Differences in cardiac autonomic function contributes to heart rate abnormalities in POTS and IST.

Our objective was to examine the differences in cardiac autonomic function in Postural Tachycardia Syndrome (POTS) versus inappropriate sinus tachycardia (IST). Subjects (IST, n = 8; POTS, n = 12) were studied using standard measurements of the autonomic reflex screen, baroreflex function and spectral analysis. Data was compared to age/gender-matched controls (n = 20).

A prospective study of excessive postural heart rate change on head-up tilt.

Purpose: Healthy subjects with asymptomatic postural tachycardia (≥30 bpm) at baseline were evaluated over a 1-year period to determine whether they developed orthostatic symptoms.

Methods: Subjects were evaluated at baseline and at 1 year using the autonomic reflex screen and autonomic symptom profile (ASP).

Results: Heart rate increment on HUT did not differ at baseline (40.