Adaptive capacity of the cardiovascular system in children with rheumatic diseases and comorbid conditions

Abstract

Purpose: to study the functional state of the cardiovascular system and its adaptive reactions in children with rheumatic diseases, taking into account the development of comorbid conditions. Materials and methods. 44 patients with RD were examined, 8 of them with systemic lupus erythematosus, 36 with juvenile idiopathic arthritis. The average age of the children was 13.39 ± 0.82 years. To study tolerance to the minimum physical activity and its influence on the state of the CVS in children, a six-minute walk test (SMWT) was conducted. To assess the functional intensity of the CVS, the following indices were calculated before and after the SMWT: Allgower index, endurance coefficient according to Kvas formula, Robinson index, coefficient of circulatory efficiency. To assess the influence of the vegetative nervous system (VNS) on the CVS activity, Kerdo vegetative index (KVI) was determined. At rest, the functional changes index (FCI) of the circulatory system, or the adaptation potential (AP), was also determined. Results. In patients with RD, there is a reduced tolerance to minimal physical activity with an increase in the functional tension of the cardiovascular system and activation of the sympathetic division of the autonomic nervous system. When analyzing the functional stress of the cardiovascular system in children with RD and the presence of comorbid pathology, significantly higher values of the adaptation potential and Allgower index were revealed, which indicates the formation of disturbances in the circulatory system against the background of the breakdown of the adaptation mechanisms of the cardiovascular system. The KVI indicates activation of the sympathetic part of the autonomic nervous system in them and an increase in the catabolism processes characteristic for intense functioning with the expenditure of the body's energy reserves. When evaluating these indicators in children without comorbid conditions, the negative KVI value indicates activation of the parasympathetic division of the VNS, which indicates a more favorable, anabolic variant of the shift and more economical mode of functioning of the body systems. Conclusions. Children with RD showed a decrease in tolerance to the minimum physical load in the SMWT, as evidenced by the percentage increase in heart rate and the distance traveled. Tension in the cardiovascular system’s work and a decrease in its functional capabilities were also revealed, as evidenced by a significant increase in the Robinson index, Allgower index and the endurance coefficient both before and after the SMWT. In children with RD and the presence of comorbid pathology, higher values of adaptation potential, Allgover index and Kerdo vegetative index were established, which indicates the formation of disturbances in the circulatory system against the background of the breakdown of its adaptive capabilities.