Syncope is a common and often benign disorder presenting at the pediatric emergency department. Long-QT syndrome may be presented with syncope, ventricular arrhythmias or sudden death and is vital to exclude as an underlying cause in children presented with syncope. Few studies have assessed QTc in relation to body posture in children. In this study, we assessed the QTc interval while laying down and during active standing in children with known long-QT syndrome compared to healthy controls. Children aged 1–18 years with long-QT syndrome (N = 17) matched to two healthy controls (N = 34) were included in this case-control study. The ECG standing was performed immediately after the ECG in the supine position. The QTc interval and QTc-difference by changing the body position were calculated. All children with long-QT syndrome were treated with propranolol. QTc was prolonged among long-QT syndrome children while lying down and when standing up, compared to controls. A prolongation of QTc appeared when standing up for both cases and controls. There was no significant difference in QTc increase between the groups. A QTc over 440 ms was observed among four cases lying down and in eight cases while standing, but not in any of the controls. The standing test with a cut-off of 440 ms showed a sensitivity of 47% and a specificity of 100% for case-status in our study. QTc measured on ECG when rapidly rising up is prolonged in both healthy and LQTS children. More importantly, it prolongs more in children with LQTS and increases in pathological levels.

中文翻译：

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QTc间隔依赖于儿科的身体姿势

晕厥是小儿急诊科常见的良性疾病。Long-QT综合征可能伴有晕厥，室性心律不齐或猝死，对于排除因晕厥而患儿的根本原因至关重要。很少有研究评估QTc与儿童身体姿势有关。在这项研究中，我们评估了已知长QT综合征儿童与健康对照组相比，在躺下和积极站立时的QTc间隔。该病例对照研究包括1-18岁的长QT综合征（N = 17）与两个健康对照（N = 34）匹配的儿童。心电图仰卧后立即进行心电图站立。通过改变身体位置来计算QTc间隔和QTc差。所有患有长QT综合征的儿童均接受普萘洛尔治疗。与对照组相比，长时间QT综合症患儿在躺下和站立时QTc延长。站立时对病例和对照者均出现QTc延长。两组之间的QTc增加无显着差异。在躺下的四个病例和站立时的八个病例中观察到超过440毫秒的QTc，但没有任何对照。在我们的研究中，截断时间为440毫秒的站立测试显示出47％的敏感性和100％的特异性。健康儿童和LQTS儿童在快速上升时在ECG上测量的QTc延长。更重要的是，它在患有LQTS的儿童中延长了更多时间，并增加了病理水平。与控件相比。站立时对病例和对照者均出现QTc延长。两组之间的QTc增加无显着差异。在躺下的四个病例和站立时的八个病例中观察到超过440毫秒的QTc，但没有任何对照。在我们的研究中，截断时间为440毫秒的站立测试显示出47％的敏感性和100％的特异性。健康儿童和LQTS儿童在快速上升时在ECG上测量的QTc延长。更重要的是，它在患有LQTS的儿童中延长了更多时间，并增加了病理水平。与控件相比。站立时对病例和对照者均出现QTc延长。两组之间的QTc增加无显着差异。在躺下的四个病例和站立时的八个病例中观察到超过440毫秒的QTc，但没有任何对照。在我们的研究中，截断时间为440毫秒的站立测试显示出47％的敏感性和100％的特异性。健康儿童和LQTS儿童在快速上升时在ECG上测量的QTc延长。更重要的是，它在患有LQTS的儿童中延长了更多时间，并增加了病理水平。在躺下的四个病例和站立时的八个病例中观察到超过440毫秒的QTc，但没有任何对照。在我们的研究中，截断时间为440毫秒的站立测试显示出47％的敏感性和100％的特异性。健康儿童和LQTS儿童在快速上升时在ECG上测量的QTc延长。更重要的是，它在患有LQTS的儿童中延长了更多时间，并增加了病理水平。在躺下的四个病例和站立时的八个病例中观察到超过440毫秒的QTc，但没有任何对照。在我们的研究中，截断时间为440毫秒的站立测试显示出47％的敏感性和100％的特异性。健康儿童和LQTS儿童在快速上升时在ECG上测量的QTc延长。更重要的是，它在患有LQTS的儿童中延长了更多时间，并增加了病理水平。