Kenttä Tuomas, Karsikas Mari, Kiviniemi Antti, Tulppo Mikko, Seppänen Tapio, Huikuri Heikki V
Institute of Clinical Medicine, University of Oulu, Finland.
Ann Noninvasive Electrocardiol. 2010 Jul;15(3):264-75. doi: 10.1111/j.1542-474X.2010.00374.x.
QRS/T angle and the cosine of the angle between QRS and T-wave vectors (TCRT), measured from standard 12-lead electrocardiogram (ECG), have been used in risk stratification of patients. This study assessed the possible rate dependence of these variables during exercise ECG in healthy subjects.
Forty healthy volunteers, 20 men and 20 women, aged 34.6 +/- 3.4, underwent an exercise ECG testing. Twelve-lead ECG was recorded from each test subject and the spatial QRS/T angle and TCRT were automatically analyzed in a beat-to-beat manner with custom-made software. The individual TCRT/RR and QRST/RR patterns were fitted with seven different regression models, including a linear model and six nonlinear models.
TCRT and QRS/T angle showed a significant rate dependence, with decreased values at higher heart rates (HR). In individual subjects, the second-degree polynomic model was the best regression model for TCRT/RR and QRST/RR slopes. It provided the best fit for both exercise and recovery. The overall TCRT/RR and QRST/RR slopes were similar between men and women during exercise and recovery. However, women had predominantly higher TCRT and QRS/T values. With respect to time, the dynamics of TCRT differed significantly between men and women; with a steeper exercise slope in women (women, -0.04/min vs -0.02/min in men, P < 0.0001). In addition, evident hysteresis was observed in the TCRT/RR slopes; with higher TCRT values during exercise.
The individual patterns of TCRT and QRS/T angle are affected by HR and gender. Delayed rate adaptation creates hysteresis in the TCRT/RR slopes.
从标准12导联心电图（ECG）测量的QRS/T角以及QRS与T波向量之间夹角的余弦值（TCRT）已用于患者的风险分层。本研究评估了健康受试者运动心电图期间这些变量可能存在的心率依赖性。
40名健康志愿者，20名男性和20名女性，年龄34.6±3.4岁，接受运动心电图测试。记录每个受试者的12导联心电图，并使用定制软件逐搏自动分析空间QRS/T角和TCRT。将个体TCRT/RR和QRST/RR模式与七种不同的回归模型进行拟合，包括线性模型和六种非线性模型。
TCRT和QRS/T角显示出显著的心率依赖性，心率（HR）较高时数值降低。在个体受试者中，二次多项式模型是TCRT/RR和QRST/RR斜率的最佳回归模型。它在运动和恢复过程中均提供了最佳拟合。运动和恢复期间，男性和女性的总体TCRT/RR和QRST/RR斜率相似。然而，女性的TCRT和QRS/T值主要较高。在时间方面，男性和女性的TCRT动态存在显著差异；女性的运动斜率更陡（女性为-0.04/分钟，男性为-0.02/分钟，P<0.0001）。此外，在TCRT/RR斜率中观察到明显的滞后现象；运动期间TCRT值较高。
TCRT和QRS/T角的个体模式受心率和性别的影响。速率适应延迟在TCRT/RR斜率中产生滞后现象。
