Reduced stroke volume during exercise in postural tachycardia syndrome

Shizue Masuki, John H. Eisenach, William G. Schrage, Christopher P. Johnson, Niki M. Dietz, Brad W. Wilkins, Paola Sandroni, Phillip A. Low, Michael J. Joyner

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Postural tachycardia syndrome (POTS) is characterized by excessive tachycardia without hypotension during orthostasis. Most POTS patients also report exercise intolerance. To assess cardiovascular regulation during exercise in POTS, patients (n = 13) and healthy controls (n = 10) performed graded cycle exercise at 25, 50, and 75 W in both supine and upright positions while arterial pressure (arterial catheter), heart rate (HR; measured by ECG), and cardiac output (open-circuit acetylene breathing) were measured. In both positions, mean arterial pressure, cardiac output, and total peripheral resistance at rest and during exercise were similar in patients and controls (P > 0.05). However, supine stroke volume (SV) tended to be lower in the patients than controls at rest (99 ± 5 vs. 110 ± 9 ml) and during 75-W exercise (97 ± 5 vs. 111 ± 7 ml) (P = 0.07), and HR was higher in the patients than controls at rest (76 ± 3 vs. 62 ± 4 beats/min) and during 75-W exercise (127 ± 3 vs. 114 ± 5 beats/min) (both P < 0.01). Upright SV was significantly lower in the patients than controls at rest (57 ± 3 vs. 81 ± 6 ml) and during 75-W exercise (70 ± 4 vs. 94 ± 6 ml) (both P < 0.01), and HR was much higher in the patients than controls at rest (103 ± 3 vs. 81 ± 4 beats/min) and during 75-W exercise (164 ± 3 vs. 131 ± 7 beats/min) (both P < 0.001). The change (upright supine) in SV was inversely correlated with the change in HR for all participants at rest (R 2 = 0.32), at 25 W (R2 = 0.49), 50 W (R2 = 0.60), and 75 W (R2 = 0.32) (P < 0.01). These results suggest that greater elevation in HR in POTS patients during exercise, especially while upright, was secondary to reduced SV and associated with exercise intolerance.

Original languageEnglish (US)
Pages (from-to)1128-1135
Number of pages8
JournalJournal of applied physiology
Volume103
Issue number4
DOIs
StatePublished - Oct 2007

Keywords

  • Blood pressure
  • Cardiac output
  • Deconditioning
  • Orthostatic intolerance

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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    Masuki, S., Eisenach, J. H., Schrage, W. G., Johnson, C. P., Dietz, N. M., Wilkins, B. W., Sandroni, P., Low, P. A., & Joyner, M. J. (2007). Reduced stroke volume during exercise in postural tachycardia syndrome. Journal of applied physiology, 103(4), 1128-1135. https://doi.org/10.1152/japplphysiol.00175.2007