Stewart Julian M, Weldon Amy
Department of Pediatrics, New York Medical College, Valhalla, NY 10595, U.S.A.
Clin Sci (Lond). 2003 Apr;104(4):329-40.
Simple faint (neurocardiogenic syncope) and postural tachycardia syndrome (POTS) characterize acute and chronic orthostatic intolerance respectively. We explored the hypothesis that vascular function is similar in the two conditions. We studied 29 patients with POTS and compared them with 20 patients with neurocardiogenic syncope who were otherwise well, and with 15 healthy control subjects. We measured continuous heart rate, respiration and blood pressure, and used venous occlusion strain gauge plethysmography to measure calf and forearm blood flow, peripheral arterial resistance, peripheral venous resistance and venous pressure ( P (v)). Upright tilt was performed to 70 degrees for 10 min, during which calf blood flow and volume were measured. Calf P (v) was increased (to 27.2+/-2.0 mmHg) in a subgroup of POTS patients, who also had increased arterial resistance (57+/-6 mmHg.ml(-1).min(-1).100 ml(-1) tissue), increased venous resistance (2.4+/-0.3 mmHg.ml(-1).min(-1).100 ml(-1) tissue), and decreased peripheral flow (1.0+/-0.2 ml.min(-1).100 ml(-1) tissue) in the calf; other POTS patients with a normal P (v) had decreased arterial resistance (18+/-2 mmHg.ml(-1).min(-1).100 ml(-1) tissue) and increased blood flow (3.8+/-0.3 ml.min(-1).100 ml(-1) tissue). Syncope patients were not different from controls ( P (v)=11.4+/-0.5 mmHg; calf flow=3.1+/-0.2 ml.min(-1).100 ml(-1) tissue; arterial resistance=27+/-2 mmHg.ml(-1).min(-1).100 ml(-1) tissue; venous resistance=1.2+/-0.3 mmHg.ml(-1).min(-1).100 ml(-1) tissue). When upright, syncope patients and control subjects had similar increases in heart rate and calf volume, stable blood pressure, and decreases in blood flow. POTS patients had markedly increased heart rate and calf blood flow, unstable blood pressure, and pooling in the lower extremities, regardless of subgroup. We conclude that peripheral vascular physiology in patients with POTS is abnormal, in contrast with normal peripheral vascular physiology in neurocardiogenic syncope.
单纯性晕厥（神经心源性晕厥）和体位性心动过速综合征（POTS）分别为急性和慢性直立不耐受的特征。我们探讨了这两种情况血管功能相似的假说。我们研究了29例POTS患者，并将他们与20例无其他疾病的神经心源性晕厥患者以及15名健康对照者进行比较。我们连续测量心率、呼吸和血压，并使用静脉阻断应变计体积描记法测量小腿和前臂的血流量、外周动脉阻力、外周静脉阻力和静脉压（P（v））。将患者直立倾斜至70度并保持10分钟，在此期间测量小腿血流量和血容量。在一组POTS患者中，小腿P（v）升高（至27.2±2.0 mmHg），这些患者的动脉阻力也增加（57±6 mmHg·ml⁻¹·min⁻¹·100 ml⁻¹组织），静脉阻力增加（2.4±0.3 mmHg·ml⁻¹·min⁻¹·100 ml⁻¹组织），小腿外周血流量减少（1.0±0.2 ml·min⁻¹·100 ml⁻¹组织）；其他P（v）正常的POTS患者动脉阻力降低（18±2 mmHg·ml⁻¹·min⁻¹·100 ml⁻¹组织），血流量增加（3.8±0.3 ml·min⁻¹·100 ml⁻¹组织）。晕厥患者与对照组无差异（P（v）=11.4±0.5 mmHg；小腿血流量=3.1±0.2 ml·min⁻¹·100 ml⁻¹组织；动脉阻力=27±2 mmHg·ml⁻¹·min⁻¹·100 ml⁻¹组织；静脉阻力=1.2±0.3 mmHg·ml⁻¹·min⁻¹·100 ml⁻¹组织）。直立时，晕厥患者和对照者心率和小腿血容量的增加相似，血压稳定，血流量减少。无论亚组如何，POTS患者心率和小腿血流量显著增加，血压不稳定，下肢血液淤积。我们得出结论，与神经心源性晕厥正常的外周血管生理不同，POTS患者的外周血管生理异常。
