Localization habits and composition of mineral deposits in atherosclerotic plaques of coronary arteries according to the scanning electron microscopy and X-ray diffractometry

Abstract

Target. A detailed study of the morphology, localization and composition of calcifications of atherosclerotic plaques of the coronary arteries of the heart to identify the connection between the calcification process and some key stages of atherosclerotic lesions. Materials and methods. Samples for research - atherosclerotic plaques obtained from five patients during coronary artery bypass grafting. Micromorphology and localization of mineral deposits have been studied by scanning electron microscopy. The elemental and phase composition of the calcifications was identified by energy dispersive and X-ray diffraction analysis. Results. Calcification of the coronary arteries is associated with three stages (types) of atherosclerotic lesions. Massive calcifications of fibrous areas have a layered or platy structure, and include a relatively large amount of residual organic matter. Mineral deposits in mature atheromatous foci are fused with a minimum amount of organic carbon. Areas of hemorrhage and thrombus formation are also subject to petrification with the formation of loose deposits with a high content of organic matter. The formation of accumulations of micro- and nanosized particles of hydroxyapatite is the initial phase of the development of extensive calcifications in atherosclerotic plaques. The peculiarities of the size distribution of calcium-containing particles indicate differences in the mechanisms of their formation within plaques and in the area of ​​contact with blood. In the first case, the mechanism of active synthesis of hydroxyapatite with the participation of membrane vesicles is indirectly confirmed; in the second, the formation of mineral nanoparticles is most likely the result of the crystallization process from solution. Conclusion. Continuation of research using the methods used in this work will allow to establish a quantitative relationship between the types or stages of atherosclerotic lesions of the coronary arteries and the severity of the petrification process.