PECULIARITIES OF HEART RHYTHM IN PREMATURELY BORN CHILDREN WITH BRONCHOPULMONARY DYSPLASIA

Heart rate variability is the most accessible method of estimating the body’s sympatho- parasympathetic balance and is based on the study of spontaneous heart rate fl uctuations. The method of heart rate variability is not specifi c for certain nosologies, but it is highly sensitive for assessing the degree of functional disorders, predicting the course of the disease and evaluating the eff ectiveness of therapy. The purpose of the study was to study the features of the heart rhythm in prematurely born children who suff ered respiratory distress syndrome and developed bronchopulmonary dysplasia.Materials and methods. Observations of 41 preterm infants with gestational age from 27+1 to 34+6 weeks with respiratory distress syndrome of 2nd to 3rd degree requiring respiratory support were analyzed. The fi rst group consisted of 18 preterm infants who developed respiratory distress syndrome, required respiratory support and developed bronchopulmonary dysplasia; the II group – 23 preterm infants who developed respiratory distress syndrome, required respiratory support but did not develop bronchopulmonary dysplasia. In order to assess the characteristics of the heart rhythm and its variability, a resting ECG and daily ECG monitoring were performed at the age of 10-14 days. Statistical analysis was performed with the standard package of Statistica software (StatSoft Inc., USA, version 10).Nonparametric Pearson and Fisher tests were used to determine the reliability of diff erences between indicators. A signifi cance level of p<0.05 was considered reliable. The study was conducted within the framework of scientifi c research work of the Department of Pediatrics № 3 and Neonatology of Kharkiv National Medical University «Study of peculiarities of the course of oxidative stress diseases in newborns» 2022-2024 (state registration # A22U000025). According to the decision of the Bioethics Commission № 3 dated March 21, 2023, the study materials comply with the Tokyo Declaration of the World Medical Association, the international recommendations of the Helsinki Declaration of Human Rights, the Convention of the Council of Europe on Human Rights and Biomedicine, the laws of Ukraine and the requirements of the Code of Ethics of a Doctor of Ukraine.Results and discussion. The studied groups were representative with regard to gestational age, birth weight and sex. Children inthe fi rst group had signifi cantly lower Apgar scores: at 1 minute 3.08±0.27 versus 4.12±0.24 (p<0.001), at 5 minutes 4.48±0.26 versus 5.91±0.25 points (p<0.001). Respiratory support was provided to all children in the study. The mean duration of respiratory support, frequency of use of high-frequency oscillatory ventilation, frequency of diagnosis of pulmonary hypertension were signifi cantly higher in children of the 1st group: 21.6±2.6 versus 12.3±3.1 days (p<0.001), 44.4 % versus 8.7 % (p<0.001) and 38.9 % versus 4.4 % (p<0.001), respectively. This refl ects the greater severity of damage to the child’s respiratory system. Of course, the mean hospital stay of children in the 1st group was signifi cantly longer, 41.3±3.0 versus 32.6±3.8 days (p<0.001). The groups did not diff er in the frequency of intraventricular hemorrhage stage II-III, periventricular leukomalacia stage II-III, anemia of prematurity, hearing impairment.Hemodynamically signifi cant patent ductus arteriosus and retinopathy of prematurity stage II-III were observed signifi cantly more often in children of the fi rst group, 5 (22.2 %) versus 1 (4.4 %) (p<0.01) and 8 (44.4 %) versus 5 (21.7 %) (p<0.05), respectively. The most common arrhythmias observed during the study were sinus tachycardia and supraventricular extrasystole. In the children of the 1st group, sinus tachycardia was observed signifi cantly more often 94.4 % versus 73.9 % (p<0.01) and, accordingly, the mean heart rate in the 1st group was more than 160.2±12.6 bpm versus 146.6±14.4 bpm (p<0.01). In the children of the 2nd group supraventricular extrasystoles were observed signifi cantly more often (95.7 % vs. 72.2 % (p<0.01) and migration of the pacemaker through the atria 17.4 % vs. 0 % (p<0.001).When evaluating heart rate variability in both groups of children during sleep and wakefulness, a decrease in TR and HF indicators below the 3rd percentile of the normative tables for the corresponding age was observed, and an increase in LF/HF indicator above the 97th percentile is natural, which indicates a signifi cant excess of the infl uence of the sympathetic nervous system in prematurely born children who went through respiratory distress syndrome II-III stage and required respiratory support. When comparing the two groups, no signifi cant diff erences were found in heart rate variability indicators while awake. During sleep, the infl uence of the parasympathetic link of the nervous system was increased in the children of the II group compared to the awake state, and in the children of the I group, parasympathetic modulation of heart rate variability during sleep was not observed.Conclusions: Daily monitoring of ECG allows to reveal peculiarities of vegetative state of children with perinatal pathology.Sinus tachycardia and supraventricular extrasystole are the most common cardiac dysrhythmias. In premature infants, who underwent respiratory distress syndrome II-III stage and required respiratory support, a characteristic vegetative imbalance with a signifi cant excess of the infl uence of the sympathetic link of the central nervous system, which is clinically manifested by sinus tachycardia. The absence of parasympathetic modulation of heart rate variability during sleep in prematurely born children who developed bronchopulmonary dysplasia (children of the 1st group), in contrast to children of the 2nd group who did not develop bronchopulmonary dysplasia, indicates a more signifi cant violation of the function of the central nervous system due to an increase in the infl uence of the sympathetic link and correlates with the formation of chronic lung pathology.