Department of Pediatrics, School of Medicine, Shahid Modarres Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Pediatrics, School of Medicine, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Pacing Clin Electrophysiol. 2021 Aug;44(8):1397-1403. doi: 10.1111/pace.14305. Epub 2021 Jul 10.
Head up Tilt-table Test (HUTT) is a practical examination of the most common type of pediatrics syncope. The electrocardiographic (ECG) changes during this test, show the autonomic defects that cause neuraly-mediated syncope in response to tilting process.
All pediatric syncope patients referred to our center in a 1-year period, were included in the study. HUTT was performed and patients were classified into two groups of Negative and Positive HUTT results, and the latter group was subclassified as three subgroups of "vasodepressor", "cardioinhibitory" and "mixed type" responses to HUTT. QT and corrected QT (QTc) dispersion was measured by the baseline standard 12-lead ECG obtained before HUTT.
Eighty-six patients with a mean age of 12.19 ± 5.34 were included. Patients with positive HUTT were significantly younger and male gender was more prevalent in this group. Mean QT dispersion was significantly higher in patients with positive HUTT result and also in patients with mixed response to HUTT compared to isolated vasodepressor response. Duration of QTc interval did not change between different study groups. Reciever-Operating-Characteristic (ROC) analysis showed that QT dispersion higher than 32 ms is a significant predictor of positive HUTT result (with 92% sensitivity and 98% specificity) and values higher than 40 ms can predict the mixed type of response to HUTT (with 84% sensitivity and 63% specificity).
Baseline myocardial repolarization disparity significantly correlates with susceptibility to symptomatic vasovagal syncope. This pathology seems to play its role mainly via excessive vagotonic response to sympathetic activation during HUTT process (known as cardioinhibitory response).
头高位倾斜试验（HUTT）是最常见儿科晕厥类型的实用检查。该试验过程中心电图（ECG）的变化显示了自主神经缺陷，这些缺陷导致神经介导的晕厥对倾斜过程产生反应。
在一年的时间内，将所有被转诊至我们中心的儿科晕厥患者纳入研究。进行 HUTT 检查，并将患者分为 HUTT 阴性和阳性结果两组，后者又分为“血管抑制型”、“心脏抑制型”和“混合型”三种亚组。使用 HUTT 前获得的标准 12 导联心电图测量 QT 和校正 QT（QTc）离散度。
共纳入 86 例患者，平均年龄为 12.19±5.34 岁。HUTT 阳性组患者明显更年轻，且男性更常见。HUTT 阳性组和混合型反应患者的 QT 离散度明显高于单纯血管抑制型反应患者。不同研究组之间 QTc 间期的持续时间没有变化。受试者工作特征（ROC）分析显示，QT 离散度高于 32ms 是 HUTT 阳性结果的显著预测指标（具有 92%的敏感性和 98%的特异性），而高于 40ms 的 QTc 离散度可以预测混合型反应（具有 84%的敏感性和 63%的特异性）。
基础心肌复极差异与症状性血管迷走性晕厥的易感性显著相关。这种病理变化似乎主要通过 HUTT 过程中交感神经激活引起的过度迷走神经反应（称为心脏抑制反应）发挥作用。
