Avitia Roberto L, Reyna Marco A, Bravo-Zanoguera Miguel E, Cetto Lucio A
University Autonomous of Baja California, Benito Juarez Blvd. s/n. Mexicali B.C., 21280 Mexico.
Biomed Tech (Berl). 2013 Apr;58(2):179-86. doi: 10.1515/bmt-2012-0120.
Ventricular late potentials (VLPs) are small-amplitude waves with a short duration that appear at the end part of the QRS complex, making a QRS complex duration larger. The signal-averaged electrocardiography (ECG) technique enhances VLPs and beats, assuming noise as the only random variable. However, ECG signals are not completely stationary and different elongations appear in both time and amplitude in each beat. This research proposes to use piecewise linear approximation to segment each beat and performs the alignment of the beats using the technique known as derivative dynamic time-warping to have beats better aligned and consequently enhance the presence of VLPs. We recorded high-resolution ECGs (HRECGs) from 50 subjects in supine position with no heart-stroke antecedents. VLPs were created synthetically and added to the HRECGs. Two cases were evaluated: (i) duration of the QRS complexes with VLPs without beats alignment, and (ii) duration of QRS complexes with VLPs using beats alignment in time and amplitude. Considering QRS duration as an indicative of VLP presence, results show that when using beats alignment in time and amplitude it is possible to reach a sensitivity of 0.96 and a specificity of 0.52, as opposed to 0.72 and 0.40, respectively, when using only averaging without beats alignment in time and amplitude.
心室晚电位（VLPs）是出现在QRS波群末端的小振幅、短持续时间的波，会使QRS波群持续时间延长。信号平均心电图（ECG）技术可增强心室晚电位和心搏，将噪声视为唯一的随机变量。然而，心电图信号并非完全静止，每个心搏在时间和幅度上都会出现不同程度的变化。本研究建议使用分段线性近似对每个心搏进行分割，并使用称为导数动态时间规整的技术对心搏进行对齐，以使心搏更好地对齐，从而增强心室晚电位的显现。我们记录了50名无中风病史的受试者仰卧位时的高分辨率心电图（HRECGs）。合成心室晚电位并将其添加到高分辨率心电图中。评估了两种情况：（i）未进行心搏对齐时带有心室晚电位的QRS波群持续时间，以及（ii）在时间和幅度上进行心搏对齐时带有心室晚电位的QRS波群持续时间。将QRS持续时间作为心室晚电位存在的指标，结果表明，在时间和幅度上进行心搏对齐时，灵敏度可达0.96，特异性可达0.52，而仅进行平均且未在时间和幅度上进行心搏对齐时，灵敏度和特异性分别为0.72和0.40。
