Goldstein David S, Eldadah Basil, Holmes Courtney, Pechnik Sandra, Moak Jeffrey, Sharabi Yehonatan
Clinical Neurocardiology Section, NINDS, National Institutes of Health, Bethesda, Md, USA.
Circulation. 2005 Feb 22;111(7):839-45. doi: 10.1161/01.CIR.0000155613.20376.CA. Epub 2005 Feb 7.
Chronic orthostatic intolerance (COI) occurs in postural tachycardia syndrome (POTS) and in some individuals with repeated neurocardiogenic syncope/presyncope (NCS), without POTS. This study addressed whether patients with COI and POTS or NCS have neurocirculatory abnormalities during supine rest.
Adult patients referred for COI who had POTS (n=90, mean+/-SEM age 40+/-1 years, 86% women) or NCS (n=36, 41+/-2 years old, 78% women) underwent measurements of plasma levels of catecholamines and forearm hemodynamics. Comparison data were obtained from 32 age- and gender-matched normal volunteers (39+/-2 years old, 81% women). The POTS group had a relatively fast mean heart rate (79+/-2 bpm) during supine rest compared with the NCS group (69+/-1.6 bpm, P=0.03) and normal volunteers (66+/-3 bpm, P=0.0004). The POTS group also had higher mean arterial norepinephrine (1.61+/-0.11 nmol/L, n=37) and epinephrine (0.39+/-0.03 nmol/L, n=37) concentrations than the NCS group (1.03+/-0.12 nmol/L, n=20, P=0.0012; 0.21+/-0.03 nmol/L, n=20, P=0.0005) and normal volunteers (1.13+/-0.11 nmol/L, n=20, P=0.006; 0.17+/-0.03 nmol/L, n=15, P=0.0001). The NCS group had higher mean forearm vascular resistance (52+/-6 U) than the POTS group (36+/-2 U, P=0.003).
Overall, POTS features increased heart rate and sympathetic nervous and adrenomedullary hormonal system outflows during supine rest. Increased sympathetic outflow may contribute to the relative tachycardia in POTS. NCS features forearm vasoconstriction during supine rest but not sympathoneural or adrenomedullary activation.
慢性直立不耐受（COI）发生于体位性心动过速综合征（POTS）以及一些反复出现神经心源性晕厥/先兆晕厥（NCS）但无POTS的个体中。本研究探讨了患有COI和POTS或NCS的患者在仰卧休息时是否存在神经循环异常。
因COI前来就诊的成年患者中，患有POTS的患者（n = 90，平均±标准误年龄40±1岁，86%为女性）或NCS的患者（n = 36，41±2岁，78%为女性）接受了儿茶酚胺血浆水平和前臂血流动力学测量。比较数据来自32名年龄和性别匹配的正常志愿者（39±2岁，81%为女性）。与NCS组（69±1.6次/分，P = 0.03）和正常志愿者（66±3次/分，P = 0.0004）相比，POTS组在仰卧休息时平均心率相对较快（79±2次/分）。POTS组的平均动脉去甲肾上腺素（1.61±0.11 nmol/L，n = 37）和肾上腺素（0.39±0.03 nmol/L，n = 37）浓度也高于NCS组（1.03±0.12 nmol/L，n = 20，P = 0.0012；0.21±0.03 nmol/L，n = 20，P = 0.0005）和正常志愿者（1.13±0.11 nmol/L，n = 20，P = 0.006；0.17±0.03 nmol/L，n = 15，P = 0.0001）。NCS组的平均前臂血管阻力（52±6 U）高于POTS组（36±2 U，P = 0.003）。
总体而言，POTS的特征是仰卧休息时心率增加以及交感神经和肾上腺髓质激素系统的输出增加。交感神经输出增加可能导致POTS中的相对心动过速。NCS的特征是仰卧休息时前臂血管收缩，但不存在交感神经或肾上腺髓质激活。
