Department of Electrical Engineering, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-010 Belo Horizonte, MG, Brazil.
Physiol Meas. 2010 Jan;31(1):45-58. doi: 10.1088/0967-3334/31/1/004. Epub 2009 Nov 26.
Power-line interference is always present in indoor biopotential measurements, even when its extremely low magnitude makes it imperceptible. In special situations, this kind of interference can be neglected, but this is not a general rule. In laboratory experiments and clinical analysis, it is hard (and expensive) to isolate the subject of measurement from electrical fields produced by a power line. In human biopotential recordings, it is common practice to apply a 50/60 Hz notch filter to reduce this kind of interference. In such cases, there is no considerable distortion observed on the recorded signal. However, experiments showed that it is not true for rat ECG recordings. Several kinds of notch filters (analog and digital) were implemented for evaluation of the distortion caused on ECG signals. These filters were applied to ECGs of humans and rats and then distortion estimates were computed from their resulting signals. The comparison of these estimates showed that, as experimentally observed, rat ECG signals are significantly distorted and deformed when a 50/60 Hz notch filter is applied to them, while human ECGs are not. The major goal of this paper is to show that the use of a notch filter for power-line interference rejection, when applied to rat ECG recordings, can severely deform the QRS complex of such signals, warning researchers against its non-deliberate usage.
电力线干扰在室内生物电势测量中始终存在，即使其极低的幅度使其无法察觉。在特殊情况下，这种干扰可以忽略不计，但这并不是普遍规律。在实验室实验和临床分析中，很难（且昂贵）将测量对象与电源线产生的电场隔离开来。在人体生物电势记录中，通常采用 50/60 Hz 陷波滤波器来减少这种干扰。在这种情况下，记录信号上没有观察到明显的失真。然而，实验表明，大鼠心电图记录并非如此。为了评估对 ECG 信号造成的失真，实现了几种类型的陷波滤波器（模拟和数字）。将这些滤波器应用于人类和大鼠的 ECG，并从它们的结果信号中计算失真估计值。这些估计值的比较表明，正如实验观察到的那样，当对大鼠 ECG 应用 50/60 Hz 陷波滤波器时，大鼠 ECG 信号会严重失真和变形，而人类 ECG 则不会。本文的主要目的是表明，当应用于大鼠 ECG 记录时，陷波滤波器用于抑制电力线干扰可能会严重扭曲这些信号的 QRS 复合体，警告研究人员不要故意使用它。
