Abstract 3404: Increased Spatial Vasa Vasorum Density in the Proximal LAD in Hypercholesterolemia -Implications for Vulnerable Plaque-Development
Objective: Vasa vasorum (VV) neovascularization is associated with advanced and ruptured atherosclerotic lesions that occur predominantly within the proximal third of the LAD. Thus, we investigated the changes in spatial distribution of VV densities along the LAD in the hypercholesterolemic pig model for early atherosclerosis.
Methods and Results: Female domestic pigs were placed on normal (N; n=6) or high-cholesterol (HC; n=6) diet for 3 months. VV count, vascular-volume-fraction, and the endothelial-surface-fraction were calculated from microcomputed-tomography images. In N animals, the proximal thirds tended to have higher vascular-volume-fractions (0.014±0.006 vs. 0.009±0.003 and 0.009±0.002; NS) and endothelial-surface-fractions (0.72±0.29 vs. 0.59±0.22 and 0.53±0.20; NS) than the mid and distal thirds with significantly higher VV counts (26±12, 15±8, 8±5, P=0.01). In HC animals, we observed significant VV neovascularization (#/mm2, 3.3±1.2 vs. 6.8±1.9, P<0.01), with significantly higher VV counts (24±3 and 14±3 vs. 6±4; P<0.001) as well as higher vascular-volume- (0.014±0.002 and 0.014±0.002 vs. 0.008±0.002; P<0.001) and endothelial-surface-fractions (0.88±0.14 and 0.90±0.12 vs. 0.56±0.14; P=0.001) within the proximal and middle thirds compared to the distal thirds. Intima-Media ratios determined in Elastic van Gieson stained histology slides did not differ significantly between the two groups (N vs. HC mean±SD: 0.25±0.11 vs. 0.28±0.12; n.s.).
Conclusions: VV neovascularization in early atherosclerosis shows a proximally accentuated increase in flow-capacity and endothelial-exchange-surface, which may serve as a conduit for the predominant development of vulnerable atherosclerotic plaques in proximal portions of the LAD.