[Chronobiological pattern size of cardiac rhythm (author's transl)]

The basic knowledge of statistical methods in chronobiology are exposed, for the analysis of chronobiological features of cardiac rhythm. The cosinor's method, with definition of chronobiological parameters (acrophase, mesor and amplitude) allows a microscopic approach to study of biological rhythms. The AA. relate some chronobiological studies: a) on heart rate in normal subjects and in patients with myocardial infarction (MI); b) on premature ventricular beats in MI; c) on atrial and ventricular rates in complete AV block. These results demonstrate that there is an evident circadian rhythmicity for all analyzed parameters. The AA. analyse the physiological and clinical meaning of the chronobiological approach to cardiac rhythm for the chronopharmacological and pathophysiological studies and suggests the implications in pathology of adaptation to shift work.