THE EXPONENTIAL-DISTRIBUTION APPLIED TO NONEQUIDISTANTLY SAMPLED CARDIOVASCULAR TIME-SERIES

Beat-to-beat fluctuations in cardiovascular time series comprise diffe rent frequency components which can be employed to describe autonomic regulatory processes. The Exponential Distribution (ED) is presented h ere as a specific time-frequency distribution which has the potential to describe the time-related changes in the frequency content of these cardiovascular fluctuations. The ED has as advantage that it gives a good suppression of the cross terms, a characteristic feature of bilin ear time-frequency distributions. An implementation to apply the ED to nonequidistantly sampled cardiovascular time series is provided. Appl ications of the ED to various clinical and experimental human cardiova scular time series show that the ED can be an important aid to describ e and interpret time-varying frequency components of cardiovascular si gnals such as heart rate, interbeat interval, blood pressure, and resp iration. (C) 1996 Academic Press, Inc.