. An exact description of circadian and ultradian rhythms of simple extrasystoles in healthy subjects is lacking. Thirty-seven healthy male subjects, aged 50–76, were randomly taken. Simple extrasystoles from 24-hour Holter ECG were registered and calculated per each hour and processed by cosinor regression. Their occurrence is formulated by 95% confidence and tolerance corridors for supraventricular and ventricular extrasystoles.
. The number of extrasystoles is relatively low, dispersion of ventricular extrasystoles is significantly higher than supraventricular ones. A significant increase of their frequency versus the general zero trend straight line was found only around 9 a.m. In supraventricular ones a significant increase around 6–7 a.m., 9 a.m., noon, and 4–5 p.m. and a significant depression around 1–2 a.m. and 10 p.m. was present. Only the 24-hour rhythm is significantly present (α=0.05) in ventricular beats while in supraventricular ones also the period lengths of 12, 6, 4, 3.4 and 2.4 hours are significant. The significant difference between supraventricular and ventricular extrasystoles exists in the 24-hour amplitudes and 6-hour acrophases.
. One circadian and several ultradian rhythms of simple extrasystoles are present in healthy male subjects over 50 years of age. The 95% tolerance chronograms can be exploited in clinical practice.