HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 103/4/1128    most recent 00175.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Masuki, S. Articles by Joyner, M. J. Search for Related Content PubMed PubMed Citation Articles by Masuki, S. Articles by Joyner, M. J.

Reduced stroke volume during exercise in postural tachycardia syndrome

Departments of ¹Anesthesiology and ²Neurology, Mayo Clinic and Foundation, Rochester, Minnesota; and ³Department of Sports Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto, Japan

Submitted 11 February 2007 ; accepted in final form 5 July 2007

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 (R² = 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.

cardiac output; blood pressure; deconditioning; orthostatic intolerance