Assessment of Coupling between Trans-Abdominally Acquired Fetal ECG and Uterine Activity by Bivariate Phase-Rectified Signal Averaging Analysis
Figure 1
Description of the Bivariate Phase Rectified Signal Averaging (BPRSA) method.
Panel a) Uterine Activity by EHG (trigger signal): each data point is the average of raw signal every 2 seconds. Each black dot represents an anchor point (EHG increases). Panel b) fetal heart rate by ECG (target signal). The empty circles represent anchor points derived from the EHG signal. Panel c) Segments of fetal heart rate to average, centered around the anchor point (time windows of 200 seconds, each data point(i) is the average of fHR every 2 seconds). Panel d) phase rectification at the anchor points and signal averaging. Panel e) BPRSA graph representing PRSA transformation of Uterine Activity (grey line) and BPRSA transformation of fetal heart rate (bold line).