[Cardiac rhythm in sleeping healthy adolescents as recorded by holter ECG monitoring].

AIM

To characterise cardiac rhythm dynamics in sleeping adolescents by heart rate trend in Holter monitoring (HM).

MATERIALS AND METHODS

Synchroneous HM and classical night EEG-polygraphy from 22.00 to 08.00 were conducted in 9 healthy adolescents (5 boys and 4 girls) aged 10-15 years. The heart rate trends in sleep exhibited periods of stable rhythm (PSR) and periods of enhanced dispertion (PED) which took 38.4 and 61.6% of the sleep duration, respectively. PED occurred 5.3 +/- 0.16 times per night. The comparison of the heart rate trends to night sleep structure reflected at EEG indicated that fast sleep coincided with PED in 100% of cases being in the middle of PED cycle. PED incorporated also fragments I and II of slow wave sleep (SWS). PSR were represented primarily with phases II and IV of SWS. Step-by-step scanning of the right space of the interval histograms showed that maximal slowering of cardiac rhythm occurred in SWS phase II and fast sleep (76.5 and 23.5%, respectively).

CONCLUSION

The profile of the heart rate night trend in HM reflects an independent ultradian rhythm. Maximal cardiac rhythm unstability and bradycardia occurred, respectively, in fast sleep and phase II of SWS.