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Spectral analysis of a female patient (62 years of age) without orthostatic hypotension (the same of Figure 3) in orthostatic position, showing an increase in low frequency (LF) component and in the LF/high frequency (HF) ratio, in relation to supine position. VLF: very low frequency; RR: number of QRS in sinus rhythm; VLF: very low frequency; HFnu: HF normalized unit.
