直立倾斜试验诱发QT间期缩短1例报告并文献复习

Head-up tilt test induced shortened QT interval:a case report and literature review

目的探讨继发性QT间期缩短的原因。方法回顾分析1例血管迷走性晕厥心脏抑制型患儿在直立倾斜试验中诱发QT间期缩短,同时复习相关文献。结果患儿,男,12岁,晨起刷牙时晕厥1次就诊。心电图示窦性心动过缓,心率55次/min,QT及QTc间期正常。动态心电图示窦性心律,平均心率70次/min,房性期前收缩3次,QT及QTc均值正常。彩色超声心动图示心脏内结构大致正常,左心室收缩功能正常。脑电图无异常。头颅CT无异常。空腹血糖5.2 mmol/L。基础直立倾斜试验为阳性,血管迷走性晕厥-心脏抑制型。直立倾斜试验过程中,动态心电图同步监测显示,患儿在直立倾斜16 min时出现窦性停搏,随即晕厥,窦性停搏分别为2.9 s和11.4 s,并行人工胸外按压。在出现窦性停搏之前可见QT间期缩短(QT=330 ms),QTc间期(按心率校正的QT间期=QT/(1/2)(RR))缩短(QTc=320 ms),QT/QTp=78%[QTp:QT间期预测值=656/(1+心率/100),正常QT间期的下限为QTp的88%]。结论迷走神经张力增高可诱发QT间期缩短。

Objective To explore the cause of secondary QT interval shortening.Method The data of a child with vasovagal syncope and cardiac depression in whom shortened QT interval was induced in head-up tilt test(HUTT)was analyzed retrospectively,and the related literatures were reviewed.Result A12-year-old boy visited for fainting when brushing his teeth in the morning.ECG showed sinus bradycardia,heart rate at55times/min and normal QT and QTc interval.Dynamic electrocardiogram showed sinus rhythm,mean heart rate at70times/min,atrial anterior contraction3times,normal mean QT and mean QTc.UCG showed approximately normal heart structure and the left ventricular systolic function.There was no abnormality in EEG and cranial CT.His fasting blood glucose was5.2mmol/L.The basal tilt test was positive with vasovagal syncope and cardiac depression.During the tilt table test,Holter monitoring showed that sinus arrest occurred in the child when upright tilt for16min,and then fainted.Time of sinus arrest was2.9s and11.4s,respectively,and artificial chest compressions were performed.The QT interval was shortened(QT=330ms),and so was QTc interval(QTc=320ms).The ratio of QT/QTp was78%(the lower limit of normal QT interval was88%of QTp)before sinus arrest occurred.Conclusion Increased vagal tone may induce QT interval shortening.