Figure 2.

ANS (left) and HRV (right) responses from 5 minutes seated to a quick stand followed by 5 minutes of standing during a follow-up test (test N + 1), approximately 3 months postdosing. (Left) Sympathetic (LFa) and parasympathetic (RFa) measures, sympathovagal balance (SB = LFa/RFa), systolic BP, and mean HR. (Right) Normalized low- and high-frequency parameters (LFnu and HFnu, respectively), total spectral power (TSP), and range HR. These data are from patients first presenting with orthostatic symptoms and for whom midodrine was introduced and are reporting significantly fewer orthostatic symptoms, as evidenced by the change from an average decrease in systolic BP during the first test (Figure 1) to an average increase in systolic BP presented in this figure (P < 0.0010). See text for details.