Reduced stroke volume during exercise in postural tachycardia syndrome
Reduced stroke volume during exercise in postural tachycardia syndrome
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DOI：
10.1152/japplphysiol.00175.2007
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发表时间：
2007-10-01
影响因子：
3.3
通讯作者：
Joyner, Michael J.
中科院分区：
文献类型：
--
作者：
Masuki, Shizue;Eisenach, John H.;Joyner, Michael J.
心动过速后综合征（POTS）的特征是体位性心动过速而无低血压。大多数POTS患者也报告运动不耐受。为了评估POTS患者运动期间的心血管调节，患者（n = 13）和健康对照组（n = 10）在仰卧位和直立位以25、50和75 W进行分级循环运动，同时测量动脉压（动脉导管）、心率（HR;通过ECG测量）和心输出量（开路乙炔呼吸）。在两种体位下，患者和对照组在静息和运动时的平均动脉压、心输出量和总外周阻力相似（P > 0.05）。然而，患者的仰卧位每搏输出量（SV）在静息时往往低于对照组（99 +/- 5 vs. 110 +/- 9 ml）和75 W运动期间（97 +/- 5 vs. 111 +/- 7 ml）（P 0.07），静息时患者的HR高于对照组（76 +/- 3 vs. 62 +/- 4 beats/min）和75 W运动期间（127 +/- 43 vs. 114 5 beats/min）（均P < 0.01）。静息时患者的直立SV显著低于对照组（57 +/- 3 vs. 81 +/- 6 ml）和75 W运动期间（70 +/- 4- 4 vs. 94 +/- 6 ml）（均P < 0.01），静息时患者的HR比对照组高得多（103 3对81 +/- 4次/分）和在75 W运动期间（164 +/- 3对131 +/- 7次/分）（均P < 0.001）。所有受试者在静息（R-2 = 0.32）、25 W（R-2 = 0.49）、50 W（R-2 = 0.60）和75 W（R-2 = 0.32）时SV的变化（直立-仰卧）与HR的变化呈负相关（P < 0.01）。这些结果表明，POTS患者在运动期间，尤其是直立时，HR升高更大，继发于SV减少，并与运动不耐受相关。
PosturaI 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 +/- 43 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- 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 (R-2 = 0.49), 50 W (R-2 = 0.60), and 75 W (R 2 = 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.