Andršová Irena, Hnatkova Katerina, Šišáková Martina, Toman Ondřej, Smetana Peter, Huster Katharina M, Barthel Petra, Novotný Tomáš, Schmidt Georg, Malik Marek
Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia.
National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Front Physiol. 2020 Dec 15;11:595815. doi: 10.3389/fphys.2020.595815. eCollection 2020.
The electrocardiographic (ECG) assessment of the T peak-T end (Tpe) intervals has been used in many clinical studies, but several related physiological aspects have not been reported. Specifically, the sources of the Tpe differences between different ECG leads have not been systematically researched, the relationship of Tpe duration to underlying heart rate has not been firmly established, and little is known about the mutual correspondence of Tpe intervals measured in different ECG leads. This study evaluated 796,620 10-s 12-lead ECGs obtained from long-term Holters recorded in 639 healthy subjects (311 female) aged 33.8 ± 9.4 years. For each ECG, transformation to orthogonal XYZ lead was used to measure Tpe in the orthogonal vector magnitude (used as a reference for lead-to-lead comparisons) and to construct a three-dimensional T wave loop. The loop roundness was expressed by a ratio between its circumference and length. These ratios were significantly related to the standard deviation of Tpe durations in different ECG leads. At the underlying heart rate of 60 beats per minute, Tpe intervals were shorter in female than in male individuals (82.5 ± 5.6 vs 90.0 ± 6.5 ms, < 0.0001). When studying linear slopes between Tpe intervals measured in different leads and the underlying heart rate, we found only minimal heart rate dependency, which was not systematic across the ECG leads and/or across the population. For any ECG lead, positive Tpe/RR slope was found in some subjects (e.g., 79 and 25% of subjects for V2 and V4 measurements, respectively) and a negative Tpe/RR slope in other subjects (e.g., 40 and 65% for V6 and V5, respectively). The steepest positive and negative Tpe/RR slopes were found for measurements in lead V2 and V4, respectively. In all leads, the Tpe/RR slope values were close to zero, indicating, on average, Tpe changes well below 2 ms for RR interval changes of 100 ms. On average, longest Tpe intervals were measured in lead V2, the shortest in lead III. The study concludes that the Tpe intervals measured in different leads cannot be combined. Irrespective of the measured ECG lead, the Tpe interval is not systematically heart rate dependent, and no heart rate correction should be used in clinical Tpe investigations.
T峰-T末（Tpe）间期的心电图（ECG）评估已在许多临床研究中使用，但一些相关的生理方面尚未见报道。具体而言，不同ECG导联间Tpe差异的来源尚未得到系统研究，Tpe持续时间与基础心率的关系尚未完全确立，不同ECG导联测量的Tpe间期的相互对应关系也知之甚少。本研究评估了从639名年龄为33.8±9.4岁的健康受试者（311名女性）的长期动态心电图记录中获得的796,620份10秒12导联ECG。对于每份ECG，采用转换为正交XYZ导联的方法，在正交向量幅度中测量Tpe（用作导联间比较的参考）并构建三维T波环。环的圆度用其周长与长度的比值表示。这些比值与不同ECG导联中Tpe持续时间的标准差显著相关。在基础心率为每分钟60次时，女性的Tpe间期短于男性（82.5±5.6对90.0±6.5毫秒，<0.0001）。在研究不同导联测量到的Tpe间期与基础心率之间的线性斜率时，我们发现心率依赖性极小，且在ECG导联和/或整个人群中不具有系统性。对于任何ECG导联，在一些受试者中发现了正的Tpe/RR斜率（例如，V2和V4测量分别为79%和25%的受试者），而在其他受试者中发现了负的Tpe/RR斜率（例如，V6和V5分别为40%和65%）。V2和V4导联测量分别发现了最陡的正和负Tpe/RR斜率。在所有导联中，Tpe/RR斜率值均接近零，这表明平均而言，RR间期变化100毫秒时，Tpe变化远低于2毫秒。平均而言，V2导联测量到的Tpe间期最长，III导联最短。该研究得出结论，不同导联测量到的Tpe间期不能合并。无论测量的ECG导联如何，Tpe间期均无系统性心率依赖性，在临床Tpe研究中不应进行心率校正。
