Frankel R A, Pottala E W, Bowser R W, Bailey J J
Department of Physiology and Biophysics, Medical College of Ohio, Toledo.
J Electrocardiol. 1991 Oct;24(4):315-23. doi: 10.1016/0022-0736(91)90014-d.
Accurate monitoring of the ST-segment displacements in real-time environments can be distorted by the nonlinear phase response of a baseline filter such as the single-pole, high-pass (0.5 Hz) filter that is standard in the industry today. The authors have previously constructed a four-pole null phase (1.0 Hz) filter that is nearly ideal in suppressing baseline wander while preserving ST-segment accuracy; however, this foreward/backward filter requires capture of a large ECG segment before filtering, thereby producing a delay that is unacceptable in a real-time environment. As a practical compromise, a two-pole, phase-compensated (1.0 Hz) filter was constructed while introducing a small time delay (160 ms). It performs much better than the "standard filter" and almost as well as the "ideal" filter in several tests, namely (1) suppression of baseline wander in a series of ECGs, (2) suppression of artificial baseline, (3) response to a triangular impulse wave (American Heart Association test), and (4) J-point displacement in several ECGs.
在实时环境中，对ST段位移的精确监测可能会因基线滤波器（如当今行业标准的单极高通（0.5 Hz）滤波器）的非线性相位响应而失真。作者先前构建了一种四极零相位（1.0 Hz）滤波器，该滤波器在抑制基线漂移同时保持ST段准确性方面几乎是理想的；然而，这种前向/后向滤波器在滤波前需要捕获较大的心电图段，从而产生在实时环境中不可接受的延迟。作为一种实际的折衷方案，构建了一种双极相位补偿（1.0 Hz）滤波器，同时引入了较小的时间延迟（160毫秒）。在多项测试中，它的性能比“标准滤波器”好得多，几乎与“理想”滤波器一样好，即（1）抑制一系列心电图中的基线漂移，（2）抑制人工基线，（3）对三角脉冲波的响应（美国心脏协会测试），以及（4）多个心电图中的J点位移。
