Fig. 1.
Local heating response in a representative normal-flow postural tachycardia syndrome (POTS) patient (gray) and in a healthy volunteer control subject (black). Key points along the curve are marked. The heat response plateau, dependent on bioavailable nitric oxide (NO), is near maximum vasodilation in POTS patients, whereas the response in control subjects is significantly smaller. %CVCmax, percent maximum cutaneous vascular conductance.