Causes of brain injury during endovascular carotid intervention are protean. Mechanisms of injury include embolic and hemodynamic events, acute carotid occlusions occurring through a variety of means, and the relatively rare contrast-induced encephalopathy.
Embolic injury may result from micro- and macroembolization and most commonly causes ischemic stroke when sufficiently severe. Hemodynamic injury may proceed from hemodynamic depression and hypoperfusion (which may result in watershed infarction) or the hyperperfusion syndrome, which may, if severe, result in hemorrhagic stroke.
Embolic and dynamic causes of stroke may either occur intraprocedurally or at a variable time after stent placement and may be co-related. Impaired clearance of emboli due to relative hypoperfusion may exacerbate their clinical relevance. Other causes of stroke include acute carotid occlusions, which most commonly occur procedurally due to flow-limiting spasm, acute dissection, and, if a filter-type cerebral protection device has been used, filter occlusion due to a large trapped embolic load. These scenarios may result in stroke if not recognized and dealt with appropriately. Acute stent thrombosis may occur within 24 hours of the procedure as a result of adverse hemodynamic factors or suboptimal patient response to procedural heparin and antiplatelet agents, or it may occur after the procedure, again perhaps as a result of suboptimal response to antiaggregate drugs.
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