Analysis of circadian dynamics and heart rate trend during Holter monitoring in children with type 1 diabetes mellitus
Authors:   The O.O. Bogomolets National Medical University, Kryvonos Y.M. 
Published: March 2021

Aim. To determine the diagnostic value of the analysis of circadian dynamics and heart rate trend during Holter monitoring in children with type 1 diabetes mellitus. Material and Methods. Holter electrocardiogram monitoring was performed in 53 children with type 1 diabetes mellitus (DM) (17 boys and 36 girls) who were in the endocrinology department of the Children's Clinical Hospital №6 of the Shevchenkivskyi district of Kyiv. The patients were divided into two groups depending on the duration of diabetes. The first group included 28 children aged 9-17 years with duration of diabetes ranging from 9 months to 5 years. The second group included 25 children aged 12-17 years, with history of diabetes varying from 5 to 15 years. All children received basal bolus insulin therapy, which was documented (time, dose, and name of insulin administered) in their Holter monitoring diaries, as well as the blood glucose levels. Holter monitoring system DiaCard-2 with recorder 03100 (JSC "Solvaig", Kyiv) was used for ECG monitoring. In addition to the standard parameters of daily recording, the circadian dynamics of heart rate (HR), and circadian index (CI) were evaluated; the trend of heart rate was analyzed in relation to the patients' activity, glycemic level, and insulin administration. Results and Discussion. In children with disease duration of 5-15 years (2nd group), the average day time heart rate exceeded both the rates in children with disease duration of up to 5 years (1st group) and normal ranges; a positive correlation was revealed (r=0.53 at p<0.05) between diabetes duration and the average night heart rate in children. In addition, the progressive decrease in CI with the duration of the disease (1.33±0.16 in group 1 against 1.28±0.14 in group 2) indicated a progressive increase of the sympathetic and weakening of the parasympathetic influence on the heart rhythm. Signs of paroxysmal heart rate readiness, presented as increased duration (more than 50% of night sleep time) and/or number of periods of increased heart rate dispersion (more than 5) in combination with hyperreactivity of heart rate on waking, were found in 11 children (20.7%). Correlations between supraventricular tachycardia paroxysms (STP) and reactivity of the cardiovascular system during awakening (r=0.35 at p<0.05), and STP and the percentage of periods of increased heart rate dispersion on the heart rate trend during night sleep (r=0.33 at p<0.05) were revealed. These data may be useful for the early detection of patients with active heterotopic arrhythmias (eg, paroxysms of supraventricular tachycardia), which may not always be detected during Holter monitoring. During analyzing the heart rate dynamics according to the trend and comparing it with the patients' activity, insulin therapy and glycemic levels, an increase in heart rate of 15-25% in average was detected in 38 children (71.6%) 20-30 minutes after injections of short-acting insulin, which corresponds to the onset of their effect, and, after 60-120 minutes - to its maximum. Conclusions. Comprehensive analysis of the results of daily ECG monitoring with analysis of the heart rate trend revealed the effect of basic bolus insulin therapy on heart rate at the onset and maximum of short and ultrashort insulin drugs in 71.6% of patients with type 1 diabetes. Detection of signs of paroxysmal readiness on the heart rate trend may be useful for early detection of patients with active heterotopic arrhythmias that are not always detected during monitoring. Analysis of circadian dynamics of heart rate and circadian index allows to determine the condition of cardiac activity autonomic regulation even in the absence of technical feasibility of analyzing heart rate variability, and is available when using Holter systems of any level. Key words: type 1 diabetes mellitus, Holter monitoring, heart rate trend, circadian index, circadian heart rate dynamics