The authors present a case of 36 year old male patient with idiopathic postural orthostatic
tachycardia syndrome (POTS) diagnosed during head-up tilt testing. Power spectral
analysis of heart rate variability (HRV) during the tilt test revealed that the ratio of low and high frequency
powers (LF/HF) increased with the onset of orthostatic intolerance. This analysis confirmed
in our patient a strong activation in sympathetic tone. (Heart International 2006; 2: 126-8)