Abstract：
Objective. Beat-to-beat fluctuations in the QT interval-QT variability (QTV)-have been shown to vary amongst the different ECG leads. This study aims to compare the utility of single and multi-lead ECG to disentangle the mechanisms contributing to QTV.Approach. Twelve-lead ECG was analysed in 57 coronary artery disease patients before and after an elective percutaneous transluminal coronary angiography (PTCA) procedure. QT, RR and respiration time series were extracted. QTV was decomposed into contributions by heart rate, respiration and QTV independent of heart rate and respiration using parametric autoregressive modelling. Signal-to-noise ratio, model goodness-of-fit, mean QT, corrected QT, QT variability and RR variability were also computed. Results from two single leads (Lead II and V5) and three one-dimensional representations of 12-lead ECG (principal component analysis (PCA), vector magnitude (VM), and root mean square of the 8 independent leads of the standard 12 leads (RMS8)) were compared during resting conditions, before and after PTCA, and between patients with myocardial infarction and those without.Main results. At baseline, mean QT and corrected QT were significantly lower in VM and RMS8 compared to single leads. While overall QT variability was not different between the leads, QT independent of heart rate and respiration was significantly lower in VM and RMS8. Following PTCA, changes in these variables were similar in all leads. Differences between patients with MI and those without MI were consistent in all leads.Significance. Despite the differences in some QTV components amongst various leads, single-lead ECG could be sufficient for analyzing QTV in populations with pathological cardiovascular conditions compared to those without, or for quantification of intervention effects.
摘要：
Objective.QT间期-QT变异性（QTV）的心跳波动已显示在不同的ECG导联中有所不同。这项研究旨在比较单导联和多导联心电图的实用性，以解开导致QTV的机制。方法。在选择性经皮冠状动脉造影（PTCA）手术前后，对57例冠状动脉疾病患者进行了十二导联心电图分析。QT,提取RR和呼吸时间序列。QTV被分解为心率的贡献，使用参数自回归建模，呼吸和QTV与心率和呼吸无关。信噪比,模型拟合优度，平均QT，校正后的QT,还计算了QT变异性和RR变异性。来自两个单导联（导联II和V5）和三个12导联ECG的一维表示的结果（主成分分析（PCA），矢量幅度(VM)，在静息条件下比较了标准12导联（RMS8）的8个独立导联的均方根，PTCA前后,以及心肌梗塞患者和没有心肌梗塞的患者之间。主要结果。在基线,与单导联相比,VM和RMS8的平均QT和校正QT显著更低.虽然导联之间的整体QT变异性没有差异，与心率和呼吸无关的QT在VM和RMS8中明显较低。在PTCA之后,所有导联中这些变量的变化相似。在所有导联中，MI患者和无MI患者之间的差异是一致的。意义。尽管QTV组件在不同的线索之间存在差异，与没有病理性心血管疾病的人群相比，单导联ECG足以分析QTV，或量化干预效果。
