Table 4.

Spectral analysis of heart rate and blood pressure variability

	All Controls	All POTS	IOH Controls	IOH POTS	Non-IOH Controls	Non-IOH POTS
n	32	39	24	20	29	19
Total HRV	3,531 ± 458	1,068 ± 148*	2,387 ± 645*	1,047 ± 178*	4,577 ± 652	1,091 ± 153*
LF HRV	976 ± 128	439 ± 88*	940 ± 127	395 ± 104*	921 ± 149	372 ± 72*
HF HRV	1,729 ± 326	401 ± 60*	1,354 ± 455	414 ± 72*	2,594 ± 390	346 ± 70*
Total BPV	9.68 ± 1.17	12.15 ± 1.63	12.15 ± 1.49*	13.39 ± 1.49*	9.11 ± 1.71	10.49 ± 1.49
LF BPV	2.64 ± 0.30	3.44 ± 0.20*	3.66 ± 0.22*	3.92 ± 0.42*	2.08 ± 0.25	2.98 ± 0.39
HF BPV	1.39 ± 0.15	1.18 ± 0.15	1.57 ± 0.12	1.25 ± 0.16	1.39 ± 0.20	1.27 ± 0.20
α-Index	20.1 ± 1.3	11.2 ± 0.7*	15.4 ± 0.9*	11.1 ± 1.1*	20.9 ± 1.6	11.1 ± 0.8*

Data are means ± SE; n = no. of patients. BPV, blood pressure variability; HF, high frequency; HRV, heart rate variability; LF, low frequency; IOH, initial orthostatic hypotension; POTS, postural tachycardia syndrome;

^*P < 0.05 different from all controls.