Figure 5. Head-up tilt test performed on 15-year-old-girl with suspected POTS. Please, note a steep increase in heart rate after tilt-up (+60 bpm) associated with subjective symptoms of orthostatic intolerance, headache, dizziness and fatigue. Cerebral oximetry (normal values: 60-80%) measured through near-infrared spectroscopy demonstrates pronounced variation and fall tendency. Test is terminated after 15 min due to pronounced intolerance symptoms.
