Table 2.
Baseline Characteristics in Female Patients With POTS and Control Subjects
| Control Subjects (n = 11) |
Patients With POTS (n = 25) |
SMD | P Value | |
|---|---|---|---|---|
| Demographics | ||||
| Age, y | 31 ± 7 | 31 ± 8 | 0.11 | 0.76 |
| Height, cm | 163 ± 4 | 167 ± 9 | 0.62 | 0.10 |
| Weight, kg | 62.0 ± 5.2 | 67.5 ± 8.7 | 0.71 | 0.059 |
| Body mass index, kg/m2 | 23.5 ± 2.3 | 24.3 ± 3.9 | 0.23 | 0.53 |
| Medications (held/prescribed) | ||||
| Beta-blockers | NA | 11/17 | NA | |
| Midodrine | NA | 3/9 | NA | |
| Fludrocortisone | NA | 0/2 | NA | |
| Ivabradine | NA | 1/2 | NA | |
| Sympatholytic | NA | 5/6 | NA | |
| Pyridostigmine | NA | 1/2 | NA | |
| Ventilatory | ||||
| Ventilation, L/min | 10.1 ± 2.0 | 9.2 ± 2.6 | 0.35 | 0.34 |
| End-tidal CO2, mm Hg | 39.5 ± 2.9 | 38.0 ± 3.8 | 0.42 | 0.26 |
| End-tidal O2, mm Hg | 90.4 ± 5.0 | 92.5 ± 7.0 | 0.32 | 0.39 |
| Peripheral hemodynamics | ||||
| Heart rate, beats/min | 69 ± 9 | 71 ± 13 | 0.13 | 0.72 |
| Stroke volume, mL | 78 ± 12 | 79 ± 15 | 0.05 | 0.89 |
| Cardiac output, L/min | 5.4 ± 0.7 | 5.6 ± 1.1 | 0.18 | 0.62 |
| Mean arterial pressure, mm Hg | 91 ± 12 | 91 ± 13 | 0.01 | 0.97 |
| Systemic vascular resistance, dynes/cm5 | 1,920 ± 695 | 1,671 ± 557 | 0.41 | 0.26 |
| Pulse pressure, mm Hg | 66 ± 9 | 63 ± 11 | 0.32 | 0.38 |
| Arterial pulsatility index | 0.73 ± 0.1 | 0.69 ± 0.1 | 0.39 | 0.29 |
| Cerebral hemodynamics | ||||
| MCAvmean, cm/s | 85 ± 10 | 78 ± 13 | 0.62 | 0.094 |
| MCAvpeak, cm/s | 123 ± 14 | 114 ± 18 | 0.57 | 0.12 |
| MCAvmin, cm/s | 66 ± 8 | 60 ± 11 | 0.63 | 0.093 |
| MCAv pulsatility index | 0.68 ± 0.1 | 0.70 ± 0.1 | 0.26 | 0.48 |
| Sympathetic | (n = 9) | (n = 12) | ||
| Burst frequency, bursts/min | 15 ± 6 | 13 ± 5 | 0.51 | 0.26 |
| Burst amplitude, % of peak | 40 ± 9 | 41 ± 14 | 0.12 | 0.78 |
| Total MSNA, AU/min | 645 ± 312 | 566 ± 320 | 0.25 | 0.58 |
Values are mean ± SD. Group differences were compared using an independent-samples 2-tailed Student’s t-test.
AU = arbitrary units; MCAv = middle cerebral artery velocity; MSNA = muscle sympathetic nerve activity; NA = not applicable; POTS = postural orthostatic tachycardia syndrome; SMD = standardized mean difference.