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CONNECTION BETWEEN THE PARAMETERS OF ECG SUPRAVENTRICULAR COMPONENT AND BRONCHIAL HYPERREACTIVITY IN CHILDREN WITH BRONCHIAL ASTHMA

Uncontrolled course of bronchial asthma (BA) is associated with the risk of heart rhythm disturbances. Objective of the study: to analyze the electrocardiographic parameters of the atrial complex and atrioventricular conduction and to assess their relationship with changes in spirometric parameters in tests with dosed physical activity (PA), reflecting bronchial hyperreactivity (BHR) in children with BA. Materials and methods of research: assessment of the parameters of the supraventricular component of the ECG in comparison with changes in spirometric parameters in tests with dosed PA was performed in 55 children aged 6–17 years with atopic asthma. To level the effect of age on ECG indices, the «relative PQ» (rPQ) index was introduced, calculated as the ratio of the patient's PQ interval duration to the median PQ values characteristic of a given age and gender. Results: it was found that a decrease in the Tiffno index (TI) in tests with PA is accompanied by a statistically significant increase in the rPQ index, an increase in the PQ segment (sPQ) and an increase in the proportion of the PQ interval in the structure of the R–R interval (PQ/RR); similar patterns were obtained when comparing the variability instantaneous volumetric expiratory flow rate at the level of 25% of the vital capacity of the lungs (MOS25). Analysis of the available data indicates a statistically significant lengthening of the PQ and sPQ intervals, as well as an increase in the rPQ and PQ/R–R indices in children with BA as the afterload changes in the small bronchi, indirectly assessed by MOC25. Conclusion: children with asthma who have spirometric signs of BHR in the test with PA may have electrocardiographic signs of a slowdown in supraventricular conduction.