Short- and long-term statistical properties of hertbeat time-series in healthy and pathological subjects

We analize heartbeat time-series corresponding to several groups of individuals (healthy, heart transplanted, with congestive heart failure (CHF), after myocardial infarction (MI), hypertensive), looking for short- and long-time statistical behaviors. In particular we study the persistency patterns of interbeat times and interbeat-time variations. Long-range correlations are revealed using an information-based technique which makes a wise use of the available statistics. The presence of strong long-range time correlations seems to be a general feature for all subjects, with the exception of some CHF individuals. We also show that short-time properties detected in healthy subjects, and seen also in hypertensive and MI patients, and completely absent in the transplanted, are characterized by a general behavior when we apply a proper coarse- graining procedure for time series analysis.