Stewart Julian M, Taneja Indu, Medow Marvin S
Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA.
Clin Sci (Lond). 2007 Dec;113(11):449-57. doi: 10.1042/CS20070104.
Altered peripheral haemodynamics, decreased cardiac output, decreased blood volume and increased AngII (angiotensin II) have been reported in POTS (postural tachycardia syndrome). Recent findings indicate that BMI (body mass index) may be reduced. In the present study, we investigated the hypothesis that reduced BMI is associated with haemodynamic abnormalities in POTS and that this is related to AngII. We studied 52 patients with POTS, aged 14-29 years, compared with 36 control subjects, aged 14-27 years. BMI was not significantly reduced on average in the POTS patients, but was reduced in patients with decreased peripheral blood flow. POTS patients were then subdivided on the basis of BMI, and supine haemodynamics were measured. There was no difference in blood volume or cardiac output once BMI or body mass were accounted for. When POTS patients with BMI <50th percentile were compared with controls, calf blood flow [1.63+/-0.31 compared with 3.58+/-0.67 ml(-1).min(-1).(100 ml of tissue)(-1)] and maximum venous capacity (3.87+/-0.32 compared with 4.98+/-0.36 ml/100 ml of tissue) were decreased, whereas arterial resistance [56+/-0.5 compared with 30+/-4 mmHg.ml(-1).min(-1).(100 ml of tissue)(-1)] and venous resistance [1.23+/-0.17 compared with 0.79+/-0.11 mmHg.ml(-1).min(-1).(100 ml of tissue)(-1)] were increased. Similar findings were also observed when POTS patients with BMI <50th percentile were compared with POTS patients with BMI >50th percentile. There was no relationship between blood flow, resistance or maximum venous capacity with BMI in control subjects. BMI was inversely related to plasma AngII concentrations in those POTS patients with decreased peripheral blood flow, consistent with cachectic properties of the octapeptide. Patients with low-flow POTS had decreased body mass, but decreased body mass alone cannot account for findings of peripheral vasoconstriction. In conclusion, the findings suggest that reduced body mass relates to increased plasma AngII.
体位性心动过速综合征（POTS）患者存在外周血流动力学改变、心输出量降低、血容量减少以及血管紧张素II（AngII）升高的情况。近期研究结果表明，体重指数（BMI）可能降低。在本研究中，我们探讨了BMI降低与POTS血流动力学异常相关且与AngII有关这一假说。我们研究了52例年龄在14 - 29岁的POTS患者，并与36例年龄在14 - 27岁的对照者进行比较。POTS患者的平均BMI无显著降低，但外周血流减少的患者BMI降低。然后根据BMI对POTS患者进行细分，并测量仰卧位血流动力学。在考虑BMI或体重后，血容量或心输出量并无差异。当将BMI低于第50百分位数的POTS患者与对照者比较时，小腿血流量[分别为1.63±0.31与3.58±0.67 ml(-1).min(-1).(100 ml组织)(-1)]和最大静脉容量（分别为3.87±0.32与4.98±0.36 ml/100 ml组织）降低，而动脉阻力[分别为56±0.5与30±4 mmHg.ml(-1).min(-1).(100 ml组织)(-1)]和静脉阻力[分别为1.23±0.17与0.79±0.11 mmHg.ml(-1).min(-1).(100 ml组织)(-1)]升高。当将BMI低于第50百分位数的POTS患者与BMI高于第50百分位数的POTS患者比较时，也观察到类似结果。对照者的血流量、阻力或最大静脉容量与BMI之间无相关性。在那些外周血流减少的POTS患者中，BMI与血浆AngII浓度呈负相关，这与该八肽的恶病质特性一致。低流量POTS患者体重降低，但仅体重降低不能解释外周血管收缩的结果。总之，研究结果表明体重降低与血浆AngII升高有关。
