Comparative investigation of mechanical characteristics of stable and unstable carotid atherosclerotic plaques

Abstract

The prognosis of patients with carotid atherosclerosis is determined by the factor of unstable atherosclerotic plaque. Change of longitudinal strain in junction place of healthy artery wall to plaque determined by local artery elasticity and leads to instability. Aim of the study: Comparative investigation of mechanical characteristics of the stable and unstable plaques in a carotid artery. Methods: In the main group (MGr) were studied 16 plaques with stenosis 7090%, and control group (CGr) 33 plaques with stenosis 25-45%. Carotid ultrasound examinations (PHILIPS iU22) were performed for estimated structure and stenosis of plaques. The ”healthy” wall stiffness (free from plaques -bhw) and plaques zone stiffness (in adventitia -badv and in plaques surface -bpl) were estimated using echo-tracking method by ALOKAa7 in B/M mode ultrasound imaging. Results: In the MGr majority of plaques had structure with hypoechogenic area (>50%) and calcification, third plaques had rough or ulcerated surface. In CGr dominated heterogeneous plaques with smooth surface. In both groups bhw was significantly lower, than badv (MGr: 8,95 3,14 vs 22,73 10,43, CGr: 9,43 2,64 vs 14,45 6,7, p<0,001), badv was significantly higher than bpl (MGr: 22,73 10,43 vs 7,7 5,04; CGr: 14,45 6,7 vs 11,69 6,84, p<0,001). Relative changes of plaques zone stiffness (100bpl 100/badv) was significantly higher in the MGr (51,28 24,17% vs 26,93 21,45%, pZ0,036). Conclusions: Our results confirm presence the significant gradient of stiffness in junction place of healthy artery wall to plaque. In group with unstable plaques this gradient was significantly higher, that allows considering the possibility of the unstable plaques criteria developing by echotracking method.