Critical mechanical conditions around neovessels in carotid atherosclerotic plaque may promote intraplaque hemorrhage

ObjectiveIntraplaque hemorrhage is an increasingly recognized contributor to plaque instability. Neovascularization of plaque is believed to facilitate the entry of inflammatory and red blood cells (RBC). Under physiological conditions, neovessels are subject to mechanical loading from the deformation of atherosclerotic plaque by blood pressure and flow. Local mechanical environments around neovessels and their relevant pathophysiologic significance have not yet been examined.Methods and resultsFour carotid plaque samples removed at endarcterectomy were collected for histopathological examination. Neovessels and other components were manually segmented to build numerical models for mechanical analysis. Each component was assumed to be non-linear isotropic, piecewise homogeneous and incompressible. The results indicated that local maximum principal stress and stretch and their variations during one cardiac cycle were greatest around neovessels. Neovessels surrounded by RBC underwent a much larger stretch during systole than those without RBCs present nearby (median [inter quartile range]; 1.089 [1.056, 1.131] vs. 1.034 [1.020, 1.067]; p < 0.0001) and much larger stress (5.3 kPa [3.4, 8.3] vs. 3.1 kPa [1.6, 5.5]; p < 0.0001) and stretch (0.0282 [0.0190, 0.0427] vs. 0.0087 [0.0045, 0.0185]; p < 0.0001) variations during the cardiac cycle.ConclusionsLocal critical mechanical conditions may lead to the rupture of neovessels resulting in the formation and expansion of intraplaque hemorrhage.

► High mechanical stress and stretch around the neovessles within the carotid atherosclerotic plaque were discovered. ► Neovessels surrounded by red blood cells (presumably evidence of fresh hemorrhage) underwent a much larger stress and stretch than those without red blood cells present nearby. ► These critical mechanical condition may damage the neovessles' wall promoting the formation of intraplaque hemorrhage.