Journal
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
Volume 289, Issue 3, Pages H1226-H1233Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.01243.2004
Keywords
intolerance; blood pressure; heart rate; Valsalva maneuver; head-up tilt
Funding
- NCRR NIH HHS [RR-00585] Funding Source: Medline
- NICHD NIH HHS [T32 HD-07447-11] Funding Source: Medline
- NINDS NIH HHS [NS-44233, NS-39722, NS-32352] Funding Source: Medline
Ask authors/readers for more resources
Postural orthostatic tachycardia syndrome ( POTS) is characterized by excessive tachycardia during orthostasis. To test the hypothesis that patients with POTS have decreased sympathetic neural responses to baroreflex stimuli, we measured heart rate (HR) and muscle sympathetic nerve activity (MSNA) responses to three baroreflex stimuli including vasoactive drug boluses (modified Oxford technique), Valsalva maneuver, and head-up tilt ( HUT) in POTS patients and healthy control subjects. The MSNA response to the Valsalva maneuver was significantly greater in the POTS group ( controls, 26 +/- 7 vs. POTS, 48 +/- 6% of baseline MSNA/mmHg; P = 0.03). POTS patients also had an exaggerated MSNA response to 30 degrees HUT ( controls, 123 +/- 24 vs. POTS, 208 +/- 30% of baseline MSNA; P = 0.03) and tended to have an exaggerated response to 45 HUT ( controls, 137 +/- 27 vs. POTS, 248 +/- 58% of baseline MSNA; P = 0.10). Sympathetic baroreflex sensitivity calculated during administration of the vasoactive drug boluses also tended to be greater in the POTS patients; however, this did not reach statistical significance ( P = 0.15). Baseline MSNA values during supine rest were not different between the groups (controls, 23 +/- 4 vs. POTS, 16 +/- 5 bursts/100 heartbeats; P = 0.30); however, resting HR was significantly higher in the POTS group (controls, 58 +/- 3 vs. POTS, 82 +/- 4 beats/min; P = 0.0001). Our results suggest that POTS patients have exaggerated MSNA responses to baroreflex challenges compared with healthy control subjects, although resting supine MSNA values did not differ between the groups.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available