Cardiac Center, Nemours Children's Health, 6535 Nemours Parkway, Orlando, FL, 32827, USA.
College of Medicine, University of Central Florida, Orlando, FL, USA.
Pediatr Cardiol. 2023 Aug;44(6):1358-1366. doi: 10.1007/s00246-023-03113-0. Epub 2023 Feb 8.
Low left ventricular mass index (LVMI) is thought to limit exercise tolerance in adult patients with postural orthostatic tachycardia syndrome (POTS). This finding has not been studied in children. We evaluated the effect of LVMI and hemodynamics at baseline and during exercise in POTS versus controls. POTS and control subjects aged 12-18 years were prospectively enrolled. POTS patients underwent autonomic studies. An echocardiogram was performed on all patients at baseline and during exercise. LVMI, venous return from inferior vena cava (IVC-VTI), left ventricular dimension, and cardiac output were assessed at baseline and during exercise. Generalized linear modeling with mixed effects was used to perform repeated measures testing between POTS and controls. Eighteen POTS patients (14 female, aged 15.4 ± 1.4 years) and nine control subjects (six female, aged 15.0 ± 1.3 years; p = 0.44) were enrolled. At baseline, LVMI was similar in both groups. During exercise, IVC-VTI, left ventricular end-diastolic dimension and volume, and stroke volume were lower in POTS patients. Peak heart rate was higher in POTS patients, but cardiac output was similar in both groups. Exercise time was higher in the control group (11.4 ± 2.7 min vs 9.2 ± 2.1, p = 0.024). Lower venous return resulted in smaller cardiac dimension and stroke volume during exercise. Higher heart rate in POTS may compensate to achieve similar cardiac output compared with control subjects. Lower ventricular filling and earlier time to peak heart rate may explain lower exercise capacity in pediatric POTS.
左心室质量指数（LVMI）较低被认为会限制体位性心动过速综合征（POTS）成年患者的运动耐量。这一发现尚未在儿童中进行研究。我们评估了 LVMI 和血流动力学在 POTS 与对照组中的基线和运动时的影响。12-18 岁的 POTS 和对照组患者前瞻性入组。POTS 患者接受自主神经研究。所有患者在基线和运动时均进行超声心动图检查。在基线和运动时评估 LVMI、下腔静脉（IVC-VTI）静脉回流、左心室尺寸和心输出量。使用具有混合效应的广义线性模型进行重复测量检验。共纳入 18 例 POTS 患者（14 例女性，年龄 15.4±1.4 岁）和 9 例对照组患者（6 例女性，年龄 15.0±1.3 岁；p=0.44）。基线时，两组的 LVMI 相似。在运动过程中，POTS 患者的 IVC-VTI、左心室舒张末期尺寸和容积以及每搏输出量较低。POTS 患者的峰值心率较高，但心输出量在两组间相似。对照组的运动时间较高（11.4±2.7 分钟比 9.2±2.1 分钟，p=0.024）。较低的静脉回流导致运动时心脏尺寸和每搏输出量较小。POTS 患者较高的心率可能会代偿以达到与对照组相似的心输出量。较低的心室充盈和更早达到峰值心率可能解释了儿科 POTS 运动能力较低的原因。
