Diurnal pattern of QTc interval: How long is prolonged? Possible relation to circadian triggers of cardiovascular events
Diurnal pattern of QTc interval: How long is prolonged? Possible relation to circadian triggers of cardiovascular events
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DOI：
10.1016/0735-1097(95)00426-2
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发表时间：
1996-01-01
影响因子：
24
通讯作者：
Rosenthal, JE
中科院分区：
文献类型：
--
作者：
Molnar, J;Zhang, F;Rosenthal, JE
目标.本研究旨在评价24 h内QT和校正QT（QTc）间期的范围和变异性，并评估其模式及其与心率变异性的关系。最近的霍尔特监测数据显示QTc间期具有高度的每日变异性。这种变异性的模式及其与心率变异性的关系仍然很差的特点。我们开发并验证了一种新的方法，从三通道，24小时霍尔特记录连续测量QT间期。方法：收集21名健康受试者的5 min数据，测量其RR、QT、QTc和心率变异性。对6,048个节段的测量显示，平均（+/- SD）RR、QT和QTc间期分别为830 +/- 100、407 +/- 23和415 +/- 16 ms（男性平均QTc间期为434 +/- 12 ms，预兆为457 +/- 10 ms，p < 0.0001）。平均最大QTc间期为495 ± 21 ms，平均QTc范围为95 ± 20 ms。6例受试者的最大QTc间期大于或等于500 ms，13例受试者的最大QTc间期大于或等于490 ms。平均24 h QTc间期的95%置信上限为452 ms（男性439 ms，女性461 ms）。RR、QT和QTc间期以及心率变异性的高频成分在睡眠期间更大。QTc间期和每小时最小和最大QTc间期之间的变异性在觉醒后不久达到其昼夜节律峰值，然后下降到白天水平。正常人23小时以上的最大QTc间期比迄今认为的要长。QT和QTc间期在睡眠期间都较长。QTc间期和QTc变异性在觉醒后不久达到峰值，这可能反映了清醒早期自主神经不稳定性增加，峰值时间与报告的室性心动过速和心源性猝死易感性增加的时间段相对应。这些发现对QT间期延长的定义及其在预测心律失常和猝死中的应用具有一定的意义。
Objectives. This study sought to evaluate the range and variability of the QT and corrected QT (QTc) intervals over 24 h and to assess their pattern and relation to heart rate variability.Background. Recent Holter monitoring data have revealed a high degree of daily variability in the QTc interval. The pattern of this variability and its relation to heart rate variability remain poorly characterized.Methods. We developed and validated a new method for continuous measurement of QT intervals from three channel, 24-h Holter recordings. Average RR, QT, QTc and heart rate variability were measured from 5-min segments of data from 21 healthy subjects.Results. Measurement of 6,048 segments showed mean (+/- SD) RR, QT and QTc intervals of 830 +/- 100, 407 +/- 23 and 415 +/- 16 ms, respectively (mean QTc interval for men 434 +/- 12 ms, 457 +/- 10 ms for a omen, p < 0.0001). The average maximal QTc interval was 495 +/- 21 ms and the average QTc range 95 +/- 20 ms. The maximal QTc interval was greater than or equal to 500 ms in 6 subjects and greater than or equal to 490 ms in 13. The 95% upper confidence limit for the mean 24 h QTc interval was 452 ms (men 439 ms, women 461 ms). The RR, QT and QTc intervals and the high frequency component of heart rate variability were greater during sleep. Both the QTc interval and the variability between hourly minimal and maximal QTc intervals reached their circadian peak shortly after awakening, before declining to daytime levels.Conclusions. The maximal QTc interval over 23 h in normal subjects is longer than heretofore thought. Both QT and QTc intervals are longer during sleep. The QTc interval and QTc variability reach a peak shortly after awakening, which may reflect increased autonomic instability during early waking hours, and the time of the peak value corresponds in time to the period of reported increased vulnerability to ventricular tachycardia and sudden cardiac death. These findings have implications regarding the definition of QT prolongation and its use in predicting arrhythmias and sudden death.