Table 3.
Indices of cardiac and vascular autonomic profile of POTS patients (n = 19) while supine and during 75° head-up tilt (HUT).
| Parameter | SUPINE | HUT |
|---|---|---|
| RR (ms) | 806 ± 30 | 611 ± 20 * |
| HR (beats/min) | 75 ± 3 | 107 ± 3 * |
| RRvar (ms2) | 2582 ± 746 | 803 ± 139 * |
| LFRR (ms2) | 810.0 ± 227.7 | 337.4 ± 88.9 * |
| LFRR (n.u.) | 61.1 ± 5.5 | 78.2 ± 3.1 * |
| HFRR (ms2) | 961.8 ± 424.7 | 64.3 ± 22.0 * |
| HFRR (n.u.) | 36.2 ± 5.5 | 15.2 ± 2.9 * |
| LF/HF | 3.5 ± 0.8 | 11.7 ± 2.8 * |
| SAP (mmHg) | 108 ± 3 | 110 ± 3 |
| DAP (mmHg) | 66 ± 2 | 71 ± 2 * |
| LFSAP (mmHg2) | 3.2 ± 0.7 | 12.0 ± 2.6 * |
| RESP (cycles/min) | 17.3 ± 0.5 | 16.9 ± 0.7 |
| αLF (ms/mmHg) | 21.3 ± 4.1 | 5.7 ± 0.9 * |
| NE (ng/L) | 252.1 ± 32.3 | 522.0 ± 71.4 * |
| E (ng/L) | 27.4 ± 3.7 | 51.3 ± 7.6 * |
RR indicates R-R interval; HR, Heart Rate; RRvar, RR variance; LFRR, low frequency power of RR variability; HFRR, high frequency power of RR variability; n.u., normalized units; LF/HF, ratio of the LF power to the HF one of RR series; SAP, Systolic Arterial Pressure; DAP, Diastolic Arterial Pressure; LFSAP, low frequency power of SAP variability; RESP, respiration rate; αLF, index of arterial baroreceptor sensitivity assessed by bivariate power spectrum analysis; NE, plasmatic norepinephrine; E, plasmatic epinephrine. Results are expressed as mean ± standard error. * p < 0.05 SUPINE vs. HUT.