Antepartum Noninvasive Evaluation of Fetal Myocardial Performance from Continuous Doppler Signals and Its Research Potential

In this chapter, we summarized various noninvasive techniques to estimate the timings of fetal cardiac events based on analysis of fetal ECG (FECG) and Doppler ultrasound signals (DUS). Fetal myocardial performance indices are applied to assess systolic and diastolic function aspects in developing fetal heart, and cardiac timing events can also be evaluated. Firstly, we explained a method based on empirical mode decomposition (EMD) and the kurtosis statistics to estimate beat-by-beat fetal heart rate and its variability from DUS. Secondly, a hybrid model using multiresolution wavelet analysis enabled the frequency contents of the DUS 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 images were used to verify the timings of the opening and closing of these valves. The systolic and diastolic intervals include the isovolumic contraction time (ICT), isovolumic relaxation time (IRT), ventricular ejection time (VET), and ventricular filling time (VFT). TI and KI were calculated using the formula (ICT + IRT)/VET and (ICT + IRT)/VFT, respectively. Finally, we showcased several examples of how fetal myocardial performance indices were applied to assess systolic and diastolic function in developing fetal hearts. The published results showed normal values of Tei index (TI) and modified TI (KI) for systolic and diastolic performance in early (<30 weeks), mid (30–35 weeks), and late (36–41 weeks) relating to both normal fetuses and fetuses carrying a variety of fetal abnormalities, which do not call for precise anatomic imaging.