A baseline tracking algorithm for drift reduction in electrocardiography

Baseline drift reduction in electrocardiogram (ECG) by a high-pass digital/analog filter at frequencies higher than 0.5 Hz distort the waveshapes of the ECG signal. The authors describe a drift-reduction method, called the baseline tracking algorithm (BTA), that preserves the ECG waveshapes. The isoelectric regions before the P-wave and after the T-wave and the P-Q interval of an ECG signal are used for drift reduction. The BTA makes drift correction on a beat-by-beat basis. The algorithm was tested on various drift/ECG amplitude (1.43 to 0.005) and frequency (3.3 to 0.006) ratios, and for stress test ECG. Test results show that, at low frequency, the BTA can correct for drift in the ECG signal when the drift/ECG amplitude ratio is less than 0.6. At low drift amplitude, the BTA can correct for drift when the drift/ECG frequency ratio is less than 0.67. The stress-test ECG drift correction was very satisfactory.<>