The cardiovascular system involves many regulatory mechanisms that maintain the stability of blood pressure by interacting strongly with other vital systems (including the respiratory, endocrine, and autonomous nervous systems). Non-invasive measurements of cardiovascular signals have enhanced the study of the cardiovascular system, providing deeper insights into its physiological modulation, the pathophysiology of cardiovascular and other chronic diseases, and new methods to improve their diagnosis and prognosis. Heart rate variability (HRV) and other time series derived from the cardiovascular system can be considered as outputs of this system, whose changes in response to a given stimulus can provide information about regulatory mechanisms.

This Special Issue presents interesting advances in the analysis of HRV in both healthy individuals and patients with various pathologies. It collates studies on the assessment of the nonlinear properties of HRV signals, as well as the nonlinear interactions between heart rate and respiration, revealing an interesting interplay between the cardiovascular and respiratory systems.