Tutar H E, Ocal B, Imamoglu A, Atalay S
Department of Pediatric Cardiology, Faculty of Medicine, Ankara University, Turkey.
Heart. 1998 Jul;80(1):77-9. doi: 10.1136/hrt.80.1.77.
To determine the normal values of QT and QTc dispersion and the effects of sinus arrhythmia on QT dispersion in healthy children.
The study was carried out in a university hospital on 372 local schoolchildren (200 male, 172 female), aged seven to 18 years.
The QT and preceding RR intervals of at least one sinus beat were measured manually in a range of nine to 12 leads on standard 12 lead surface ECGs. The corrected QT interval was computed by the method of Bazett. Dispersion of QT and QTc were defined as (1) the difference between the maximum and minimum QT and QTc intervals occurring in any of the 12 leads (QTD and QTcD), (2) the standard deviation of the QT and QTc interval in the measurable leads (QT-SD and QTc-SD).
There was no significant difference in QT, QTc, and RR dispersion between girls and boys. Overall 53% of children had sinus arrhythmia. Although QTD and QT-SD were not affected by sinus arrhythmia, both QTcD and QTc-SD were significantly greater in children with sinus arrhythmia than in those without (QTcD: 52.9 (17.4) v 40.9 (13.1); QTc-SD: 17.5 (5.9) v 13.2 (4.0); p < 0.001).
As calculation of QTc dispersion is affected by sinus arrhythmia, which is common in childhood, we suggest that QT dispersion should not be corrected for heart rate in children.
确定健康儿童QT和QTc离散度的正常值以及窦性心律失常对QT离散度的影响。
本研究在一所大学医院对372名当地学童（200名男性，172名女性）进行，年龄在7至18岁之间。
在标准12导联体表心电图的9至12个导联范围内，手动测量至少一个窦性心搏的QT间期及之前的RR间期。采用Bazett法计算校正QT间期。QT和QTc离散度定义为：（1）12个导联中任一导联出现的最大和最小QT及QTc间期之差（QTD和QTcD）；（2）可测量导联中QT和QTc间期的标准差（QT-SD和QTc-SD）。
女孩和男孩的QT、QTc及RR离散度无显著差异。总体而言，53%的儿童有窦性心律失常。虽然QTD和QT-SD不受窦性心律失常影响，但窦性心律失常儿童的QTcD和QTc-SD均显著高于无窦性心律失常的儿童（QTcD：52.9（17.4）对40.9（13.1）；QTc-SD：17.5（5.9）对13.2（4.0）；p<0.001）。
由于QTc离散度的计算受窦性心律失常影响，而窦性心律失常在儿童期很常见，我们建议儿童不应进行心率校正的QT离散度计算。
