gms | German Medical Science

Objective: The aim of this study was to investigate the correlation between the activities of the carotid vasa vasorum and carotid plaque vulnerability using indocyanine green-video angiography (ICG-VA) during Carotid endarterectomy (CEA), focusing on how the carotid artery vasa vasorum is depicted.

Method: Sixty-nine patients who underwent CEA were enrolled prospectively from September 2013 to December 2014. ICG was injected intravenously as a bolus before and after resecting the atheroma during CEA. We also performed immunohistochemistry using CD68 (macrophage), CD117 (mast cell), CD4 (T-cell), and CD8 (T-cell) antibodies for resected plaque specimens.

Results: Active vasa vasorum density was observed in all patients on ICG-VA (n = 69). The vasa vasorum externa (VVE) and -interna (VVI) were seen in 11 (16%) and 57 patients (82.6%), respectively. The types of VVE were strongly associated with preoperative angiographic instability (90.0%, p = 0.005) and carotid plaque vulnerability (100%, p = 0.007) macroscopically. In contrast, the types of VVI were less associated with angiographic instability (36.1%) and plaque vulnerability (49.1%, p=0.003). CD68- and CD117-stained macrophages and mast cells were observed more frequently in unstable plaque, compared to those in stable plaque (p< 0.0001, p= 0.002, respectively.

Conclusions: The early appearance of VVE on ICG-VA was strongly associated with unstable carotid plaque and many microvessel channels that provided nutrients to the developing and expanding atheroma. Macrophages and mast cells were involved in the formation of microvessels in the unstable plaque phenotype.