The main limitation patients with orthostatic intolerance (OI, or postural tachycardia
syndrome, POTS) have to exercise is related to their increase in heart rate when standing.
Main pharmacological treatment today is aimed at reducing heart rate with the use of
betablockers (propanolol), this theoretically could also improve their exercise capacity; if
their heart rate do not increase as much with the medication, they could exercise more. In
addition, it has been suggested that in healthy volunteers subjected to head down tilt for 2
weeks (situation that produces a "simulated" transient POTS-like state) a single bout of
intense exercise can improve orthostatic tolerance the day after exercising. The mechanisms
involved in such response are not that clear but could be an increase in plasma volume
already diminished in POTS patients. It seems likely that the same could be true for POTS
patients.
The purpose of the present study are to pharmacologically improve the amount of exercise POTS
patients can perform by reducing their baseline heart rate (specific aim 1) and to evaluate
next day heart responses to an acute bout of intense exercise.
Therefore, the specific aims of this study are:
1. To test the hypothesis that lowering heart rate response with propanolol will result in
an increase in exercise capacity.
2. To test the hypothesis that a single bout of exercise will result in an improvement in
orthostatic tolerance the day after exercising.
Phase:
N/A
Details
Lead Sponsor:
Vanderbilt University Vanderbilt University Medical Center