Cerebral Ischemia and Infarction From Atheroemboli <100 μm in Size

Abstract

Background and Purpose— To determine the importance of emboli not trapped by carotid angioplasty filtration devices, we examined fragments Methods— Human carotid plaques (21) were excised en bloc, and ex vivo carotid angioplasty was performed. Eight plaques were selected as either highly calcified (4) or highly fibrotic (4) by high-resolution MRI (200 μm ³ ). Fragments were counted by a Coulter counter. Before injection into male Sprague-Dawley rats, fragments from calcified and fibrotic plaques were sized with 60-, 100-, and 200-μm filters. Brain ischemia and infarction were assessed by MRI scans (7-T small-bore magnet) and by immunohistologic staining for HSP70 and NueN. Results— All 5 animals injected with 100- to 200-μm calcified fragments had infarctions. One was lethal. After injection of 60- to 100-μm calcified fragments, 7 of 12 animals had cerebral infarctions, whereas only 1 of 11 had infarctions with fibrous fragments ( P Conclusions— Hundreds of thousands of microemboli can be shed during carotid angioplasty. Fragments from calcified plaques cause greater levels of infarction than fragments from fibrous plaques, although ischemia is common with both fragment types.