Spectral analysis of heart rate variability signal induced by noninvasive modulation of venous return

Describes a simple device designed to modulate central venous return and to evaluate its effect on the heart rate variability (HRV) signal. The device consists of four cuffs, placed on the arm and leg radices, which are cyclically inflated at 40 mmHg pressure and then deflated. Twenty-eight normal subjects were studied in supine position. The experiment consisted of four periods lasting ten minutes each. The first was a controlled breathing period (CB6=6 breaths/min), the second was CB6 and venous return modulation at 15 cycles/min (VRM15). The third was a controlled breathing period at 15 breaths/min (CB15), and the fourth was CB15 and VRM at 6 cycles/min (VRM6). The heart period respiratory signal, systolic and diastolic blood pressure were monitored during the experiment. Auto- and cross-spectral analysis was carried out on the resulting time series. The results show that Total Power, LF, HF and LF/HF significantly increased only in the CB15 & VRM6 (compared to the CB15) period. In conclusion VRM appears to influence the HRV signal in the low but not in the high frequency.