Ultrastructural characteristics of erythrocytes and their relationship with oxygen transport in patients with ischemic heart disease after coronary artery bypass grafting with artificial circulation

Abstract

Aim. Evaluation of nanostructural and micromechanical characteristics of erythrocytes and their relationship with the parameters of oxygen transport in patients with ischemic heart disease (IHD) after coronary artery bypass grafting (CABG) under artificial circulation (AC).Materials and methods. The study involved 30 men with IHD aged 53 to 67 years with a median of 63 years, who underwent planned CABG with AC at the clinic of the Far Eastern Federal University. Blood sampling from patients was carried out before the AC and one day after it from a venous catheter located in the right atrium. Erythrocytes were scanned using a Bioscope Catalyst atomic force microscope (AFM) (Bruker, USA) in combination with an Axiovert 200 inverted microscope (Zeiss, Germany). The micromechanical properties of cell membranes were investigated with the PFQNM-LC-A-CAL cantilevers. The following were recorded: the diameter of erythrocytes, the height of their side, area, volume, membrane rigidity, strength of its adhesion, Young's modulus, elastic deformation. To assess oxygen transport, the oxygen delivery index (DO2I), consumption (VO2I), and extraction ratio (O2ER) were calculated.Results. In one day after CABG, a decrease in DO2I, VO2I, and O2ER was recorded by 14%, 33%, and 16%, respectively, which indicated a limitation in the gas transport function of the blood. Analysis of the AFM characteristics of erythrocytes showed an increase in their area by 35%, in diameter by 6%, in volume by 19%, and the height of the side by 5 times. At the same time, multidirectional changes in the micromechanical properties of erythrocyte membranes were noted: Young's modulus and stiffness decreased by 3.2 and 2 times, respectively; the adhesion force increased by 2.7 times, and the elastic deformation – by 2.2 times. Correlation analysis showed the presence of reliable relationships between indicators of oxygen transport and biomechanical parameters of erythrocyte membranes.Conclusion. A comprehensive analysis of the nanostructural parameters of erythrocytes and oxygen transport expands the understanding of the pathophysiological mechanisms of postperfusion disorders in patients with coronary artery disease after CABG under conditions of cardiopulmonary bypass.