SINUS NODE DYSFUNCTION IN PREMATURE NEWBORNS AFTER PERINATAL HYPOXIA ACCORDING TO THE HOLTER MONITORING DATA
To reveal main signs of the sinus node dysfunction (SND) in premature newborns after perinatal hypoxia according to the Hotel monitoring data (heart rate analysis), 139 newborns were examined. Group I consisted of 54 premature newborns, gestational age: 30 36 weeks, of body mass of no less than 1,300 g (2,145.3±566.41 g). Group II included 43 premature newborns of 31 36 weeks of gestation and body mass of no less than 1,700 g (2,460.8±369.97 g). Group III (control) included 42 mature newborns. The instrumental examination included neurosonoraphy, standard ECG at rest, echocardiography, and ECG Holter monitoring performed at 18 30 days of life. In Group I as compared with Group III, a higher minimal and mean heart rate during sleep and wakefulness and a lower difference between maximal and minimal heart rate (AHR) were revealed. Circadian index was significantly lower in Group I than in Group II. The significant difference was found for mean, maximal, and minimal heart rate during sleep between Group II and Group III, they were significantly higher in Group II. Circadian index in Group III (mature newborns) was significantly higher than in Groups I and II. No diagnostically significant cardiac arrhythmia was observed in any group of children examined. Among the conduction disturbances revealed, pauses mainly due to sinus arrhythmia and second-degree sino-atrial block were of a special interest. The time-domain indices of heart rate variability were significantly lower in Groups I and II, as opposed to Group III. No significant inter-group differences in spectral heart rate variability indices were revealed. Thus, heart rate in premature newborns, as opposed to mature newborns, is characterized by tachycardia, rigidity, and decreased rate dispersion. The maximal duration of the heart rate pauses in mature newborns was 786 ms, in premature newborns without severe perinatal hypoxia, 816 ms. In premature newborns after severe perinatal hypoxia, at the background of pronounced tachycardia during the entire day and night as well as rigid circadian heart rate profile, long heart rate pauses were revealed, in some patients up to asystole; this can be considered SND.