Ireland R H, Robinson R T, Heller S R, Marques J L, Harris N D
Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital, University of Sheffield, UK.
Physiol Meas. 2000 May;21(2):295-303. doi: 10.1088/0967-3334/21/2/309.
During hypoglycaemia, typically there is a change in the surface ECG characterized by a flattened and prolonged T wave, often accompanied by a fused U wave. The QT interval is a useful parameter for quantifying the ECG morphology. However, reliable measurement of QT is not straightforward, particularly for hypoglycaemic ECG morphology. The objective of this study was to compare the ability of two methods of QT measurement to distinguish between ECGs recorded during euglycaemia and hypoglycaemia. The first method involves manually setting the intersection of the isoelectric line and the T wave or, where this is not possible, the nadir between the T and U wave. The second method is semi-automatic and fits a tangent to the point of maximum gradient on the downward slope of the T wave. Two independent observers used both methods to measure the QT for high resolution ECG data recorded during a study of 17 non-diabetic subjects undergoing controlled euglycaemia and hypoglycaemia. Using the mean results of the two observers, the mean +/- SD increase in heart rate corrected QT, QTc, for ECGs recorded during euglycaemia and hypoglycaemia was 32 +/- 25 ms for the non-tangent method and 60 +/- 24 ms for the tangent method. Therefore, the tangent method provides greater distinction between ECGs recorded during euglycaemia and hypoglycaemia than the non-tangent method. A potential clinical application could be the non-invasive detection of impending hypoglycaemia at night, which would be of significant benefit to adults and young children with diabetes.
在低血糖期间，典型的体表心电图变化特征为T波平坦且延长，常伴有融合的U波。QT间期是量化心电图形态的一个有用参数。然而，可靠测量QT并非易事，尤其是对于低血糖时的心电图形态。本研究的目的是比较两种QT测量方法区分正常血糖和低血糖期间记录的心电图的能力。第一种方法是手动设定等电位线与T波的交点，若无法做到，则设定T波与U波之间的最低点。第二种方法是半自动的，在T波下降斜率的最大梯度点拟合一条切线。两名独立观察者使用这两种方法测量了17名非糖尿病受试者在进行正常血糖和低血糖对照研究期间记录的高分辨率心电图数据的QT。使用两名观察者的平均结果，正常血糖和低血糖期间记录的心电图的心率校正QT（QTc）的平均±标准差增加，非切线法为32±25毫秒，切线法为60±24毫秒。因此，与非切线法相比，切线法在区分正常血糖和低血糖期间记录的心电图方面提供了更大的差异。一个潜在的临床应用可能是夜间即将发生低血糖的无创检测，这将对糖尿病成人和儿童有显著益处。
