Cardiovascular response to sinusoidal neck suction in healthy volunteers and orthostatic intolerance patients

The dynamic response to sinusoidal neck suction, of the RR interval, systolic arterial blood pressure and muscle sympathetic nerve activity series, was studied in 10 controls and 5 patients with orthostatic intolerance. By using different spectral techniques (autoregressive, short time Fourier transformation), the cardiovascular and MSNA variability were analyzed during 0.1 Hz and 0.2 Hz frequency of neck suction. Moreover, by using the autoregressive model, a quantitative analysis of particular power spectral frequency bands was done. Finally, a chirp neck suction input signal was applied to qualitatively compare the frequency response. The patients with orthostatic intolerance showed a partial blood pressure response to NS, particularly over 0.1 Hz compared to controls.