Morphological Changes in Inspiratory Muscles in Chronic Heart Failure

The aim was to study the structural and functional reorganization of the sternocleidomastoid muscle, diaphragm and external intercostal muscles in chronic heart failure (CHF). Material and methods . Three groups of inspiratory muscles were studied: sternocleidomastoid muscle, diaphragm, external intercostal muscles, as well as psoas minor muscle as a control in 24 dissected male cadavers. Based on the presence of CHF and its stage, patients were divided into three groups: without signs of CHF (n=8), with CHF stage I-IIA (n=8), with CHF stage IIB-III (n=8). Histological sections were stained with histological and immunohistochemical techniques (CD34 biomarker expression was detected to determine the activity of angiogenesis and capillary density). Neutral polysaccharides (glycogen) were determined by the PAS reaction. The morphometric study was used to calculate the relative area of endomysial vessels and the diameter of muscle fibers. Results . In patients without signs of CHF, among all the muscles studied, the most pronounced changes were observed in the diaphragm. The highest indicators of the relative area of blood vessels and capillary density on a conditional unit of area were revealed; thickened myosimplasts prevailed and the most intense PAS reaction was revealed. As heart failure increases, the number of capillaries in the diaphragm decreases, glycogen reserves are depleted and the number of thin myosimplasts increases. In external intercostal muscles, the maximum values of relative vascular area and capillary density were observed in CHF stage I-IIA. In all groups, medium-thick myosiplasts prevailed in this muscle. In sternocleidomastoid muscle, the highest indicators of relative vascular area and capillary density were found in the group with CHF stage I-IIA. In CHF stage IIB-III, these indicators did not decrease compared to the group without CHF. The psoas minor muscle study revealed an increase in the relative vascular area in CHF stage IIB-III compared with the group without CHF, which is probably due to venous congestion. Conclusion . The revealed structural and functional reorganization of inspiratory muscles depends on the degree of their participation in the breathing. Each muscle reacts differently to the increase in heart failure with the appearance of signs of compensation and decompensation, depending on the stage of CHF.