Hemodynamic regulation during postural tilt assessed by heart rate- and blood-pressure variability combined with impedance cardiography.

Assessment of heart rate and heart rate variability (HRV) are used in sports medicine and space medicine to give conclusions about the functional state of the autonomic nervous system. Furthermore, reduced HRV and changed blood pressure variability (BPV) are accepted as risk factors in patients with cardiovascular diseases, metabolic syndrome and neurologic disorders. The aim of the first studies was to combine the evaluation of central hemodynamic (impedance cardiography) with HRV and BPV evaluation in the time and frequency domain (fft tracking) based on a standardized clinical test with automated protocol output. Data acquisition and -analysis was realized beat to beat (Kohto Ltd., Moscow) during forced breathing (150 s, 6 breath/min) and postural tilt (7 min, supine, transition to 55 degrees in 4 s, 7 min upright) allowing one to evaluate: orthostatic response type including impedance cardiography; activation of vagal afferences and efferences by forced breathing; vagal and sympathetic components during initial heart rate and blood pressure responses; characteristic changes of spectral balance of HRV and BPV (measured at the finger) during early regulation. First investigations on 34 normal volunteers subdivided into two age groups and on 13 patients with different diseases indicate that besides the age dependent changes (reduced HRV, reduced cardiac performance, reduced regulatory amplitudes and baroreflex sensitivity) individual response types can be described and dysfunction of different reflex loops can be detected. Consequently, the assessment of specific influences onto circulatory control by therapy, sport and rehabilitative training is possible and further studies are necessary.