ten Harkel A D, van Lieshout J J, Karemaker J M, Wieling W
Department of Medicine, Academic Medical Centre, Amsterdam, The Netherlands.
Clin Auton Res. 1993 Apr;3(2):117-24. doi: 10.1007/BF01818996.
We have determined if there are differences in normal subjects who fainted and those who did not faint during prolonged standing. We studied the short-term orthostatic responses in relation to heart rate, blood pressure measured by Finapres, left ventricular stroke volume analysed by pulse contour method, cardiac output and systemic vascular resistance, and also postural blood pressure and heart rate variability as assessed by spectral analysis. Thirteen healthy males without a history of syncope were studied. Three fainted after 10-13 min standing; the ten non-fainters remained upright for 20 min. The initial (first 30 s) postural circulatory adjustment was comparable for blood pressure but the rebound bradycardia was smaller in the fainters (heart rate at 22 s amounted to +13 +/- 10 beats/min above control vs. +1 +/- 5 beats/min in the non-fainters). Upright heart rate at 2 min standing was higher in the fainters (+31 +/- 2 beats/min vs. +20 +/- 5 beats/min), and blood pressure at 7 min standing was lower (-2/+5/+8 +/- 5/5/5 mmHg vs. +11/+13/+16 +/- 10/6/5 mmHg). The responses of stroke volume and cardiac output were comparable but systemic vascular resistance gradually decreased in the fainters from 5 min standing to the onset of fainting (+4 +/- 13% vs. +33 +/- 19% at 7 min standing). In fainters, the variability in upright blood pressure around 0.1 Hz was larger (8.8 mmHg2/Hz for diastolic blood pressure vs. 5.7 +/- 1.5 mmHg2/Hz in non-fainters).(ABSTRACT TRUNCATED AT 250 WORDS)
我们已确定在长时间站立过程中晕倒的正常受试者与未晕倒的正常受试者之间是否存在差异。我们研究了与心率、经Finapres测量的血压、通过脉搏轮廓法分析的左心室搏出量、心输出量和全身血管阻力相关的短期直立位反应，以及通过频谱分析评估的姿势性血压和心率变异性。对13名无晕厥病史的健康男性进行了研究。3人在站立10 - 13分钟后晕倒；10名未晕倒者保持直立姿势20分钟。最初（前30秒）的姿势性循环调节在血压方面具有可比性，但晕倒者的反弹性心动过缓较小（22秒时的心率比对照高 +13 ± 10次/分钟，而未晕倒者为 +1 ± 5次/分钟）。站立2分钟时晕倒者的直立位心率较高（+31 ± 2次/分钟 vs. +20 ± 5次/分钟），站立7分钟时血压较低（-2/+5/+8 ± 5/5/5 mmHg vs. +11/+13/+16 ± 10/6/5 mmHg）。搏出量和心输出量的反应具有可比性，但从站立5分钟到开始晕倒，晕倒者的全身血管阻力逐渐降低（站立7分钟时为 +4 ± 13% vs. +33 ± 19%）。在晕倒者中，0.1 Hz左右的直立位血压变异性更大（舒张压为8.8 mmHg2/Hz，而未晕倒者为5.7 ± 1.5 mmHg2/Hz）。（摘要截断于250字）
