A Correction Formula for the ST Segment Measurements for the AC-coupled Electrocardiograms

TY - JOUR

T1 - A Correction Formula for the ST Segment Measurements for the AC-coupled Electrocardiograms

AU - Schmid, Ramun

AU - Isaksen, Jonas

AU - Leber, Remo

AU - Schmid, Hans-Jakob

AU - Generali, Gianluca

AU - Abacherli, Roger

PY - 2017/8

Y1 - 2017/8

N2 - Goal: The ST segment of an electrocardiogram (ECG) is very important for the correct diagnosis of an acute myocardial infarction. Most clinical ECGs are recorded using an ACcoupled ECG amplifier. It is well known, that firstorder high-pass filters used for the AC coupling can affect the ST segment of an ECG. This effect is stronger the higher the filter's cut-off frequency is and the larger the QRS integral is. We present a formula that estimates these changes in the ST segment and therefore allows for correcting ST measurements that are based on an ACcoupled ECG. Methods: The presented correction formula can be applied when only four parameters are known: the possibly estimated QRS area A, the QRS duration W, the beat-to-beat interval TRR, and the filter time constant T, further, the time point Tj to correct-after the J point-must be specified. Results: The formula is correct within 0.6% until 40ms after the J point and within 6% until 80 ms after the J point. Conclusion and significance: It is not necessary to have the raw data available and the formula therefore opens up the possibility of reevaluating studies that are based on ACcoupled ECGs and compare the results of such studies with studies that are based on newer, DC-coupled ECGs.

AB - Goal: The ST segment of an electrocardiogram (ECG) is very important for the correct diagnosis of an acute myocardial infarction. Most clinical ECGs are recorded using an ACcoupled ECG amplifier. It is well known, that firstorder high-pass filters used for the AC coupling can affect the ST segment of an ECG. This effect is stronger the higher the filter's cut-off frequency is and the larger the QRS integral is. We present a formula that estimates these changes in the ST segment and therefore allows for correcting ST measurements that are based on an ACcoupled ECG. Methods: The presented correction formula can be applied when only four parameters are known: the possibly estimated QRS area A, the QRS duration W, the beat-to-beat interval TRR, and the filter time constant T, further, the time point Tj to correct-after the J point-must be specified. Results: The formula is correct within 0.6% until 40ms after the J point and within 6% until 80 ms after the J point. Conclusion and significance: It is not necessary to have the raw data available and the formula therefore opens up the possibility of reevaluating studies that are based on ACcoupled ECGs and compare the results of such studies with studies that are based on newer, DC-coupled ECGs.

U2 - 10.1109/TBME.2016.2624746

DO - 10.1109/TBME.2016.2624746

M3 - Journal article

C2 - 27834635

SN - 0018-9294

VL - 64

SP - 1834

EP - 1840

JO - IEEE Transactions on Biomedical Engineering

JF - IEEE Transactions on Biomedical Engineering

IS - 8

ER -