A Case with Postural Tachycardia Syndrome.

Postural tachycardia syndrome (POTS) has recently been recognized as a syndrome in which patients have an increased heart rate without orthostatic hypotension. Patients with POTS may complain of presyncope, vertigo, dizziness, light-headedness, general fatigue or unsteadiness. However, the etiology of POTS is unclear. We report a typical case of POTS; a 24 year-old woman who had suffered from dizzy sensations during postural changes for six months. No abnormalities had been observed in ECG, echocardiography, clinical chemistry, blood test and brain MRI. On the first visit, no abnormal responses were noted on neuro-otological examinations or for the CMI and SRQ; D psychological questionnaires. However, the patient's heart rate increased by 34 beats/min from supine to standing position, and in addition, she complained of a headache and fatigue without hypotension during Schellong test. Power spectral analysis of RR interval variability during Schellong test revealed that the normalized powers of low frequency (LFnp) and ratio of LF and high frequency powers (LF/HF) increased when standing upright from supine position. We diagnosed her with POTS and administered atenolol (β1 blocker, 50mg every morning) in formula, which markedly reduced her subjective symptoms.