Repolarization of the ventricular myocardium of the heart in young swimmers with functional bradycardia and tachycardia at baseline

The article is focused on the study of the process of excitability restoration of the ventricular myocardium of the heart using multichannel ECG mapping in athletes with different heart rate at baseline. The electrical activity of the heart was studied from 64 unipolar electrodes on the thorax surface synchronously with standard limb leads in young swimmers with moderate bradycardia (n = 15) and tachycardia (n = 10) at rest. The spatiotemporal and amplitude parameters of the electrical field of the heart during ventricular repolarization were measured. ECGII was used to determine the durations of the R–R, QT, T–P, J–Tpeak, Tpeak–Tend, J–Tend intervals; the durations of the corrected intervals were calculated: QT (QTc), J–Tpeak / QT, J–Tend / QT, Tpeak–Tend / QT, QTpeak / QT, J–Tpeak / J–Tend, Tpeak–Tend / J–Tend. The dispersion of the QT interval in each ECG lead (I, II, III, 64 thoracics) was calculated. It was revealed that with statistically significantly different durations of the RR and QT intervals, the durations of J–Tpeak, Tpeak–Tend, J–Tend and corrected intervals in the rersons of the compared groups were almost similar. The spatio-temporal organization of heart ventricular repolarization according to multichannel ECG mapping data in swimmers of both groups was typical for a healthy person. Swimmers with moderate tachycardia show an increase in the dispersion of the QT interval and the positive extreme achieve maximal amplitude earlier, which may indicate an increase in the heterogeneity of the heart ventricular repolarization and an increase in arrhythmogenic risk.