic protection exhibits a range of cellular and acellular components on EM, with increased amounts of platlet activation evident in symptomatic patients. Calcium was not detected in the emboli, even in patients with calcified lesions on angiography.