Abstract 14763: Vascularization Is Increased In Up-stream Regions Of Carotid Endarterectomies
Vascularization of plaque tissue is suggested to contribute to plaque vulnerability via intra-plaque hemorrhage (IPH). We have shown that up-stream (US) sections of carotid endarterectomies have more vulnerable histological phenotype compared with down-stream (DS) sections possibly caused by exposure to high shear stress in contrast to turbulent flow patterns. We assessed the hypothesis that US regions of atherosclerotic plaques have an increased vascularization compared to DS regions and that this increased vascularization is associated with IPH. Methods: US and DS sections were identified in carotid endarterectomies from symptomatic patients (n=46) using pre-operative magnetic resonance angiography imaging. Paired cross-sections (n=46 pairs) were taken for histological examination and immunohistochemistry. CD34+ vessels were counted in the full sections and the percentage of CD68+ area was used as an index of macrophage density. Lipid rich necrotic core were excluded. Results: US sections were taken at a median of −4.1 mm from the point of maximum stenosis and DS sections at +3.9 mm. The CD34+ vessel density was higher (p=0.005) in the sections prepared from the area US of the maximum stenosis (median 4.45 (IQR 9.85) n/mm2 vs. 1.47 (IQR 5.86) n/mm2). CD68+ macrophages were also more abundant in US sections (p=0.007). There was a significant and positive correlation between CD34+ vessels and CD68+ macrophages in both US and DS sections (p≤0.005). US sections with IPH had higher CD34+ vessel density (p = 0.029) and more macrophage staining (p = 0.010) compared with sections without IPH. We conclude that there is an intra-plaque gradient in vascularization with a denser vascular network in the regions of the plaque exposed to high shear stress compared to the regions exposed to turbulent blood flow. IPH is associated with high vascular density and supports the hypothesis that vascularization is linked to plaque vulnerability.
- © 2011 by American Heart Association, Inc.