Stewart Julian M, Medow Marvin S, Montgomery Leslie D
Department of Pediatrics, Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA.
Am J Physiol Heart Circ Physiol. 2003 Dec;285(6):H2749-56. doi: 10.1152/ajpheart.00429.2003. Epub 2003 Aug 14.
Postural tachycardia syndrome (POTS) is defined by orthostatic intolerance associated with abnormal upright tachycardia. Some patients have defective peripheral vasoconstriction and increased calf blood flow. Others have increased peripheral arterial resistance and decreased blood flow. In 14 POTS patients (13-19 yr) evenly subdivided among low-flow POTS (LFP) and high-flow POTS (HFP) we tested the hypothesis that myogenic, venoarteriolar, and reactive hyperemic responses are abnormal. We used venous occlusion plethysmography to measure calf venous pressure and blood flow in the supine position and when the calf was lowered by 40 cm to evoke myogenic and venoarteriolar responses and during venous hypertension by 40-mmHg occlusion to evoke the venoarteriolar response. We measured calf reactive hyperemia with plethysmography and cutaneous laser-Doppler flowmetry. Baseline blood flow in LFP was reduced compared with HFP and control subjects (0.8 +/- 0.2 vs. 4.4 +/- 0.5 and 2.7 +/- 0.4 ml.min-1.100 ml-1) but increased during leg lowering (1.2 +/- 0.5 ml.min-1. 100 ml-1) while decreasing in the others. Baseline peripheral arterial resistance was increased in LFP and decreased in HFP compared with control subjects (39 +/- 13 vs. 15 +/- 3 and 22 +/- 5 mmHg.ml-1. 100 ml. min) but decreased to 29 +/- 13 mmHg.ml-1.100 ml. min in LFP during venous hypertension. Resistance increased in the other groups. Maximum calf hyperemic flow and cutaneous flow were similar in all subjects. The duration of hyperemic blood flow was curtailed in LFP compared with either control or HFP subjects (plethysmographic time constant = 20 +/- 2 vs. 29 +/- 4 and 28 +/- 4 s; cutaneous time constant = 60 +/- 25 vs. 149 +/- 53 s in controls). Local blood flow regulation in low-flow POTS is impaired.
体位性心动过速综合征（POTS）的定义是与异常直立性心动过速相关的体位不耐受。一些患者存在外周血管收缩功能缺陷且小腿血流量增加。另一些患者外周动脉阻力增加且血流量减少。在14名年龄在13至19岁之间的POTS患者中，平均分为低流量POTS（LFP）组和高流量POTS（HFP）组，我们检验了肌源性、静脉动脉分流和反应性充血反应异常的假设。我们使用静脉阻断体积描记法测量仰卧位以及将小腿降低40厘米以诱发肌源性和静脉动脉分流反应时小腿的静脉压和血流量，并在通过40毫米汞柱阻断诱发静脉动脉分流反应的静脉高压期间进行测量。我们用体积描记法和皮肤激光多普勒血流仪测量小腿反应性充血。与HFP组和对照组相比，LFP组的基线血流量降低（0.8±0.2 vs. 4.4±0.5和2.7±0.4毫升·分钟-1·100毫升-1），但在小腿降低时增加（1.2±0.5毫升·分钟-1·100毫升-1），而其他组则减少。与对照组相比，LFP组的基线外周动脉阻力增加，HFP组降低（39±13 vs. 15±3和22±5毫米汞柱·毫升-1·100毫升·分钟），但在静脉高压期间LFP组降至29±13毫米汞柱·毫升-1·100毫升·分钟。其他组的阻力增加。所有受试者的最大小腿充血流量和皮肤流量相似。与对照组或HFP组相比，LFP组充血血流的持续时间缩短（体积描记时间常数 = 20±2 vs. 29±4和28±4秒；对照组皮肤时间常数 = 60±25 vs. 149±53秒）。低流量POTS患者的局部血流调节受损。
