Reconstructing cardiovascular dynamics

The signals that originate from the human cardiovascular system were analys ed using methods of both linear and nonlinear system theory. The analyses i n the time domain and in the phase space revealed the deterministic and alm ost conservative nature of the cardiovascular control system on the time sc ale of minutes. Five characteristic frequencies were found in the signal of peripheral blood flow. Some of them had already been found in other cardio vascular functions, the breathing, blood pressure, ECG and HRV. Each charac teristic peak reflects the periodic action of one of the subsystems, involv ed in the regulation of the blood Row. These systems are mutually dependent , via the couplings among them. Their strength plays an essential role in t he performance of the system. In some cases their importance is indicated, thus pointing to practical applications in the diagnosis and prediction of cardiovascular functions. (C) 1999 Elsevier Science Ltd. All rights reserve d.