Shaw G R, Savard P
Research Center, Sacré-Coeur Hospital, Montréal, Québec, Canada.
IEEE Trans Biomed Eng. 1995 Jul;42(7):736-41. doi: 10.1109/10.391174.
Detection of subtle beat-to-beat variations in the morphology of the ECG is complicated by the effects of alignment errors and respiration. A method of directly estimating the alignment error (trigger jitter) from an ECG is derived by relating the variance to the squared slope of the averaged QRS complex. Results based on recordings obtained from 12 normal subjects and alignment performed by the cross-correlation method showed that the alignment errors were dependent upon the choice of the alignment channel, with the best distribution of the errors occurring when alignment was based on the vector magnitude of the three orthogonal leads. The estimated average alignment errors ranged from 0.33-0.42 ms, which were near the optimal value of 0.29 ms based on the sampling rate of 1000 samples/s. It was shown that the effects of respiration could be reduced by normalizing the amplitude of the QRS complexes. It was also estimated that a significant proportion of the variation (0.54-0.67) in the normalized ECG's could be attributed to alignment errors and noise.
心电图形态中细微的逐搏变化检测会因对齐误差和呼吸的影响而变得复杂。通过将方差与平均QRS波群的平方斜率相关联，得出了一种直接从心电图估计对齐误差（触发抖动）的方法。基于从12名正常受试者获得的记录以及通过互相关方法进行对齐的结果表明，对齐误差取决于对齐通道的选择，当基于三个正交导联的矢量幅度进行对齐时，误差分布最佳。估计的平均对齐误差范围为0.33 - 0.42毫秒，基于1000样本/秒的采样率，该误差接近最佳值0.29毫秒。结果表明，通过对QRS波群的幅度进行归一化，可以减少呼吸的影响。据估计，归一化心电图中很大一部分变化（0.54 - 0.67）可归因于对齐误差和噪声。
