Continuous progression of orthostatic tachycardia as a further feature of the postural tachycardia syndrome.
BACKGROUND
The clinical diagnosis of the postural tachycardia syndrome (POTS) includes the demonstration of an upright heart rate (HR) of at least 30 beats per minute (bpm) above supine HR. The dynamic behavior of HR during the course of standing has not yet been studied systematically in POTS.


METHODS
HR and arterial blood pressure (ABP) were continuously monitored in 17 POTS patients and in 24 age-matched controls at rest and during an 11-minute phase of 80 degrees tilt.


RESULTS
ABP values at different time intervals of the protocol did not differ between the subgroups with the exception of higher diastolic pressures in POTS after 5 and 10 minutes of tilt. POTS patients showed a higher resting HR (80.6 +/- 17.0 bpm vs 67.8 +/- 10.9 bpm in controls, P < 0.05) and there was a continuous HR acceleration in the course of the 11-minute tilt phase. In control subjects, the tilt-induced HR increase was nearly completed after 1 minute with only a minimal further rise between minute 1 and minute 10 (from 83.7 +/- 11.5 to 85.3 +/- 11.9 bpm vs from 106.1 +/- 15.6 to 120.1 +/- 13.8 bpm in POTS).


CONCLUSIONS
Continuously progressing orthostatic tachycardia can serve as an additional criterion in the diagnosis of POTS. It may be related to the recently observed increased orthostatic capillary filtration rate in POTS.
Diehl
Rolf R
RR
Autonomic Laboratory, Department of Neurology, Krupp Hospital, Alfried-Krupp-Strasse 21, 45117 Essen, Germany. Rolf.Diehl@Krupp-Krankenhaus.de
D000328:Adult; D016022:Case-Control Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D018709:Statistics, Nonparametric; D013577:Syndrome; D013610:Tachycardia / Q000175:diagnosis* / Q000503:physiopathology*; D018667:Tilt-Table Test