Antepartum non-invasive evaluation of opening and closing timings of the cardiac valves in fetal cardiac cycle.

In this study, we propose a non-invasive algorithm to recognize the timings of fetal cardiac events on the basis of analysis of fetal ECG (FECG) and Doppler ultrasound signals. Multiresolution wavelet analysis enabled the frequency contents of the Doppler signals to be linked to the opening (o) and closing (c) of the heart's valves (Aortic (A) and Mitral (M)). M-mode, B-mode and pulsed Doppler ultrasound were used to verify the timings of opening and closure of these valves. In normal fetuses, the time intervals from Q-wave of QRS complex of FECG to opening and closing of aortic valve, i.e., Q-Ao and Q-Ac were found to be 79.3 +/- 17.4 and 224.7 +/- 13.3 ms, respectively. For the mitral valve, Q-Mc and Q-Mo were found to be 27.7 +/- 9.4 and 294.6 +/- 21.3 ms, respectively. Correlations among the timings in opening and closing of cardiac valves were found to be higher in abnormal fetuses than that in normal ones.